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    <p>When you save a model via admin forms it's not an atomic transaction. The main object gets saved first (to make sure it has a PK), then the M2M is <strong><em>cleared</em></strong> and the new values set to whatever came out of the form. So if you are in the save() of the main object you are in a window of opportunity where the M2M hasn't been updated yet. In fact, if you <em>try</em> to do something to the M2M, the change will get wiped out by the clear(). I ran into this about a year ago.</p> <p>The code has changed somewhat from the pre-ORM refactor days, but it boils down to code in <code>django.db.models.fields.ManyRelatedObjectsDescriptor</code> and <code>ReverseManyRelatedObjectsDescriptor</code>. Look at their __set__() methods and you'll see <code>manager.clear(); manager.add(*value)</code> That clear() complete cleans out any M2M references for the current main object in that table. The add() then sets the new values.</p> <p>So to answer your question: yes, this is a transaction issue.</p> <p>Is there a signal thrown when the transaction ends? Nothing official, but read on:</p> <p>There was a <a href="https://stackoverflow.com/questions/950214/run-code-after-transaction-commit-in-django">related thread a few months ago</a> and MonkeyPatching was one method proposed. <a href="https://stackoverflow.com/questions/950214/run-code-after-transaction-commit-in-django/1837402#1837402">Grégoire posted a MonkeyPatch</a> for this. I haven't tried it, but it looks like it should work.</p>
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    1. POIssue with ManyToMany Relationships not updating immediately after save
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    1. USPeter Rowell
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    1. COI ran into this problem as well, I used a solution found here http://stackoverflow.com/questions/6200233/manytomany-field-not-saved-when-using-django-admin
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      1. USDaniel Backman
 

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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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