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PODjango no entry in many to many table
 

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  1. PODjango no entry in many to many table
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    <p>I have a problem with django that I really cant get my head around. Been stuck on it for two days and been looking in the source but I cant find any explanation, hopefully someone knows this better than I do!</p> <p>I have two models, <code>Publication</code> and <code>Article</code> like this</p> <pre><code>class Publication(models.Model): title = models.CharField(max_length=30) articles = models.ManyToManyField('Article',blank=True) class Meta: db_table = 'publications' class Article(models.Model): headline = models.CharField(max_length=100) class Meta: db_table = 'articles' </code></pre> <p>When I save a new <code>Publication</code> I want to automatically save a default article. I did a script to test this and it works fine. Both objects are created in their respective tables and one entry is written to the <code>publications_articles</code> table. As expected.</p> <pre><code>publication = Publication(title='The new exciting publication') publication.save() publication.articles.create(headline='The article that makes the pub so exciting') </code></pre> <p>However, here is the tricky part. To have the same functionality when saving a <code>Publication</code> in the admin I did override the <code>save_model()</code> function like this.</p> <pre><code>class PublicationAdmin(admin.ModelAdmin): list_display = ['title'] def save_model(self, request, obj, form, change): if not change: obj.save() obj.articles.create(headline='The article that makes this pub so exciting') else: obj.save() </code></pre> <p>Saving a <code>Publication</code> in the admin creates both the <code>Publication</code> and the <code>Article</code> but theres no entry in the <code>publications_articles</code> table tying them together! </p> <p>Someone please, please explain this behavior. I'm about to do a raw sql-insert just to get through with it but I want to understand why the connection between the entities is not made.</p>
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    1. This table or related slice is empty.
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    1. USGesias
    1. USGesias
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
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    1. This table or related slice is empty.
    1. COare you sure that the flow enters `if not change:` case?
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      1. USBabu
    2. COI've ran your code (with the addition of `admin.site.register(Publication, PublicationAdmin)` and it works like charm (Django version 1.3.4, Python 2.6). Could it be that there is more code that might prevent your code from working? Try to add some `print "test"` statements to your `save_model(...)` and see if the code is actually executed. Another test: insert `print obj.pk` inbetween `obj.save()` and `obj.articles.create(..`
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      1. PODjango no entry in many to many table
      1. USWouter Klein Heerenbrink
    3. COProbably, he should have missed the `admin.site.register` part.
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      1. PODjango no entry in many to many table
      1. USBabu
 

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A row detail

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.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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