From 5eb92a69d174948a8ff3b1b0ffbdc343eb81212d Mon Sep 17 00:00:00 2001
From: Sylvain Viollon <sviollon@minddistrict.com>
Date: Fri, 3 Jun 2016 11:51:38 +0200
Subject: [PATCH] Ensure required field have input.

---
 CHANGES.txt                     |  4 +++-
 src/grokcore/formlib/formlib.py | 26 +++++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 35b9dba..88e2465 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -4,7 +4,9 @@ Changes
 1.10.2 (unreleased)
 -------------------
 
-- Nothing changed yet.
+- ``grok.action`` will now trigger validation errors
+  ``RequiredMissing`` for required fields that not present at all in
+  the request.
 
 
 1.10.1 (2016-02-15)
diff --git a/src/grokcore/formlib/formlib.py b/src/grokcore/formlib/formlib.py
index dde9f4c..36c1d97 100644
--- a/src/grokcore/formlib/formlib.py
+++ b/src/grokcore/formlib/formlib.py
@@ -33,11 +33,35 @@ def __call__(self, success):
 
 
 class Action(zope.formlib.form.Action):
+
+    def validate(self, data):
+        errors = super(Action, self).validate(data)
+        if errors is None:
+            errors = self.form.validate(self, data)
+        errors.extend(ensure_required_fields_have_input(
+            self.form.widgets, data))
+        return errors
+
     def success(self, data):
         if self.success_handler is not None:
             return self.success_handler(self.form, **data)
 
 
+def ensure_required_fields_have_input(widgets, data):
+    errors = []
+    for widget in widgets:
+        if not widget.context.required or widget.hasInput():
+            continue
+        name = widget.context.__name__
+        error = zope.formlib.interfaces.WidgetInputError(
+            name,
+            widget.label,
+            zope.schema.interfaces.RequiredMissing(name))
+        widget._error = error
+        errors.append(error)
+    return errors
+
+
 def Fields(*args, **kw):
     fields = []
     for key, value in kw.items():
@@ -125,7 +149,7 @@ def apply_data(context, form_fields, data, adapters=None, update=False):
 
         if update:
             if ((newvalue is not form_field) and
-                (field.get(adapter) != newvalue)):
+                    (field.get(adapter) != newvalue)):
                 field.set(adapter, newvalue)
                 changes.setdefault(interface, []).append(name)
         else: