Databases
StackOverflow2013
Postsdbo
POModels unique_together constraint + None = fail?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POModels unique_together constraint + None = fail?
    primarykey
    data
    text
    <p>2 questions:</p> <ul> <li>How can I stop duplicates from being created when parent=None and name is the same?</li> <li>Can i call a model method from within the form? </li> </ul> <p>Please see full details below:</p> <h1>models.py</h1> <pre><code>class MyTest(models.Model): parent = models.ForeignKey('self', null=True, blank=True, related_name='children') name = models.CharField(max_length=50) slug = models.SlugField(max_length=255, blank=True, unique=True) owner = models.ForeignKey(User, null=True) class Meta: unique_together = ("parent", "name") def save(self, *args, **kwargs): self.slug = self.make_slug() super(MyTest, self).save(*args, **kwargs) def make_slug(self): # some stuff here return generated_slug </code></pre> <p>note: slug = unique as well!</p> <h1>forms.py</h1> <pre><code>class MyTestForm(forms.ModelForm): class Meta: model = MyTest exclude = ('slug',) def clean_name(self): name = self.cleaned_data.get("name") parent = self.cleaned_data.get("parent") if parent is None: # this doesn't work when MODIFYING existing elements! if len(MyTest.objects.filter(name = name, parent = None)) &gt; 0: raise forms.ValidationError("name not unique") return name </code></pre> <h1>Details</h1> <p>The <code>unique_together</code> contraint works perfectly w/ the form when <code>parent != None</code>. However when <code>parent == None</code> (null) it allows duplicates to be created.</p> <p>In order to try and avoid this, i tried using the form and defined clean_name to attempt to check for duplicates. This works when <em>creating</em> new objects, but doesn't work when modifying existing objects.</p> <p>Someone had mentioned i should use commit=False on the ModelForm's .save, but I couldn't figure out how to do/implement this. I also thought about using the ModelForm's has_changed to detect changes to a model and allow them, but has_changed returns true on newly created objects with the form as well. help!</p> <p>Also, (somewhat a completely different question) can I access the make_slug() model method from the Form? I <em>believe</em> that currently my <code>exclude = ('slug',)</code> line is also ignoring the 'unique' constraint on the slug field, and in the models save field, I'm generating the slug instead. I was wondering if i could do this in the forms.py instead?</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USlostincode
    1. USlostincode
    plurals
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POModels unique_together constraint + None = fail?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POModels unique_together constraint + None = fail?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POModels unique_together constraint + None = fail?
      1. USDon
      1. VTFavorite
    1. COSee http://stackoverflow.com/questions/3488264/django-unique-together-doesnt-work-with-foreignkey-none for an up to date method of handling this issue. Requires Django 1.2.
      singulars
      1. POModels unique_together constraint + None = fail?
      1. USFaheem Mitha
 

Querying!

 
Guidance
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.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload