Merge pull request #267 from gliptak/dbexception1

mperry · mperry · commit 12b6163ea6f8 · 2016-06-08T10:40:54.000+10:00
Add DB.db method with Try1
diff --git a/core/src/main/java/fj/control/db/DB.java b/core/src/main/java/fj/control/db/DB.java
@@ -2,6 +2,7 @@
 
 import fj.F;
 import fj.Function;
+import fj.function.Try1;
 
 import java.sql.Connection;
 import java.sql.SQLException;
@@ -35,6 +36,21 @@ public A run(final Connection c) {
     };
   }
 
+  /**
+   * Constructs a database action as a function from a database connection to a value.
+   *
+   * @param t A function from a database connection to a value allowed to throw
+   *          SQLException
+   * @return A database action representing the given function.
+   */
+  public static <A> DB<A> db(final Try1<Connection, A, SQLException> t){
+    return new DB<A>() {
+      public A run(final Connection c) throws SQLException {
+        return t.f(c);
+      }
+    };
+  }
+
   /**
    * Returns the callable-valued function projection of this database action.
    *
diff --git a/core/src/test/java/fj/control/db/TestDbState.java b/core/src/test/java/fj/control/db/TestDbState.java
@@ -2,6 +2,7 @@
 
 import fj.Unit;
 import fj.data.Option;
+import fj.function.Try1;
 import org.apache.commons.dbutils.DbUtils;
 import org.junit.Test;
 
@@ -16,20 +17,18 @@ public void testWriter() throws SQLException {
         final int TEN = 10;
         DbState writer = DbState.writer(DbState.driverManager("jdbc:h2:mem:"));
 
-        DB<Unit> setup = new DB<Unit>() {
-            @Override
-            public Unit run(Connection c) throws SQLException {
-                Statement s = null;
-                try {
-                    s = c.createStatement();
-                    assertThat(s.executeUpdate("CREATE TABLE TEST(ID INT PRIMARY KEY, NAME VARCHAR(255))"), is(0));
-                    assertThat(s.executeUpdate("INSERT INTO TEST (ID, NAME) VALUES (" + TEN + ", 'FOO')"), is(1));
-                } finally {
-                    DbUtils.closeQuietly(s);
-                }
-                return Unit.unit();
+        DB<Unit> setup = DB.db((Try1<Connection, Unit, SQLException>) c -> {
+            Statement s = null;
+            try {
+                s = c.createStatement();
+                assertThat(s.executeUpdate("CREATE TABLE TEST(ID INT PRIMARY KEY, NAME VARCHAR(255))"), is(0));
+                assertThat(s.executeUpdate("INSERT INTO TEST (ID, NAME) VALUES (" + TEN + ", 'FOO')"), is(1));
+            } finally {
+                DbUtils.closeQuietly(s);
             }
-        };
+            return Unit.unit();
+        });
+
         DB<Option<Integer>> query = new DB<Option<Integer>>() {
             @Override
             public Option<Integer> run(Connection c) throws SQLException {
