handle multiple pks in AdminModelConverter.converter()

* New helper-function `contrib.sqla.tools.has_multiple_pks(model)`
* The unique validator is only added to the primary key column in `converter()`, when the model does not have multiple primary keys.
* Removed option `form_excluded_pk_columns_from_unique_validation`
* documentation updated
* example updated

doc/db_sqla.rst

@@ -133,16 +133,15 @@ To be able to CRUD the ``Tyre`` class, two steps are necessary, when definig the
 
     class TyreAdmin(sqla.ModelView):
         form_columns = ['car', 'tyre_id', 'desc']
-        form_excluded_pk_columns_from_unique_validation = ('car_id', 'tyre_id')
 
 The ``form_columns`` needs to be explizit, as per default only one primary key is displayed. When, like in this
 example, one part of the key is a foreign key, do not include the foreign-key-columns here, but the
-coresponding relationship.
+corresponding relationship.
 
-Per default, all pimary-key-columns are validated for uniquenes. As describe in :doc:`api/mod_model`
-the ``form_excluded_pk_columns_from_unique_validation`` attribute can, and must, be used, to exclude *all*
-primary-key-columns from this check. Your database will tell you via ``Sqlalchemy``, if the operation
-was successfull or not. (Watch out for IntegrityErrors).
+When having multiple primary keys, **no** validation for uniqueness *prior* to saving of the object will be done. Saving
+a model that violates a unique-constraint leads to an Sqlalchemy-Integrity-Error. In this case, ``Flask-Admin`` displays
+a proper error message and you can change the data in the form. When the application has been started with ``debug=True``
+the ``werkzeug`` debugger catches the exception and displays the stacktrace.
 
 A standalone script with the Examples from above can be found in the examples directory.
 

examples/sqla/multiplepk.py

@@ -39,12 +39,11 @@ class Tyre(db.Model):
 
 class CarAdmin(sqla.ModelView):
     column_display_pk = True
+    form_columns = ['id', 'desc']
 
 class TyreAdmin(sqla.ModelView):
     column_display_pk = True
     form_columns = ['car', 'tyre_id', 'desc']
-    form_excluded_pk_columns_from_unique_validation = ('car_id', 'tyre_id')
-
 
 if __name__ == '__main__':
     # Create admin

flask_admin/contrib/sqla/form.py

@@ -12,7 +12,7 @@ from flask.ext.admin._compat import iteritems
 
 from .validators import Unique
 from .fields import QuerySelectField, QuerySelectMultipleField, InlineModelFormList
-from .tools import is_inherited_primary_key, get_column_for_current_model
+from .tools import is_inherited_primary_key, get_column_for_current_model, has_multiple_pks
 
 try:
     # Field has better input parsing capabilities.
@@ -166,8 +166,8 @@ class AdminModelConverter(ModelConverterBase):
                         if prop.key not in form_columns:
                             return None
 
-                        # PK can be explicitely excluded from uniquenes-validation
-                        if prop.key not in self.view.form_excluded_pk_columns_from_unique_validation:
+                        # Current Unique Validator does not work with multicolumns-pks
+                        if not has_multiple_pks(model):
                             kwargs['validators'].append(Unique(self.session,
                                                                model,
                                                                column))

flask_admin/contrib/sqla/tools.py

@@ -67,3 +67,11 @@ def get_column_for_current_model(prop):
     else:
         return candidates[0]
 
+
+def has_multiple_pks(model):
+    """Return True, if the model has more than one primary key
+    """
+    if not hasattr(model, '_sa_class_manager'):
+        raise TypeError('model must be a sqlalchemy mapped model')
+    pks = model._sa_class_manager.mapper.primary_key
+    return len(pks) > 1

flask_admin/contrib/sqla/view.py

@@ -259,9 +259,6 @@ class ModelView(BaseModelView):
         if self.form_choices is None:
             self.form_choices = {}
 
-        if self.form_excluded_pk_columns_from_unique_validation is None:
-            self.form_excluded_pk_columns_from_unique_validation = ()
-
         super(ModelView, self).__init__(model, name, category, endpoint, url)
 
         # Primary key

flask_admin/model/base.py

@@ -312,22 +312,6 @@ class BaseModelView(BaseView, ActionsMixin):
                 form_excluded_columns = ('last_name', 'email')
     """
 
-    form_excluded_pk_columns_from_unique_validation = None
-    """
-        Primary Key Columns, that should explicitely excluded from Validation for uniquenes.
-        Primary Keys are automatically checked for uniqueness *prior* to the database-save operation.
-        If your model consists of multiple primary keys, list them here, so the built-in validation
-        is disabled.
-
-        The constraints-check of the database will, of course, still prevent you from saving two identical
-        primary keys, regardless of how many columns are part of your primary key.
-
-        For example::
-
-            class MyModelView(BaseModelView):
-                form_excluded_pk_columns_from_unique_validation = ('id', 'secondid')
-    """
-
     form_overrides = None
     """
         Dictionary of form column overrides.