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<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code> --- Interfaces to Unix &quot;databases&quot;</a><ul>
<li><a class="reference internal" href="#module-dbm.sqlite3"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.sqlite3</span></code> --- SQLite backend for dbm</a></li>
<li><a class="reference internal" href="#module-dbm.gnu"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code> --- GNU database manager</a></li>
<li><a class="reference internal" href="#module-dbm.ndbm"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code> --- New Database Manager</a></li>
<li><a class="reference internal" href="#module-dbm.dumb"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code> --- Portable DBM implementation</a></li>
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  <section id="module-dbm">
<span id="dbm-interfaces-to-unix-databases"></span><h1><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code> --- Interfaces to Unix &quot;databases&quot;<a class="headerlink" href="#module-dbm" title="Link to this heading">¶</a></h1>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/dbm/__init__.py">Lib/dbm/__init__.py</a></p>
<hr class="docutils" />
<p><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code> is a generic interface to variants of the DBM database:</p>
<ul class="simple">
<li><p><a class="reference internal" href="#module-dbm.sqlite3" title="dbm.sqlite3: SQLite backend for dbm"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.sqlite3</span></code></a></p></li>
<li><p><a class="reference internal" href="#module-dbm.gnu" title="dbm.gnu: GNU database manager"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code></a></p></li>
<li><p><a class="reference internal" href="#module-dbm.ndbm" title="dbm.ndbm: The New Database Manager"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code></a></p></li>
<p>If none of these modules are installed, the
slow-but-simple implementation in module <a class="reference internal" href="#module-dbm.dumb" title="dbm.dumb: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code></a> will be used.  There
is a <a class="reference external" href="https://www.jcea.es/programacion/pybsddb.htm">third party interface</a> to
the Oracle Berkeley DB.</p>
<dl class="py exception">
<dt class="sig sig-object py" id="dbm.error">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">dbm.</span></span><span class="sig-name descname"><span class="pre">error</span></span><a class="headerlink" href="#dbm.error" title="Link to this definition">¶</a></dt>
<dd><p>A tuple containing the exceptions that can be raised by each of the supported
modules, with a unique exception also named <a class="reference internal" href="#dbm.error" title="dbm.error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">dbm.error</span></code></a> as the first
item --- the latter is used when <code class="xref py py-exc docutils literal notranslate"><span class="pre">dbm.error</span></code> is raised.</p>
<dl class="py function">
<dt class="sig sig-object py" id="dbm.whichdb">
<span class="sig-prename descclassname"><span class="pre">dbm.</span></span><span class="sig-name descname"><span class="pre">whichdb</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">filename</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#dbm.whichdb" title="Link to this definition">¶</a></dt>
<dd><p>This function attempts to guess which of the several simple database modules
available --- <a class="reference internal" href="#module-dbm.sqlite3" title="dbm.sqlite3: SQLite backend for dbm"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.sqlite3</span></code></a>, <a class="reference internal" href="#module-dbm.gnu" title="dbm.gnu: GNU database manager"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code></a>, <a class="reference internal" href="#module-dbm.ndbm" title="dbm.ndbm: The New Database Manager"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code></a>,
or <a class="reference internal" href="#module-dbm.dumb" title="dbm.dumb: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code></a> --- should be used to open a given file.</p>
<p>Return one of the following values:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">None</span></code> if the file can't be opened because it's unreadable or doesn't exist</p></li>
<li><p>the empty string (<code class="docutils literal notranslate"><span class="pre">''</span></code>) if the file's format can't be guessed</p></li>
<li><p>a string containing the required module name, such as <code class="docutils literal notranslate"><span class="pre">'dbm.ndbm'</span></code> or <code class="docutils literal notranslate"><span class="pre">'dbm.gnu'</span></code></p></li>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.11: </span><em>filename</em> accepts a <a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>.</p>
<dl class="py function">
<dt class="sig sig-object py" id="dbm.open">
<span class="sig-prename descclassname"><span class="pre">dbm.</span></span><span class="sig-name descname"><span class="pre">open</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">file</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flag</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">'r'</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">mode</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0o666</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#dbm.open" title="Link to this definition">¶</a></dt>
