# documentação Django 2.0.8

# Código fonte para django.contrib.postgres.forms.jsonb

    import json

    from django import forms
    from django.utils.translation import gettext_lazy as _

    __all__ = ['JSONField']

    class InvalidJSONInput(str):
        pass

    class JSONString(str):
        pass

    class JSONField(forms.CharField):
        default_error_messages = {
            'invalid': _("'%(value)s' value must be valid JSON."),
        }
        widget = forms.Textarea

        def to_python(self, value):
            if self.disabled:
                return value
            if value in self.empty_values:
                return None
            elif isinstance(value, (list, dict, int, float, JSONString)):
                return value
            try:
                converted = json.loads(value)
            except ValueError:
                raise forms.ValidationError(
                    self.error_messages['invalid'],
                    code='invalid',
                    params={'value': value},
                )
            if isinstance(converted, str):
                return JSONString(converted)
            else:
                return converted

        def bound_data(self, data, initial):
            if self.disabled:
                return initial
            try:
                return json.loads(data)
            except ValueError:
                return InvalidJSONInput(data)

        def prepare_value(self, value):
            if isinstance(value, InvalidJSONInput):
                return value
            return json.dumps(value)