Adds an Optional validator that does not ignore data and defaults to it

HISTORY.rst

@@ -1,5 +1,9 @@
 Changelog
 ---------
+
+- Adds an Optional validator that does not ignore "data" and defaults to it.
+  [href]
+
 0.30.0 (2018-01-17)
 ~~~~~~~~~~~~~~~~~~~
 

onegov/form/__init__.py

@@ -15,7 +15,6 @@
     Form,
     merge_forms,
     move_fields,
-    with_options,
 )
 from onegov.form.display import render_field
 from onegov.form.extensions import FormExtension, Extendable
@@ -32,7 +31,7 @@
 from onegov.form.parser import parse_form
 from onegov.form.parser import parse_formcode
 from onegov.form.parser import WTFormsClassBuilder
-from onegov.form.utils import decimal_range, as_internal_id
+from onegov.form.utils import decimal_range, as_internal_id, with_options
 
 __all__ = [
     'as_internal_id',

onegov/form/core.py

@@ -1,15 +1,15 @@
-import inspect
 import weakref
 
 from collections import OrderedDict
 from decimal import Decimal
 from itertools import groupby
 from onegov.form import utils
+from onegov.form.validators import StrictOptional
 from onegov.pay import Price
 from operator import itemgetter
 from wtforms import Form as BaseForm
 from wtforms.fields.html5 import EmailField
-from wtforms.validators import InputRequired, DataRequired, Optional
+from wtforms.validators import InputRequired, DataRequired
 from wtforms_components import If, Chain
 
 
@@ -216,7 +216,7 @@ def process_depends_on(self):
                     ),
                     If(
                         field.depends_on.unfulfilled,
-                        Optional()
+                        StrictOptional()
                     ),
                 )
 
@@ -534,42 +534,6 @@ def non_empty_fields(self):
             (id, field) for id, field in self.fields.items() if field.data)
 
 
-def with_options(widget, **render_options):
-    """ Takes a widget class or instance 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"))
-
-    Note: With wtforms 2.1 this is no longer necssary. Instead use the
-    render_kw parameter of the field class. This function will be deprecated
-    in a future release.
-
-    """
-
-    if inspect.isclass(widget):
-        class Widget(widget):
-
-            def __call__(self, *args, **kwargs):
-                render_options.update(kwargs)
-                return super().__call__(*args, **render_options)
-
-        return Widget()
-    else:
-        class Widget(widget.__class__):
-
-            def __init__(self):
-                self.__dict__.update(widget.__dict__)
-
-            def __call__(self, *args, **kwargs):
-                render_options.update(kwargs)
-                return widget.__call__(*args, **render_options)
-
-        return Widget()
-
-
 class FieldDependency(object):
     """ Defines a dependency to a field. The given field(s) must have the given
     choice for this dependency to be fulfilled.

