Example

Given the following model:

from django.db import models

class Thing(models.Model):
    nested = models.JSONField(default=dict)
    array = models.JSONField(default=list)

We can create the following ModelAdmin

from django.contrib import admin
from myapp.models import Thing

@admin.register(Thing)
class AdminThing(admin.ModelAdmin):
    pass

We can add a custom form to it using the nested form to it using NestedFormField and DynamicArrayField.

from django import forms
from subforms.fields import DynamicArrayField, NestedFormField

class FizzBuzzForm(forms.Form):
    fizz = forms.CharField()
    buzz = forms.IntegerField()

class ExampleForm(forms.Form):
    foo = forms.CharField()
    bar = NestedFormField(subform=FizzBuzzForm)

class ThingForm(forms.ModelForm):

    nested = NestedFormField(subform=ExampleForm)
    array = DynamicArrayField(subfield=NestedFormField(subform=ExampleForm))

    class Meta:
        model = Thing
        fields = [
            "nested",
            "array",
        ]

This will create the following form in the admin panel:

And the data will be saved in the following from:

thing = {
    "nested": {
        "foo": "1",
        "bar": {
            "fizz": "2",
            "buzz": 3,
        },
    },
    "array": [
        {
            "foo": "4",
            "bar": {
                "fizz": "5",
                "buzz": 6,
            },
        },
        {
            "foo": "7",
            "bar": {
                "fizz": "8",
                "buzz": 9,
            },
        },
    ],
}

The nested forms will validate each of the fields, and errors will be shown like this:

Note, that currently you cannot nest DynamicArrayField inside a DynamicArrayField. If you do, you are only able to add one subitem per parent item, and the rest of the items will be treated as if they were added to additional parent items. This is likely not the behavior you want, but I currently don't have a solution for this. Pull request are welcome!