Adds a helper function to configure the render options of any given W…

…TForms widget

onegov/form/__init__.py

@@ -1,3 +1,3 @@
-from onegov.form.core import Form
+from onegov.form.core import Form, with_options
 
-__all__ = ['Form']
+__all__ = ['Form', 'with_options']

onegov/form/core.py

@@ -10,3 +10,23 @@ class Form(BaseForm):
     def submitted(self, request):
         """ Returns true if the given request is a successful post request. """
         return request.POST and self.validate()
+
+
+def with_options(widget_class, **render_options):
+    """ Takes a widget class and returns a child-instance of the widget class,
+    with the given options set on the render call.
+
+    This makes it easy to use existing WTForms widgets with custom render
+    options:
+
+    field = StringField(widget=with_options(TextArea, class_="markdown"))
+
+    """
+
+    class Widget(widget_class):
+
+        def __call__(self, *args, **kwargs):
+            render_options.update(kwargs)
+            return super(Widget, self).__call__(*args, **render_options)
+
+    return Widget()

onegov/form/tests/test_core.py

@@ -1,5 +1,6 @@
-from onegov.form import Form
+from onegov.form import Form, with_options
 from wtforms import StringField, validators
+from wtforms.widgets import TextArea
 
 
 class DummyPostData(dict):
@@ -15,6 +16,16 @@ def __init__(self, POST):
         self.POST = DummyPostData(POST)
 
 
+class DummyField(object):
+    def __init__(self, id, name, value):
+        self.id = id
+        self.name = name
+        self.value = value
+
+    def _value(self):
+        return self.value
+
+
 def test_submitted():
 
     class TestForm(Form):
@@ -25,3 +36,11 @@ class TestForm(Form):
 
     request = DummyRequest({'test': 'Test'})
     assert TestForm(request.POST).submitted(request)
+
+
+def test_with_options():
+    widget = with_options(TextArea, class_="markdown")
+    assert 'class="markdown"' in widget(DummyField('one', 'one', '1'))
+
+    widget = with_options(TextArea, class_="x")
+    assert 'class="x"' in widget(DummyField('one', 'one', '1'))