Added WtfBaseField. This is a sub-class of

mongoengine.base.fields.BaseField - it provides flask-mongoengine wtf to
extend on the field parameters and settings on behalf of wtf model form
generator.

We achieve this by monkey patch all mongoengine fields classes whose
base class is BaseField at __init__ of flask-mongoengine.

Feature:

Author: losintikfos

flask_mongoengine/__init__.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import
+import inspect
 
 from flask import abort, current_app
 
@@ -13,6 +14,45 @@
 from .sessions import *
 from .pagination import *
 from .json import overide_json_encoder
+from .wtf import WtfBaseField
+
+
+def _patch_base_field(object, name):
+    """
+    If the object submitted has a class whose base class is
+    mongoengine.base.fields.BaseField, then monkey patch to
+    replace it with flask_mongoengine.wtf.WtfBaseField.
+
+    @note:  WtfBaseField is an instance of BaseField - but
+            gives us the flexibility to extend field parameters
+            and settings required of WTForm via model form generator.
+
+    @see: flask_mongoengine.wtf.base.WtfBaseField.
+    @see: model_form in flask_mongoengine.wtf.orm
+
+    @param object:  The object whose footprint to locate the class.
+    @param name:    Name of the class to locate.
+
+    """
+    # locate class
+    cls = getattr(object, name)
+    if not inspect.isclass(cls):
+        return
+
+    # fetch class base classes
+    cls_bases = list(cls.__bases__)
+
+    # replace BaseField with WtfBaseField
+    for index, base in enumerate(cls_bases):
+        if base == mongoengine.base.fields.BaseField:
+            cls_bases[index] = WtfBaseField
+            cls.__bases__ = tuple(cls_bases)
+            break
+
+    # re-assign class back to
+    # object footprint
+    delattr(object, name)
+    setattr(object, name, cls)
 
 
 def _include_mongoengine(obj):
@@ -21,6 +61,9 @@ def _include_mongoengine(obj):
             if not hasattr(obj, key):
                 setattr(obj, key, getattr(module, key))
 
+                # patch BaseField if available
+                _patch_base_field(obj, key)
+
 
 def _create_connection(conn_settings):
 
@@ -44,10 +87,10 @@ def _create_connection(conn_settings):
     return mongoengine.connect(conn.pop('db', 'test'), **conn)
 
 
+
 class MongoEngine(object):
 
     def __init__(self, app=None, config=None):
-
         _include_mongoengine(self)
 
         self.Document = Document

flask_mongoengine/wtf/__init__.py

@@ -1 +1,2 @@
 from flask.ext.mongoengine.wtf.orm import model_fields, model_form
+from flask.ext.mongoengine.wtf.base import WtfBaseField

flask_mongoengine/wtf/base.py

@@ -0,0 +1,26 @@
+from mongoengine.base import BaseField
+
+__all__ = ('WtfBaseField')
+
+class WtfBaseField(BaseField):
+    """
+    Extension wrapper class for mongoengine BaseField.
+
+    This enables flask-mongoengine  wtf to extend the
+    number of field parameters, and settings on behalf
+    of document model form generator for WTForm.
+
+    """
+
+    def __init__(self, validators=None, **kwargs):
+        BaseField.__init__(self, **kwargs)
+
+        # Ensure we have a list of validators
+        if validators is not None:
+            if callable(validators):
+                validators = [validators]
+            else:
+                msg = "Argument 'validators' must be a list value"
+                if not isinstance(validators, list):
+                    raise TypeError(msg)
+        self.validators = validators