<dd><p>Open a database and return the corresponding database object.</p>
<dl class="field-list simple">
<dt class="field-odd">پارامترها<span class="colon">:</span></dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>file</strong> (<a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>) -- <p>The database file to open.</p>
<p>If the database file already exists, the <a class="reference internal" href="#dbm.whichdb" title="dbm.whichdb"><code class="xref py py-func docutils literal notranslate"><span class="pre">whichdb()</span></code></a> function is used to
determine its type and the appropriate module is used; if it does not exist,
the first submodule listed above that can be imported is used.</p>
<li><p><strong>flag</strong> (<a class="reference internal" href="stdtypes.html#str" title="str"><em>str</em></a>) -- <ul>
<li><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code> (default): Open existing database for reading only.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'w'</span></code>: Open existing database for reading and writing.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code>: Open database for reading and writing, creating it if it doesn't exist.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'n'</span></code>: Always create a new, empty database, open for reading and writing.</p></li>
<li><p><strong>mode</strong> (<a class="reference internal" href="functions.html#int" title="int"><em>int</em></a>) -- The Unix file access mode of the file (default: octal <code class="docutils literal notranslate"><span class="pre">0o666</span></code>),
used only when the database has to be created.</p></li>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.11: </span><em>file</em> accepts a <a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>.</p>
<p>The object returned by <a class="reference internal" href="#dbm.open" title="dbm.open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> supports the basic
functionality of mutable <a class="reference internal" href="../glossary.html#term-mapping"><span class="xref std std-term">mappings</span></a>;
keys and their corresponding values can be stored, retrieved, and
deleted, and iteration, the <a class="reference internal" href="../reference/expressions.html#in"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">in</span></code></a> operator and methods <code class="xref py py-meth docutils literal notranslate"><span class="pre">keys()</span></code>,
<code class="xref py py-meth docutils literal notranslate"><span class="pre">get()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">clear()</span></code> are available.
The <code class="xref py py-meth docutils literal notranslate"><span class="pre">keys()</span></code> method returns a list instead of a view object.
The <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> method requires two arguments.</p>
<p>Key and values are always stored as <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>. This means that when
strings are used they are implicitly converted to the default encoding before
being stored.</p>
<p>These objects also support being used in a <a class="reference internal" href="../reference/compound_stmts.html#with"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code></a> statement, which
will automatically close them when done.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.2: </span><code class="xref py py-meth docutils literal notranslate"><span class="pre">get()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> methods are now available for all
<code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code> backends.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.4: </span>Added native support for the context management protocol to the objects
returned by <a class="reference internal" href="#dbm.open" title="dbm.open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.8: </span>Deleting a key from a read-only database raises a database module specific exception
instead of <a class="reference internal" href="exceptions.html#KeyError" title="KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.13: </span><code class="xref py py-meth docutils literal notranslate"><span class="pre">clear()</span></code> methods are now available for all <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code> backends.</p>
<p>The following example records some hostnames and a corresponding title,  and
then prints out the contents of the database:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">dbm</span>
<span class="c1"># Open database, creating it if necessary.</span>
<span class="k">with</span> <span class="n">dbm</span><span class="o">.</span><span class="n">open</span><span class="p">(</span><span class="s1">'cache'</span><span class="p">,</span> <span class="s1">'c'</span><span class="p">)</span> <span class="k">as</span> <span class="n">db</span><span class="p">:</span>
    <span class="c1"># Record some values</span>
    <span class="n">db</span><span class="p">[</span><span class="sa">b</span><span class="s1">'hello'</span><span class="p">]</span> <span class="o">=</span> <span class="sa">b</span><span class="s1">'there'</span>
    <span class="n">db</span><span class="p">[</span><span class="s1">'www.python.org'</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'Python Website'</span>
    <span class="n">db</span><span class="p">[</span><span class="s1">'www.cnn.com'</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'Cable News Network'</span>
