38 lines
1.5 KiB
Markdown
38 lines
1.5 KiB
Markdown
I'm setting up a testing environment for work, using fixtures to save
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and load test data and I got a little stumped by something I ran into.
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I had exported one of the database tables we use to a json file that I
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was going to import into a fresh new database to test with. When I
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imported it everything seemed fine, except when looking at the actual
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page. So this is what I found:
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<pre class="src src-sql">SELECT * FROM app_table;
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=> 3 rows of data</pre>
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<pre class="src src-python"><span class="org-keyword">from</span> app.models <span class="org-keyword">import</span> Table
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Table.objects.count()
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=> 3
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Table.objects.<span class="org-builtin">all</span>()
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=> []</pre>
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This is weird. So I looked at the `django.db.connection.queries`
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property and I realized that it was doing a join since the model
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subclasses another:
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<pre class="src src-python"><span class="org-keyword">from</span> django.db <span class="org-keyword">import</span> models
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<span class="org-keyword">from</span> app.models <span class="org-keyword">import</span> SuperTable
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<span class="org-keyword">class</span> <span class="org-type">Table</span>(SuperTable):...</pre>
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Which, of course, means that in order to get the complete `Table`
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instance, the related `SuperTable` instance is also required, but in
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order to do a `COUNT` of `app_table` it isn't necessary. And that's
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where the inconsistency came from, now that I've also copied the
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contents of `SuperTable` everything is fine again.
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[[!meta date="2012-04-24 15:51:00"]]
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[[!tag python django coding]]
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