onegov/form/parser/form.py

@@ -2,14 +2,15 @@
 from onegov.form import errors
 from onegov.form.core import FieldDependency
 from onegov.form.core import Form
-from onegov.form.core import with_options
 from onegov.form.fields import MultiCheckboxField
 from onegov.form.fields import UploadField
 from onegov.form.parser.core import parse_formcode
 from onegov.form.utils import as_internal_id
+from onegov.form.utils import with_options
 from onegov.form.validators import ExpectedExtensions
 from onegov.form.validators import FileSizeLimit
 from onegov.form.validators import Stdnum
+from onegov.form.validators import StrictOptional
 from wtforms import PasswordField
 from wtforms import RadioField
 from wtforms import StringField
@@ -23,7 +24,6 @@
 from wtforms.validators import DataRequired
 from wtforms.validators import Length
 from wtforms.validators import NumberRange
-from wtforms.validators import Optional
 from wtforms.validators import Regexp
 from wtforms.validators import URL
 from wtforms.widgets import TextArea
@@ -180,7 +180,9 @@ def handle_field(builder, field, dependency=None):
             required=field.required,
             choices=[(c.key, c.label) for c in field.choices],
             default=next((c.key for c in field.choices if c.selected), None),
-            pricing=field.pricing
+            pricing=field.pricing,
+            # do not coerce None into 'None'
+            coerce=lambda v: str(v) if v is not None else v
         )
 
     elif field.type == 'checkbox':
@@ -192,7 +194,9 @@ def handle_field(builder, field, dependency=None):
             required=field.required,
             choices=[(c.key, c.label) for c in field.choices],
             default=[c.key for c in field.choices if c.selected],
-            pricing=field.pricing
+            pricing=field.pricing,
+            # do not coerce None into 'None'
+            coerce=lambda v: str(v) if v is not None else v
         )
 
     elif field.type == 'integer_range':
@@ -287,7 +291,7 @@ def validators_add_dependency(self, validators, dependency):
         validators.insert(0, validator)
 
     def validators_add_optional(self, validators):
-        validators.insert(0, Optional())
+        validators.insert(0, StrictOptional())
 
     def mark_as_dependent(self, field_id, dependency):
         field = getattr(self.form_class, field_id)

onegov/form/utils.py

@@ -1,3 +1,4 @@
+import inspect
 import re
 
 from decimal import Decimal
@@ -86,3 +87,39 @@ def __next__(self):
 
 def hash_definition(definition):
     return md5(definition.encode('utf-8')).hexdigest()
+
+
+def with_options(widget, **render_options):
+    """ Takes a widget class or instance 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"))
+
+    Note: With wtforms 2.1 this is no longer necssary. Instead use the
+    render_kw parameter of the field class. This function will be deprecated
+    in a future release.
+
+    """
+
+    if inspect.isclass(widget):
+        class Widget(widget):
+
+            def __call__(self, *args, **kwargs):
+                render_options.update(kwargs)
+                return super().__call__(*args, **render_options)
+
+        return Widget()
+    else:
+        class Widget(widget.__class__):
+
+            def __init__(self):
+                self.__dict__.update(widget.__dict__)
+
+            def __call__(self, *args, **kwargs):
+                render_options.update(kwargs)
+                return widget.__call__(*args, **render_options)
+
+        return Widget()

onegov/form/validators.py

@@ -1,12 +1,16 @@
 import importlib
 import humanize
 
+from cgi import FieldStorage
 from mimetypes import types_map
 from onegov.form import _
-from onegov.form.core import with_options
+from onegov.form.utils import with_options
 from onegov.form.errors import InvalidFormSyntax, DuplicateLabelError
 from stdnum.exceptions import ValidationError as StdnumValidationError
 from wtforms import ValidationError
+from wtforms.fields import SelectField
+from wtforms.validators import StopValidation, Optional
+from wtforms.compat import string_types
 
 
 class Stdnum(object):
@@ -152,3 +156,38 @@ def __call__(self, form, field):
                                     label=formfield.label.text
                                 )
                             )
+
+
+class StrictOptional(Optional):
+    """ A copy of wtform's Optional validator, but with a more strict approach
+    to optional validation checking.
+
+    See https://github.com/wtforms/wtforms/issues/350
+
+    """
+
+    def is_missing(self, value):
+        if isinstance(value, FieldStorage):
+            return False
+
+        if not value:
+            return True
+
+        if isinstance(value, string_types):
+            return not self.string_check(value)
+
+        return False
+
+    def __call__(self, form, field):
+        raw = field.raw_data and field.raw_data[0]
+        val = field.data
+
+        # the selectfields have this annyoing habit of coercing all values
+        # that are added to them -> this includes the None, which is turned
+        # into 'None'
+        if isinstance(field, SelectField) and val == 'None':
+            val = None
+
+        if self.is_missing(raw) and self.is_missing(val):
+            field.errors[:] = []
+            raise StopValidation()