    <span class="c1"># Note that the keys are considered bytes now.</span>
    <span class="k">assert</span> <span class="n">db</span><span class="p">[</span><span class="sa">b</span><span class="s1">'www.python.org'</span><span class="p">]</span> <span class="o">==</span> <span class="sa">b</span><span class="s1">'Python Website'</span>
    <span class="c1"># Notice how the value is now in bytes.</span>
    <span class="k">assert</span> <span class="n">db</span><span class="p">[</span><span class="s1">'www.cnn.com'</span><span class="p">]</span> <span class="o">==</span> <span class="sa">b</span><span class="s1">'Cable News Network'</span>
    <span class="c1"># Often-used methods of the dict interface work too.</span>
    <span class="nb">print</span><span class="p">(</span><span class="n">db</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s1">'python.org'</span><span class="p">,</span> <span class="sa">b</span><span class="s1">'not present'</span><span class="p">))</span>
    <span class="c1"># Storing a non-string key or value will raise an exception (most</span>
    <span class="c1"># likely a TypeError).</span>
    <span class="n">db</span><span class="p">[</span><span class="s1">'www.yahoo.com'</span><span class="p">]</span> <span class="o">=</span> <span class="mi">4</span>
<span class="c1"># db is automatically closed when leaving the with statement.</span>
</pre></div>
<div class="admonition seealso">
<p class="admonition-title">همچنین ملاحظه نمائید</p>
<dl class="simple">
<dt>Module <a class="reference internal" href="shelve.html#module-shelve" title="shelve: Python object persistence."><code class="xref py py-mod docutils literal notranslate"><span class="pre">shelve</span></code></a></dt><dd><p>Persistence module which stores non-string data.</p>
<p>The individual submodules are described in the following sections.</p>
<section id="module-dbm.sqlite3">
<span id="dbm-sqlite3-sqlite-backend-for-dbm"></span><h2><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.sqlite3</span></code> --- SQLite backend for dbm<a class="headerlink" href="#module-dbm.sqlite3" title="Link to this heading">¶</a></h2>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.13.</span></p>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/dbm/sqlite3.py">Lib/dbm/sqlite3.py</a></p>
<hr class="docutils" />
<p>This module uses the standard library <a class="reference internal" href="sqlite3.html#module-sqlite3" title="sqlite3: A DB-API 2.0 implementation using SQLite 3.x."><code class="xref py py-mod docutils literal notranslate"><span class="pre">sqlite3</span></code></a> module to provide an
SQLite backend for the <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code> module.
The files created by <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.sqlite3</span></code> can thus be opened by <code class="xref py py-mod docutils literal notranslate"><span class="pre">sqlite3</span></code>,
or any other SQLite browser, including the SQLite CLI.</p>
<div class="availability docutils container">
<p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">در دسترس بودن</span></a>: not WASI.</p>
<p>This module does not work or is not available on WebAssembly. See
<a class="reference internal" href="intro.html#wasm-availability"><span class="std std-ref">WebAssembly platforms</span></a> for more information.</p>
<dl class="py function">
<dt class="sig sig-object py" id="dbm.sqlite3.open">
<span class="sig-prename descclassname"><span class="pre">dbm.sqlite3.</span></span><span class="sig-name descname"><span class="pre">open</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">filename</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">flag</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">'r'</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">mode</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0o666</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#dbm.sqlite3.open" title="Link to this definition">¶</a></dt>
<dd><p>Open an SQLite database.</p>
<dl class="field-list simple">
<dt class="field-odd">پارامترها<span class="colon">:</span></dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>filename</strong> (<a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>) -- The path to the database to be opened.</p></li>
<li><p><strong>flag</strong> (<a class="reference internal" href="stdtypes.html#str" title="str"><em>str</em></a>) -- <ul>
<li><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code> (default): Open existing database for reading only.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'w'</span></code>: Open existing database for reading and writing.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code>: Open database for reading and writing, creating it if it doesn't exist.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'n'</span></code>: Always create a new, empty database, open for reading and writing.</p></li>
<li><p><strong>mode</strong> -- The Unix file access mode of the file (default: octal <code class="docutils literal notranslate"><span class="pre">0o666</span></code>),
used only when the database has to be created.</p></li>
<p>The returned database object behaves similar to a mutable <a class="reference internal" href="../glossary.html#term-mapping"><span class="xref std std-term">mapping</span></a>,
but the <code class="xref py py-meth docutils literal notranslate"><span class="pre">keys()</span></code> method returns a list, and
the <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> method requires two arguments.
