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PODjango - Extending an app's model to override its manager
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  1. PODjango - Extending an app's model to override its manager
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    copied!<p>Using the <code>django-tagging</code> app as an example, I would like to change the manager of the <code>Tag</code> model so that I can replace it with an extended one:</p> <pre><code># mytagging/models.py from django.db import models from tagging.models import TagManager, Tag class MyTagManager(TagManager): def update_tags(self, obj, tag_names): # My actions return super(MyTagManager, self).update_tags(obj, tag_names) def add_tag(self, obj, tag_name): # My actions return super(MyTagManager, self).add_tag(obj, tag_name) Tag.objects = MyTagManager </code></pre> <p>Now, <code>Tag.objects = MyTagManager</code> doesn't work, nor did I expect it to, but it illustrates what I would like to accomplish. I could very well create <code>class MyTag(Tag)</code> and set the manager that way, but then it would seem that I would also have to extend every other class that uses <code>Tag</code> and change it to <code>MyTag</code>.</p> <p>I tried <code>Tag.objects = MyTagManager()</code> to initialize the class, but I get the error <code>'NoneType' object has no attribute '_meta'</code> from a query object, it appears.</p> <p>The above code renders this error when calling <code>Tag.objects.update_tags(kwargs['instance'], tags)</code> from admin page:</p> <blockquote> <p>unbound method update_tags() must be called with MyTagManager instance as first argument (got LibraryFile instance instead)</p> </blockquote> <p>The <code>LibraryFile</code> model is the one I'm attempting to tag, and should therefore be the second argument instead of first (<code>self</code> being first).</p>
 

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