Merge pull request #1129 from illico/feature/arbitrary-metadata

Indirection-free optimized field metadata.

docs/guide/defining-documents.rst

@@ -172,11 +172,11 @@ arguments can be set on all fields:
         class Shirt(Document):
             size = StringField(max_length=3, choices=SIZE)
 
-:attr:`help_text` (Default: None)
-    Optional help text to output with the field -- used by form libraries
-
-:attr:`verbose_name` (Default: None)
-    Optional human-readable name for the field -- used by form libraries
+:attr:`**kwargs` (Optional)
+    You can supply additional metadata as arbitrary additional keyword
+    arguments.  You can not override existing attributes, however.  Common
+    choices include `help_text` and `verbose_name`, commonly used by form and
+    widget libraries.
 
 
 List fields

mongoengine/base/fields.py

@@ -41,8 +41,8 @@ class BaseField(object):
 
     def __init__(self, db_field=None, name=None, required=False, default=None,
                  unique=False, unique_with=None, primary_key=False,
-                 validation=None, choices=None, verbose_name=None,
-                 help_text=None, null=False, sparse=False, custom_data=None):
+                 validation=None, choices=None, null=False, sparse=False,
+                 **kwargs):
         """
         :param db_field: The database field to store this field in
             (defaults to the name of the field)
@@ -60,16 +60,15 @@ class BaseField(object):
             field.  Generally this is deprecated in favour of the
             `FIELD.validate` method
         :param choices: (optional) The valid choices
-        :param verbose_name: (optional)  The verbose name for the field.
-            Designed to be human readable and is often used when generating
-            model forms from the document model.
-        :param help_text: (optional) The help text for this field and is often
-            used when generating model forms from the document model.
         :param null: (optional) Is the field value can be null. If no and there is a default value
             then the default value is set
         :param sparse: (optional) `sparse=True` combined with `unique=True` and `required=False`
             means that uniqueness won't be enforced for `None` values
-        :param custom_data: (optional) Custom metadata for this field.
+        :param **kwargs: (optional) Arbitrary indirection-free metadata for
+            this field can be supplied as additional keyword arguments and
+            accessed as attributes of the field. Must not conflict with any
+            existing attributes. Common metadata includes `verbose_name` and
+            `help_text`.
         """
         self.db_field = (db_field or name) if not primary_key else '_id'
 
@@ -83,12 +82,19 @@ class BaseField(object):
         self.primary_key = primary_key
         self.validation = validation
         self.choices = choices
-        self.verbose_name = verbose_name
-        self.help_text = help_text
         self.null = null
         self.sparse = sparse
         self._owner_document = None
-        self.custom_data = custom_data
+        
+        # Detect and report conflicts between metadata and base properties.
+        conflicts = set(dir(self)) & set(kwargs)
+        if conflicts:
+            raise TypeError("%s already has attribute(s): %s" % (
+                self.__class__.__name__, ', '.join(conflicts) ))
+        
+        # Assign metadata to the instance
+        # This efficient method is available because no __slots__ are defined.
+        self.__dict__.update(kwargs)
 
         # Adjust the appropriate creation counter, and save our local copy.
         if self.db_field == '_id':