It also supports a &quot;closing&quot; context manager via the <a class="reference internal" href="../reference/compound_stmts.html#with"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code></a> keyword.</p>
<p>The following method is also provided:</p>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.sqlite3.sqlite3.close">
<span class="sig-prename descclassname"><span class="pre">sqlite3.</span></span><span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dbm.sqlite3.sqlite3.close" title="Link to this definition">¶</a></dt>
<dd><p>Close the SQLite database.</p>
<section id="module-dbm.gnu">
<span id="dbm-gnu-gnu-database-manager"></span><h2><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code> --- GNU database manager<a class="headerlink" href="#module-dbm.gnu" title="Link to this heading">¶</a></h2>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/dbm/gnu.py">Lib/dbm/gnu.py</a></p>
<hr class="docutils" />
<p>The <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code> module provides an interface to the <abbr title="GNU dbm">GDBM</abbr>
library, similar to the <a class="reference internal" href="#module-dbm.ndbm" title="dbm.ndbm: The New Database Manager"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code></a> module, but with additional
functionality like crash tolerance.</p>
<div class="admonition note">
<p class="admonition-title">توجه</p>
<p>The file formats created by <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code> and <a class="reference internal" href="#module-dbm.ndbm" title="dbm.ndbm: The New Database Manager"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code></a> are incompatible
and can not be used interchangeably.</p>
<div class="availability docutils container">
<p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">در دسترس بودن</span></a>: not Android, not iOS, not WASI.</p>
<p>This module is not supported on <a class="reference internal" href="intro.html#mobile-availability"><span class="std std-ref">mobile platforms</span></a>
or <a class="reference internal" href="intro.html#wasm-availability"><span class="std std-ref">WebAssembly platforms</span></a>.</p>
<div class="availability docutils container">
<p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">در دسترس بودن</span></a>: Unix.</p>
<dl class="py exception">
<dt class="sig sig-object py" id="dbm.gnu.error">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">dbm.gnu.</span></span><span class="sig-name descname"><span class="pre">error</span></span><a class="headerlink" href="#dbm.gnu.error" title="Link to this definition">¶</a></dt>
<dd><p>Raised on <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code>-specific errors, such as I/O errors. <a class="reference internal" href="exceptions.html#KeyError" title="KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a> is
raised for general mapping errors like specifying an incorrect key.</p>
<dl class="py data">
<dt class="sig sig-object py" id="dbm.gnu.open_flags">
<span class="sig-prename descclassname"><span class="pre">dbm.gnu.</span></span><span class="sig-name descname"><span class="pre">open_flags</span></span><a class="headerlink" href="#dbm.gnu.open_flags" title="Link to this definition">¶</a></dt>
<dd><p>A string of characters the <em>flag</em> parameter of <a class="reference internal" href="#dbm.gnu.open" title="dbm.gnu.open"><code class="xref py py-meth docutils literal notranslate"><span class="pre">open()</span></code></a> supports.</p>
<dl class="py function">
<dt class="sig sig-object py" id="dbm.gnu.open">
<span class="sig-prename descclassname"><span class="pre">dbm.gnu.</span></span><span class="sig-name descname"><span class="pre">open</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">filename</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flag</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">'r'</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">mode</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0o666</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em><span class="sig-paren">)</span><a class="headerlink" href="#dbm.gnu.open" title="Link to this definition">¶</a></dt>
<dd><p>Open a GDBM database and return a <code class="xref py py-class docutils literal notranslate"><span class="pre">gdbm</span></code> object.</p>
<dl class="field-list simple">
<dt class="field-odd">پارامترها<span class="colon">:</span></dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>filename</strong> (<a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>) -- The database file to open.</p></li>
<li><p><strong>flag</strong> (<a class="reference internal" href="stdtypes.html#str" title="str"><em>str</em></a>) -- <ul>
<li><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code> (default): Open existing database for reading only.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'w'</span></code>: Open existing database for reading and writing.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code>: Open database for reading and writing, creating it if it doesn't exist.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'n'</span></code>: Always create a new, empty database, open for reading and writing.</p></li>
<p>The following additional characters may be appended
to control how the database is opened:</p>
<li><p><code class="docutils literal notranslate"><span class="pre">'f'</span></code>: Open the database in fast mode.
