Create dynamic fields in ModelForm (Django)

Question

How do I create fields in ModelForm on the go?

For example, I want to create 3 textboxes (because there are 3 entries in the database table)

 ID  Name   Value 
------------------
 1   Alpha  10   
 2   Beta   91    
 3   Char   800

How do I display it in this way to the user? Does it involve the _init definition? Is it possible to do a for loop of objects in your model form class to retrieve its values and convert them to a field to be displayed? Appreciate any suggestions.

Alpha 

[textbox]
______
Beta

[textbox]

____

etc..

[Submit]

Here is what I tried to do in the def init of the modelform:

self.fields['myfield'].widget = forms.Textarea()

Can't seem to give me the output, do mind my weak understanding of certain django concepts.

emyller · Accepted Answer · 2011-05-16 04:29:29Z

18

I think that your best bet is, in this case, to stick to Model formsets. For any other case, you can just append new fields to the fields attribute, inside your form's __init__.

def __init__(self, *args, *kwargs):
    super(MyForm, self).__init__(*args, **kwargs)
    self.fields.update({
        'foo': forms.CharField(widget=forms.Textarea()),
        'bar': forms.CharField(widget=forms.Textarea()),
    })

Remember that, in this case, you have to call the parent's __init__ first, so you'll have the .fields available.

edited May 16, 2011 at 4:29

answered May 16, 2011 at 4:23

emyller

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1 Comment

Daniel Roseman Over a year ago

Formsets are the simple answer here.

Max Peterson · Accepted Answer · 2013-01-29 16:54:20Z

7

You can also dynamically define form fields using the django.forms.models.ModelFormMetaclass (used by django.forms.models.modelform_factory). This will create a ModelForm class using the fields you specify rather than updating the fields 'on the fly' in the init.

from django import forms
from django.forms.models import ModelForm, ModelFormMetaclass


model = MyModel
fields = {
    'myfield': forms.CharField(widget=forms.Textarea())
}

meta_attrs = {
    'model': model,
}

Meta = type('Meta', (object, ), meta_attrs)

form_class_attrs = {
    'Meta': Meta, 
}

form_class_attrs.update(fields)

MyModelForm = ModelFormMetaclass('MyModelForm', (ModelForm, ), form_class_attrs)

answered Jan 29, 2013 at 16:54

Max Peterson

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Comments

Henry · Accepted Answer · 2011-05-16 02:49:33Z

3

Yes you want to override the __init__, something like:

def __init__(self, *args, **kwargs):
    super(MyModelForm, self).__init__(*args, **kwargs)
    for foo, bar in jelly:
        self.fields[foo] = forms.CharField(widget=forms.Textarea())

See lots more info here - it all pretty much applies to ModelForm as well.

answered May 16, 2011 at 2:49

Henry

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1 Comment

Vikram Over a year ago

You can add queryset to the forms.CharField to get retrieve the values from database dynamically

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