Re: [Sqlalchemy-tickets] [sqlalchemy] #2943: @validates on inherited subclasses

[sqlalchemy <mi...@zz...>]

#2943: @validates on inherited subclasses
---------------------------+-------------------------------
      Reporter:  zzzeek    |      Owner:  zzzeek
          Type:  defect    |     Status:  new
      Priority:  high      |  Milestone:  0.9.3
     Component:  orm       |   Severity:  major - 1-3 hours
    Resolution:            |   Keywords:
Progress State:  in queue  |
---------------------------+-------------------------------

Comment (by zzzeek):

 here's that....

 im a little concerned about setup performance here.

 {{{
 #!diff
 diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
 index 26f105b..7928310 100644
 --- a/lib/sqlalchemy/orm/mapper.py
 +++ b/lib/sqlalchemy/orm/mapper.py
 @@ -2603,6 +2603,7 @@ def validates(*names, **kw):
       argument "is_remove" which will be a boolean.

       .. versionadded:: 0.7.7
 +
      :param include_backrefs: defaults to ``True``; if ``False``, the
       validation function will not emit if the originator is an attribute
       event related via a backref.  This can be used for bi-directional
 @@ -2611,6 +2612,15 @@ def validates(*names, **kw):

       .. versionadded:: 0.9.0

 +    :param override: if ``True``, this validation function can be
 +     specified on a subclass which inherits the mapped attribute,
 +     where it will override any existing validators on the superclass.
 +     If not present, a ``@validates`` decorator on a subclass raises an
 +     error, as it currently takes no effect.
 +
 +     .. versionadded:: 0.9.3
 +
 +
      .. seealso::

        :ref:`simple_validators` - usage examples for :func:`.validates`
 @@ -2618,12 +2628,14 @@ def validates(*names, **kw):
      """
      include_removes = kw.pop('include_removes', False)
      include_backrefs = kw.pop('include_backrefs', True)
 +    override = kw.pop('override', False)

      def wrap(fn):
          fn.__sa_validators__ = names
          fn.__sa_validation_opts__ = {
                    "include_removes": include_removes,
 -                  "include_backrefs": include_backrefs
 +                  "include_backrefs": include_backrefs,
 +                  "override": override
                  }
          return fn
      return wrap
 diff --git a/lib/sqlalchemy/orm/strategies.py
 b/lib/sqlalchemy/orm/strategies.py
 index 2c18e81..95b449d 100644
 --- a/lib/sqlalchemy/orm/strategies.py
 +++ b/lib/sqlalchemy/orm/strategies.py
 @@ -38,26 +38,20 @@ def _register_attribute(strategy, mapper, useobject,

      attribute_ext = list(util.to_list(prop.extension, default=[]))

 -    listen_hooks = []
 +    pre_validate_hooks = []
 +    post_validate_hooks = []

      if useobject and prop.single_parent:
 -        listen_hooks.append(single_parent_validator)
 -
 -    if prop.key in prop.parent.validators:
 -        fn, opts = prop.parent.validators[prop.key]
 -        listen_hooks.append(
 -            lambda desc, prop: orm_util._validator_events(desc,
 -                                prop.key, fn, **opts)
 -            )
 +        pre_validate_hooks.append(single_parent_validator)

      if useobject:
 -        listen_hooks.append(unitofwork.track_cascade_events)
 +        post_validate_hooks.append(unitofwork.track_cascade_events)

      # need to assemble backref listeners
      # after the singleparentvalidator, mapper validator
      backref = kw.pop('backref', None)
      if backref:
 -        listen_hooks.append(
 +        post_validate_hooks.append(
              lambda desc, prop: attributes.backref_listeners(desc,
                                  backref,
                                  uselist)
 @@ -85,7 +79,21 @@ def _register_attribute(strategy, mapper, useobject,
                  **kw
                  )

 -            for hook in listen_hooks:
 +            for hook in pre_validate_hooks:
 +                hook(desc, prop)
 +
 +            for super_m in m.iterate_to_root():
 +                if prop.key in super_m.validators:
 +                    fn, opts = super_m.validators[prop.key]
 +                    if not opts["override"] and super_m is not mapper:
 +                        raise sa_exc.InvalidRequestError(
 +                                    "validator on inheriting class %s.%s
 won't "
 +                                    "run by default; please specify
 override=True" %
 +                                    (super_m.class_.__name__, prop.key))
 +                    orm_util._validator_events(desc, prop.key, fn,
 **opts)
 +                    break
 +
 +            for hook in post_validate_hooks:
                  hook(desc, prop)

  @properties.ColumnProperty.strategy_for(instrument=False, deferred=False)
 diff --git a/lib/sqlalchemy/orm/util.py b/lib/sqlalchemy/orm/util.py
 index dd85f2e..3a05b84 100644
 --- a/lib/sqlalchemy/orm/util.py
 +++ b/lib/sqlalchemy/orm/util.py
 @@ -70,7 +70,7 @@ class CascadeOptions(frozenset):
          )


 -def _validator_events(desc, key, validator, include_removes,
 include_backrefs):
 +def _validator_events(desc, key, validator, include_removes,
 include_backrefs, override):
      """Runs a validation method on an attribute value to be set or
 appended."""

      if not include_backrefs:
 }}}

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Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2943#comment:2>
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