Writes to the database will not be synchronized.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'s'</span></code>: Synchronized mode.
Changes to the database will be written immediately to the file.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'u'</span></code>: Do not lock database.</p></li>
<p>Not all flags are valid for all versions of GDBM.
See the <a class="reference internal" href="#dbm.gnu.open_flags" title="dbm.gnu.open_flags"><code class="xref py py-data docutils literal notranslate"><span class="pre">open_flags</span></code></a> member for a list of supported flag characters.</p>
<li><p><strong>mode</strong> (<a class="reference internal" href="functions.html#int" title="int"><em>int</em></a>) -- The Unix file access mode of the file (default: octal <code class="docutils literal notranslate"><span class="pre">0o666</span></code>),
used only when the database has to be created.</p></li>
<dt class="field-even">برانگیختن<span class="colon">:</span></dt>
<dd class="field-even"><p><a class="reference internal" href="#dbm.gnu.error" title="dbm.gnu.error"><strong>error</strong></a> -- If an invalid <em>flag</em> argument is passed.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.11: </span><em>filename</em> accepts a <a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>.</p>
<p><code class="xref py py-class docutils literal notranslate"><span class="pre">gdbm</span></code> objects behave similar to mutable <a class="reference internal" href="../glossary.html#term-mapping"><span class="xref std std-term">mappings</span></a>,
but methods <code class="xref py py-meth docutils literal notranslate"><span class="pre">items()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">values()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">pop()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">popitem()</span></code>,
and <code class="xref py py-meth docutils literal notranslate"><span class="pre">update()</span></code> are not supported,
the <code class="xref py py-meth docutils literal notranslate"><span class="pre">keys()</span></code> method returns a list, and
the <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> method requires two arguments.
It also supports a &quot;closing&quot; context manager via the <a class="reference internal" href="../reference/compound_stmts.html#with"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code></a> keyword.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.2: </span>Added the <code class="xref py py-meth docutils literal notranslate"><span class="pre">get()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> methods.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.13: </span>Added the <code class="xref py py-meth docutils literal notranslate"><span class="pre">clear()</span></code> method.</p>
<p>The following methods are also provided:</p>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.gnu.gdbm.close">
<span class="sig-prename descclassname"><span class="pre">gdbm.</span></span><span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dbm.gnu.gdbm.close" title="Link to this definition">¶</a></dt>
<dd><p>Close the GDBM database.</p>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.gnu.gdbm.firstkey">
<span class="sig-prename descclassname"><span class="pre">gdbm.</span></span><span class="sig-name descname"><span class="pre">firstkey</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dbm.gnu.gdbm.firstkey" title="Link to this definition">¶</a></dt>
<dd><p>It's possible to loop over every key in the database using this method  and the
<a class="reference internal" href="#dbm.gnu.gdbm.nextkey" title="dbm.gnu.gdbm.nextkey"><code class="xref py py-meth docutils literal notranslate"><span class="pre">nextkey()</span></code></a> method.  The traversal is ordered by GDBM's internal
hash values, and won't be sorted by the key values.  This method returns
the starting key.</p>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.gnu.gdbm.nextkey">
<span class="sig-prename descclassname"><span class="pre">gdbm.</span></span><span class="sig-name descname"><span class="pre">nextkey</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">key</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#dbm.gnu.gdbm.nextkey" title="Link to this definition">¶</a></dt>
<dd><p>Returns the key that follows <em>key</em> in the traversal.  The following code prints
every key in the database <code class="docutils literal notranslate"><span class="pre">db</span></code>, without having to create a list in memory that
contains them all:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">k</span> <span class="o">=</span> <span class="n">db</span><span class="o">.</span><span class="n">firstkey</span><span class="p">()</span>
<span class="k">while</span> <span class="n">k</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
    <span class="nb">print</span><span class="p">(</span><span class="n">k</span><span class="p">)</span>
