Adds an ordered multi checkbox field

HISTORY.rst

@@ -1,5 +1,9 @@
 Changelog
 ---------
+
+- Adds an ordered multi checkbox field.
+  [href]
+
 0.14.0 (2016-09-09)
 ~~~~~~~~~~~~~~~~~~~
 

onegov/form/fields.py

@@ -3,7 +3,9 @@
 import magic
 
 from io import BytesIO
-from onegov.form.widgets import MultiCheckboxWidget, UploadWidget
+from onegov.form.widgets import MultiCheckboxWidget
+from onegov.form.widgets import OrderedMultiCheckboxWidget
+from onegov.form.widgets import UploadWidget
 from wtforms import FileField, SelectMultipleField, widgets
 
 
@@ -17,6 +19,10 @@ def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
 
+class OrderedMultiCheckboxField(MultiCheckboxField):
+    widget = OrderedMultiCheckboxWidget()
+
+
 class UploadField(FileField):
     """ A custom file field that turns the uploaded file into a compressed
     base64 string together with the filename, size and mimetype.

onegov/form/tests/test_fields.py

@@ -1,10 +1,13 @@
 import base64
+import re
 import tempfile
 
 from cgi import FieldStorage
 from gzip import GzipFile
 from io import BytesIO
 from onegov.form import Form
+from onegov.form.fields import MultiCheckboxField
+from onegov.form.fields import OrderedMultiCheckboxField
 from onegov.form.fields import UploadField
 
 
@@ -35,3 +38,32 @@ def decompress(data):
             return f.read()
 
     assert decompress(base64.b64decode(data['data'])) == b'foobar'
+
+
+def test_ordered_multi_checkbox_field():
+    ordinary = MultiCheckboxField(choices=[
+        ('c', 'C'),
+        ('b', 'B'),
+        ('a', 'A')
+    ])
+    ordered = OrderedMultiCheckboxField(choices=[
+        ('c', 'C'),
+        ('b', 'B'),
+        ('a', 'A')
+    ])
+    ordinary = ordinary.bind(Form(), 'choices')
+    ordered = ordered.bind(Form(), 'choices')
+
+    ordinary.data = ordered.data = []
+
+    assert re.findall(r'value="((a|b|c){1})"', ordinary()) == [
+        ('c', 'c'),
+        ('b', 'b'),
+        ('a', 'a'),
+    ]
+
+    assert re.findall(r'value="((a|b|c){1})"', ordered()) == [
+        ('a', 'a'),
+        ('b', 'b'),
+        ('c', 'c'),
+    ]

onegov/form/widgets.py

@@ -6,14 +6,50 @@
 from wtforms.widgets.core import HTMLString
 
 
+class OrderedListWidget(ListWidget):
+    """ Extends the default list widget with automated ordering using the
+    translated text of each element.
+
+    """
+
+    def __call__(self, field, **kwargs):
+
+        # ListWidget expects a field internally, but it will only use
+        # its id property and __iter__ method, so we can get away
+        # with passing a fake field with an id and an iterator.
+        #
+        # It's not great, since we have to assume internal knowledge,
+        # but builting a new field or changing the existing one would
+        # require even more knowledge, so this is the better approach
+        #
+        # We also need to call each field once so it gets hooked up with
+        # our translation machinary
+        ordered = [subfield for subfield in field]
+        ordered.sort(key=lambda f: (f(), str(f.label.text))[1])
+
+        class FakeField(object):
+
+            id = field.id
+
+            def __iter__(self):
+                return iter(ordered)
+
+        return super().__call__(FakeField(), **kwargs)
+
+
 class MultiCheckboxWidget(ListWidget):
-    """ The default wtforms ListWidget, extended different default values. """
+    """ The default list widget with the label behind the checkbox. """
 
     def __init__(self, *args, **kwargs):
         kwargs['prefix_label'] = False
         super().__init__(*args, **kwargs)
 
 
+class OrderedMultiCheckboxWidget(MultiCheckboxWidget, OrderedListWidget):
+    """ The sorted list widget with the label behind the checkbox. """
+    pass
+
+
 class CoordinateWidget(TextInput):
     """ Widget containing the coordinates for the
     :class:`onegov.form.fields.CoordinateField` class.