Use variable as form fields in Django form template

Question

<here all loading of static , template_filters, crispy_forms >

<form>
{% for i in artifact_length %}
   {% with artifact_name="artifact"|artifact_name:forloop.counter0 %}
        {{form.artifact_name|as_crispy_field}}
   {% endwith %}
{%endfor%}
</form>

This is related template code. Here i want to render form fields with names artifact_0, artifact_1 as coming from form. The variable artifact_name inside with is working fine and returning expected identifiers artifact_0 , artifact_1, but i want to use these variables as form fields to render as as_crispy_field. The code {{form.artifact_name|as_crispy_field}} does not print anything because it is assuming form as field with name artifact_name which is not. Instead i want to use the value of variable here.

forms.py

  class Someform(forms.form):
    def __init__(self, artifact_obj):
        super().__init__()
        count = 0
        for artifact in artifact_obj:
            self.fields[f'artifact_{count}'] = forms.CharField(widget=forms.NumberInput())
                count += 1

tags.py

@register.filter('artifact_name')
def get_artifact_name(artifact_prefix: str, counter: int):
    print('method', 'prefix', artifact_prefix, 'counter', counter)
    return f'{artifact_prefix}_{counter}'

There is variable length form being created. As informs.py form fields are being created with artifact_count where count can range from 0 to len of obj.

Are those the only fields in your form and is len(artifact_obj) the same as artifact_length? — Abdul Aziz Barkat
– Abdul Aziz Barkat, Commented Nov 27, 2021 at 9:18
there are more fields , i could rander them by name. But these are variable fields and cant estimate how much it will be. Need loop to iterate. . Yes, artifact_length is same as artifact_obj. — John Byro
– John Byro, Commented Nov 27, 2021 at 9:20
it is being passed in context as {'artifact_length':range(len(artifact_obj))} — John Byro
– John Byro, Commented Nov 27, 2021 at 9:21
What about the order you want to render the other fields in? — Abdul Aziz Barkat
– Abdul Aziz Barkat, Commented Nov 27, 2021 at 9:21
Order does not matter , i just rendered them above all these variable fields. Now need to render these fields too — John Byro
– John Byro, Commented Nov 27, 2021 at 9:21

Abdul Aziz Barkat · Accepted Answer · 2021-11-27 10:37:05Z

1

You don't need to use filters / template tags, etc. for this purpose. The simplest solution would be to loop over the form fields to render them:

<form>
{% for field in form %}
    {{ field|as_crispy_field }}
{%endfor%}
</form>

This will loop over all the fields in your form.

If you particularly care about the order of these fields you can call the forms order_fields method:

class Someform(forms.form):
    def __init__(self, artifact_obj, *args, **kwargs):
        super().__init__(*args, **kwargs)
        for count, artifact in enumerate(artifact_obj):
            self.fields[f'artifact_{count}'] = forms.CharField(widget=forms.NumberInput())
        self.order_fields(["field_1", "field_2", ...] + [f"artifact_{i}" for i, _ in enumerate(artifact_obj)] + [..., "field_n"])

If you particularly want to render the other fields separately you can add a method to your form that will allow you to loop over these fields:

class Someform(forms.form):
    def __init__(self, artifact_obj, *args, **kwargs):
        super().__init__(*args, **kwargs)
        for count, artifact in enumerate(artifact_obj):
            self.fields[f'artifact_{count}'] = forms.CharField(widget=forms.NumberInput())
        self.artifact_length = len(artifact_obj)
    
    def artifact_fields(self):
        return [self[f'artifact_{i}'] for i in range(self.artifact_length)]

And then loop over these in the template:

<form>
{% for field in form.artifact_fields %}
    {{ field|as_crispy_field }}
{%endfor%}
</form>

edited Nov 27, 2021 at 10:37

answered Nov 27, 2021 at 9:35

Abdul Aziz Barkat

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4 Comments

John Byro Over a year ago

Thanks a lot. It works. I found a workaround by having template tags, filters but that much lengthy. Having addiional method to print artifact is a good idea.

John Byro Over a year ago

there is one error now . When i submit the form and did this if request.method == 'POST': form = Someform(request.POST) if form.is_valid(): It throw error now, which i could understand as constructor taking artifact_obj and it got request.POST. How to resolve this? Do i need to have args and **kwargs?

Abdul Aziz Barkat Over a year ago

@JohnByro see my edit, yes you should use *args, **kwargs. Also you should pass artifact_obj regardless of the request method so Someform(artifact_obj, request.POST)

John Byro Over a year ago

can you suggest how can we delete the fields dynamically , as we added them in above post.?

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