    <span class="n">k</span> <span class="o">=</span> <span class="n">db</span><span class="o">.</span><span class="n">nextkey</span><span class="p">(</span><span class="n">k</span><span class="p">)</span>
</pre></div>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.gnu.gdbm.reorganize">
<span class="sig-prename descclassname"><span class="pre">gdbm.</span></span><span class="sig-name descname"><span class="pre">reorganize</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dbm.gnu.gdbm.reorganize" title="Link to this definition">¶</a></dt>
<dd><p>If you have carried out a lot of deletions and would like to shrink the space
used by the GDBM file, this routine will reorganize the database.  <code class="xref py py-class docutils literal notranslate"><span class="pre">gdbm</span></code>
objects will not shorten the length of a database file except by using this
reorganization; otherwise, deleted file space will be kept and reused as new
(key, value) pairs are added.</p>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.gnu.gdbm.sync">
<span class="sig-prename descclassname"><span class="pre">gdbm.</span></span><span class="sig-name descname"><span class="pre">sync</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dbm.gnu.gdbm.sync" title="Link to this definition">¶</a></dt>
<dd><p>When the database has been opened in fast mode, this method forces any
unwritten data to be written to the disk.</p>
<section id="module-dbm.ndbm">
<span id="dbm-ndbm-new-database-manager"></span><h2><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code> --- New Database Manager<a class="headerlink" href="#module-dbm.ndbm" title="Link to this heading">¶</a></h2>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/dbm/ndbm.py">Lib/dbm/ndbm.py</a></p>
<hr class="docutils" />
<p>The <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code> module provides an interface to the
<abbr title="New Database Manager">NDBM</abbr> library.
This module can be used with the &quot;classic&quot; NDBM interface or the
<abbr title="GNU dbm">GDBM</abbr> compatibility interface.</p>
<div class="admonition note">
<p class="admonition-title">توجه</p>
<p>The file formats created by <a class="reference internal" href="#module-dbm.gnu" title="dbm.gnu: GNU database manager"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code></a> and <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code> are incompatible
and can not be used interchangeably.</p>
<div class="admonition warning">
<p class="admonition-title">هشدار</p>
<p>The NDBM library shipped as part of macOS has an undocumented limitation on the
size of values, which can result in corrupted database files
when storing values larger than this limit. Reading such corrupted files can
result in a hard crash (segmentation fault).</p>
<div class="availability docutils container">
<p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">در دسترس بودن</span></a>: not Android, not iOS, not WASI.</p>
<p>This module is not supported on <a class="reference internal" href="intro.html#mobile-availability"><span class="std std-ref">mobile platforms</span></a>
or <a class="reference internal" href="intro.html#wasm-availability"><span class="std std-ref">WebAssembly platforms</span></a>.</p>
<div class="availability docutils container">
<p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">در دسترس بودن</span></a>: Unix.</p>
<dl class="py exception">
<dt class="sig sig-object py" id="dbm.ndbm.error">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">dbm.ndbm.</span></span><span class="sig-name descname"><span class="pre">error</span></span><a class="headerlink" href="#dbm.ndbm.error" title="Link to this definition">¶</a></dt>
<dd><p>Raised on <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.ndbm</span></code>-specific errors, such as I/O errors. <a class="reference internal" href="exceptions.html#KeyError" title="KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a> is raised
for general mapping errors like specifying an incorrect key.</p>
<dl class="py data">
<dt class="sig sig-object py" id="dbm.ndbm.library">
<span class="sig-prename descclassname"><span class="pre">dbm.ndbm.</span></span><span class="sig-name descname"><span class="pre">library</span></span><a class="headerlink" href="#dbm.ndbm.library" title="Link to this definition">¶</a></dt>
<dd><p>Name of the NDBM implementation library used.</p>
<dl class="py function">
<dt class="sig sig-object py" id="dbm.ndbm.open">
<span class="sig-prename descclassname"><span class="pre">dbm.ndbm.</span></span><span class="sig-name descname"><span class="pre">open</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">filename</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flag</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">'r'</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">mode</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0o666</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em><span class="sig-paren">)</span><a class="headerlink" href="#dbm.ndbm.open" title="Link to this definition">¶</a></dt>
