Mercurial > p > roundup > code
comparison doc/reference.txt @ 7853:03c1b7ae3a68
issue2551328/issue2551264 unneeded next link and total_count incorrect
Fix: issue2551328 - REST results show next link if number of
results is a multiple of page size. (Found by members of
team 3 in the UMass-Boston CS682 Spring 2024 class.)
issue2551264 - REST X-Total-Count header and @total_size
count incorrect when paginated
These issues arose because we retrieved the exact number of rows
from the database as requested by the user using the @page_size
parameter. With this changeset, we retrieve up to 10 million + 1
rows from the database. If the total number of rows exceeds 10
million, we set the total_count indicators to -1 as an invalid
size. (The max number of requested rows (default 10 million +1)
can be modified by the admin through interfaces.py.)
By retrieving more data than necessary, we can calculate the
total count by adding @page_index*@page_size to the number of
rows returned by the query.
Furthermore, since we return more than @page_size rows, we can
determine the existence of a row at @page_size+1 and use that
information to determine if a next link should be
provided. Previously, a next link was returned if @page_size rows
were retrieved.
This change does not guarantee that the user will get @page_size
rows returned. Access policy filtering occurs after the rows are
returned, and discards rows inaccessible by the user.
Using the current @page_index/@page_size it would be difficult to
have the roundup code refetch data and make sure that a full
@page_size set of rows is returned. E.G. @page_size=100 and 5 of
them are dropped due to access restrictions. We then fetch 10
items and add items 1-4 and 6 (5 is inaccessible). There is no
way to calculate the new database offset at:
@page_index*@page_size + 6 from the URL. We would need to add an
@page_offset=6 or something.
This could work since the client isn't adding 1 to @page_index to
get the next page. Thanks to HATEOAS, the client just uses the
'next' url. But I am not going to cross that bridge without a
concrete use case.
This can also be handled client side by merging a short response
with the next response and re-paginating client side.
Also added extra index markers to the docs to highlight use of
interfaces.py.
| author | John Rouillard <rouilj@ieee.org> |
|---|---|
| date | Mon, 01 Apr 2024 09:57:16 -0400 |
| parents | 219fc5804345 |
| children | 047c02dfa267 |
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| 7852:9e686e3f39c1 | 7853:03c1b7ae3a68 |
|---|---|
| 1553 Generic action can be added by inheriting from ``action.Action`` | 1553 Generic action can be added by inheriting from ``action.Action`` |
| 1554 instead of ``cgi.action.Action``. | 1554 instead of ``cgi.action.Action``. |
| 1555 | 1555 |
| 1556 .. _interfaces.py: | 1556 .. _interfaces.py: |
| 1557 .. _modifying the core of Roundup: | 1557 .. _modifying the core of Roundup: |
| 1558 | |
| 1559 .. index:: single: interfaces.py; hooking into the roundup core | |
| 1558 | 1560 |
| 1559 interfaces.py - hooking into the core of Roundup | 1561 interfaces.py - hooking into the core of Roundup |
| 1560 ================================================ | 1562 ================================================ |
| 1561 | 1563 |
| 1562 There is a magic trick for hooking into the core of Roundup. Using | 1564 There is a magic trick for hooking into the core of Roundup. Using |
