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Editorial Team
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Asked: 2026-06-02T16:07:46+00:00

so new to python & django moving along nice on a project but cant

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so new to python & django moving along nice on a project but cant find any simple answers to the above question:

Models are like this 

class Projects(models.Model):
    project_name = models.CharField(max_length=200)
    project_description = models.TextField(blank=True)    
    active = models.BooleanField() 

    def __unicode__(self):
        return self.project_name

I have other models that refer to the above as a ForignKey like

class Estimates(models.Model):
    client = models.ForeignKey(Clients)
    estimate_summary = models.CharField(max_length=200,blank=True)
    project = models.ForeignKey(Projects,default=-1,blank=True)

I know I can set blank=False to ensure I am getting a valid choice, however I want to allow them the option of not assigning a project to the estimate, in which case I would store a default integer -1 or something.

Problem however is I cant figure how to get the form to use an Integer as its default value instead of ” ” <- (empty string)

<option selected="selected" value="">---------</option>
<option value="1">Sample Project</option>

All the questions and answers I have seen revolve around changing the --------- to some other text or forcing you to remove the blank option all together. I just want 

<option selected="selected" value="-1">---------</option>

So my form will validate

When finished writing the question I wondered if I could insert an option myself and use empty_label=None when adding to the form

field2 = forms.ModelChoiceField(queryset=..., empty_label=None)
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1 Answer

  1. Editorial Team

    First of all, you don’t want to use an Integer of -1 as default. For ForeignKeys you usually use null=True in combination with blank=True if you don’t require it (Don’t forget to drop and recreate the table or use south to migrate it — also remove default then since None is a valid option with null=True and as such no default is required). This way if you don’t assign a project you will get NULL in the database which is also what the Admin supports — -1 will break more than it solves.

    As soon as you use null=True, blank=True ModelChoiceField will automatically work as you want.

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