<dd><p>Open an NDBM database and return an <code class="xref py py-class docutils literal notranslate"><span class="pre">ndbm</span></code> object.</p>
<dl class="field-list simple">
<dt class="field-odd">پارامترها<span class="colon">:</span></dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>filename</strong> (<a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>) -- The basename of the database file
(without the <code class="file docutils literal notranslate"><span class="pre">.dir</span></code> or <code class="file docutils literal notranslate"><span class="pre">.pag</span></code> extensions).</p></li>
<li><p><strong>flag</strong> (<a class="reference internal" href="stdtypes.html#str" title="str"><em>str</em></a>) -- <ul>
<li><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code> (default): Open existing database for reading only.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'w'</span></code>: Open existing database for reading and writing.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code>: Open database for reading and writing, creating it if it doesn't exist.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'n'</span></code>: Always create a new, empty database, open for reading and writing.</p></li>
<li><p><strong>mode</strong> (<a class="reference internal" href="functions.html#int" title="int"><em>int</em></a>) -- The Unix file access mode of the file (default: octal <code class="docutils literal notranslate"><span class="pre">0o666</span></code>),
used only when the database has to be created.</p></li>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.11: </span>Accepts <a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a> for filename.</p>
<p><code class="xref py py-class docutils literal notranslate"><span class="pre">ndbm</span></code> objects behave similar to mutable <a class="reference internal" href="../glossary.html#term-mapping"><span class="xref std std-term">mappings</span></a>,
but methods <code class="xref py py-meth docutils literal notranslate"><span class="pre">items()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">values()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">pop()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">popitem()</span></code>,
and <code class="xref py py-meth docutils literal notranslate"><span class="pre">update()</span></code> are not supported,
the <code class="xref py py-meth docutils literal notranslate"><span class="pre">keys()</span></code> method returns a list, and
the <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> method requires two arguments.
It also supports a &quot;closing&quot; context manager via the <a class="reference internal" href="../reference/compound_stmts.html#with"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code></a> keyword.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.2: </span>Added the <code class="xref py py-meth docutils literal notranslate"><span class="pre">get()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> methods.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.13: </span>Added the <code class="xref py py-meth docutils literal notranslate"><span class="pre">clear()</span></code> method.</p>
<p>The following method is also provided:</p>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.ndbm.ndbm.close">
<span class="sig-prename descclassname"><span class="pre">ndbm.</span></span><span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dbm.ndbm.ndbm.close" title="Link to this definition">¶</a></dt>
<dd><p>Close the NDBM database.</p>
<section id="module-dbm.dumb">
<span id="dbm-dumb-portable-dbm-implementation"></span><h2><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code> --- Portable DBM implementation<a class="headerlink" href="#module-dbm.dumb" title="Link to this heading">¶</a></h2>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/dbm/dumb.py">Lib/dbm/dumb.py</a></p>
<div class="admonition note" id="index-0">
<p class="admonition-title">توجه</p>
<p>The <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code> module is intended as a last resort fallback for the
<code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code> module when a more robust module is not available. The <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code>
module is not written for speed and is not nearly as heavily used as the other
database modules.</p>
<hr class="docutils" />
<p>The <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code> module provides a persistent <a class="reference internal" href="stdtypes.html#dict" title="dict"><code class="xref py py-class docutils literal notranslate"><span class="pre">dict</span></code></a>-like
interface which is written entirely in Python.
