Pass additional data to validate

CHANGELOG.rst

@@ -6,6 +6,8 @@ Next version
 
 * Fixed the config fieldsets code to work when using Django 3.0.
 * Added an unit test and docs for the ``"validate"`` config option.
+* Passed additional data to the ``"validate"`` config option. Not
+  accepting arbitrary keyword arguments is now deprecated.
 * Changed the forms administration interface to show all form options
   from the beginning. This requires a change to the ``form_fields``
   configuration option: Instead of a list it has to be a callable

form_designer/models.py

@@ -1,4 +1,5 @@
 from collections import OrderedDict
+from functools import partial
 import json
 import warnings
 
@@ -10,6 +11,7 @@
 from django.db import models
 from django.db.models.fields import BLANK_CHOICE_DASH
 from django.utils.html import format_html, format_html_join
+from django.utils.inspect import func_accepts_kwargs
 from django.utils.module_loading import import_string
 from django.utils.text import slugify
 from django.utils.translation import gettext_lazy as _
@@ -106,9 +108,18 @@ def form_class(self):
         cfg = dict(self.CONFIG_OPTIONS)
         for key, config in self.config.items():
             try:
-                validators.append(cfg[key]["validate"])
+                validator = cfg[key]["validate"]
             except KeyError:
                 pass
+            else:
+                if func_accepts_kwargs(validator):
+                    validator = partial(validator, config=config, model_instance=self)
+                else:
+                    warnings.warn(
+                        "validate of %r should accept **kwargs" % (key,),
+                        DeprecationWarning,
+                    )
+                validators.append(validator)
 
         class Form(forms.Form):
             def clean(self):

tests/testapp/test_forms.py

@@ -8,7 +8,7 @@
 from form_designer.models import Form, FormSubmission, FIELD_TYPES
 
 
-def validate_honeypot(form, data):
+def validate_honeypot(form, data, **kwargs):
     if data.get("honeypot"):
         raise forms.ValidationError("Hello honeypot")