http://dev.clojure.org/jira This file is an XML representation of an issue en-us 4.4 649 25-07-2011 http://dev.clojure.org/jira/browse/JDBC-46 java.jdbc <p>I had this idea when trying to adapt Korma to use with postgres tables with columns of array types. I had some success using Korma's transform functions to convert the java.sql.Array objects into a seq on the way out, but recent changes to Korma seem to indicate that the transform functions are not guaranteed to run before the connection is closed. This interferes with efforts to read the arrays, which I think can be their own result sets.</p> <p>Presumably korma could be changed to support reading the arrays on the way out, but maybe being able to customize the read behavior within c.j.jdbc would be simpler.</p> <p>The first idea I've had toward this end is to create a protocol with a single function that objects being read out of the resultset get passed through. It would default to the identity function, but users could e.g. extend it to java.sql.Array. I don't know if there are significant performance implications for an extra function call for each value coming out of the database.</p> <p>I'll have a patch in this vein attached shortly.</p> JDBC-46

A mechanism for reading specialized types from result sets could be useful

Enhancement Major Resolved Completed Sean Corfield Gary Fredericks Wed, 23 Jan 2013 09:23:06 -0600 Wed, 15 May 2013 09:52:03 -0500 Fri, 19 Apr 2013 21:34:49 -0500 0 0 <p>Attached patch. Is there any straightforward way to test this? Or a place it should be documented?</p> <p>Docs: just needs good docstring since the clojure.github.com site is auto-generated from those (although it is still triggered manually it seems).</p> <p>Test: mvn test</p> <p>I have Derby, HSQLDB, MySQL, MS SQL Server (two drivers), MySQL. I don't have Postgres to test against. By default mvn test only tries Derby, HSQLDB and SQLite. TEST_DBS=... mvn test will test more.</p> <p>Would be nice to have a test with a custom conversion, mapping any String to some constant perhaps? Perhaps a separate test ns that is required and tested from test_jdbc.clj?</p> <p>Oh, we have to be careful with testing because I believe any extensions to the protocol are going to be effective for all the remaining tests, right?</p> <p>Attached new patch with docstrings and a test. I've only run the tests with MySQL. Let me know if there's anything else I can do.</p> <p>This patch recently came in handy in an different situation, when jdbc was returning Integers instead of Longs, we had a really clean spot to do the conversion.</p> <p>There have been a lot of code changes since you submitted the patch and right now the patch doesn't apply. Can you re-submit the patch against the latest master branch so I can try again? Thanx!</p> <p>I'm getting 3 test failures on master currently (with a basic <tt>mvn test</tt>), and after applying this new patch (p3) I still get 3 failures. So hopefully that means I didn't break anything.</p> <p>Applied. Will be in 0.3.0-alpha2</p> <p>I'm thinking this feature is no longer necessary due to the :row-fn option &#8211; since the only motivation in the first place was to have the opportunity to transform a result before the connection closes.</p> <p>There would still be no easy way to do it from Korma, but that's Korma's fault. So maybe we should remove this before 0.3.0 is released?</p> Global Rank