Unlike other <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code> backends, such as <a class="reference internal" href="#module-dbm.gnu" title="dbm.gnu: GNU database manager"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.gnu</span></code></a>, no
external library is required.</p>
<p>The <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code> module defines the following:</p>
<dl class="py exception">
<dt class="sig sig-object py" id="dbm.dumb.error">
<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">dbm.dumb.</span></span><span class="sig-name descname"><span class="pre">error</span></span><a class="headerlink" href="#dbm.dumb.error" title="Link to this definition">¶</a></dt>
<dd><p>Raised on <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code>-specific errors, such as I/O errors.  <a class="reference internal" href="exceptions.html#KeyError" title="KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a> is
raised for general mapping errors like specifying an incorrect key.</p>
<dl class="py function">
<dt class="sig sig-object py" id="dbm.dumb.open">
<span class="sig-prename descclassname"><span class="pre">dbm.dumb.</span></span><span class="sig-name descname"><span class="pre">open</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">filename</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">flag</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">'c'</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">mode</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0o666</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#dbm.dumb.open" title="Link to this definition">¶</a></dt>
<dd><p>Open a <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code> database.</p>
<dl class="field-list simple">
<dt class="field-odd">پارامترها<span class="colon">:</span></dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>filename</strong> -- <p>The basename of the database file (without extensions).
A new database creates the following files:</p>
<li><p><code class="file docutils literal notranslate"><em><span class="pre">filename</span></em><span class="pre">.dat</span></code></p></li>
<li><p><code class="file docutils literal notranslate"><em><span class="pre">filename</span></em><span class="pre">.dir</span></code></p></li>
<li><p><strong>flag</strong> (<a class="reference internal" href="stdtypes.html#str" title="str"><em>str</em></a>) -- <ul>
<li><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code>: Open existing database for reading only.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'w'</span></code>: Open existing database for reading and writing.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code> (default): Open database for reading and writing, creating it if it doesn't exist.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">'n'</span></code>: Always create a new, empty database, open for reading and writing.</p></li>
<li><p><strong>mode</strong> (<a class="reference internal" href="functions.html#int" title="int"><em>int</em></a>) -- The Unix file access mode of the file (default: octal <code class="docutils literal notranslate"><span class="pre">0o666</span></code>),
used only when the database has to be created.</p></li>
<div class="admonition warning">
<p class="admonition-title">هشدار</p>
<p>It is possible to crash the Python interpreter when loading a database
with a sufficiently large/complex entry due to stack depth limitations in
Python's AST compiler.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.5: </span><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code> always creates a new database when <em>flag</em> is <code class="docutils literal notranslate"><span class="pre">'n'</span></code>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.8: </span>A database opened read-only if <em>flag</em> is <code class="docutils literal notranslate"><span class="pre">'r'</span></code>.
A database is not created if it does not exist if <em>flag</em> is <code class="docutils literal notranslate"><span class="pre">'r'</span></code> or <code class="docutils literal notranslate"><span class="pre">'w'</span></code>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">تغییر داده شده در نسخه 3.11: </span><em>filename</em> accepts a <a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a>.</p>
<p>The returned database object behaves similar to a mutable <a class="reference internal" href="../glossary.html#term-mapping"><span class="xref std std-term">mapping</span></a>,
but the <code class="xref py py-meth docutils literal notranslate"><span class="pre">keys()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">items()</span></code> methods return lists, and
the <code class="xref py py-meth docutils literal notranslate"><span class="pre">setdefault()</span></code> method requires two arguments.
It also supports a &quot;closing&quot; context manager via the <a class="reference internal" href="../reference/compound_stmts.html#with"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code></a> keyword.</p>
<p>The following methods are also provided:</p>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.dumb.dumbdbm.close">
<span class="sig-prename descclassname"><span class="pre">dumbdbm.</span></span><span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dbm.dumb.dumbdbm.close" title="Link to this definition">¶</a></dt>
<dd><p>Close the database.</p>
<dl class="py method">
<dt class="sig sig-object py" id="dbm.dumb.dumbdbm.sync">
<span class="sig-prename descclassname"><span class="pre">dumbdbm.</span></span><span class="sig-name descname"><span class="pre">sync</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dbm.dumb.dumbdbm.sync" title="Link to this definition">¶</a></dt>
<dd><p>Synchronize the on-disk directory and data files.  This method is called
by the <a class="reference internal" href="shelve.html#shelve.Shelf.sync" title="shelve.Shelf.sync"><code class="xref py py-meth docutils literal notranslate"><span class="pre">shelve.Shelf.sync()</span></code></a> method.</p>
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<li><a class="reference internal" href="#module-dbm.sqlite3"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.sqlite3</span></code> --- SQLite backend for dbm</a></li>
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