diff options
Diffstat (limited to 'lib/sqlalchemy/ext/hybrid.py')
| -rw-r--r-- | lib/sqlalchemy/ext/hybrid.py | 31 |
1 files changed, 18 insertions, 13 deletions
diff --git a/lib/sqlalchemy/ext/hybrid.py b/lib/sqlalchemy/ext/hybrid.py index 7c523edbd..9f73b5d31 100644 --- a/lib/sqlalchemy/ext/hybrid.py +++ b/lib/sqlalchemy/ext/hybrid.py @@ -75,7 +75,8 @@ returns a new SQL expression:: FROM interval WHERE interval."end" - interval.start > :param_1 -ORM methods such as :meth:`~.Query.filter_by` generally use ``getattr()`` to +ORM methods such as :meth:`_query.Query.filter_by` +generally use ``getattr()`` to locate attributes, so can also be used with hybrid attributes:: >>> print(Session().query(Interval).filter_by(length=5)) @@ -213,10 +214,10 @@ Allowing Bulk ORM Update ------------------------ A hybrid can define a custom "UPDATE" handler for when using the -:meth:`.Query.update` method, allowing the hybrid to be used in the +:meth:`_query.Query.update` method, allowing the hybrid to be used in the SET clause of the update. -Normally, when using a hybrid with :meth:`.Query.update`, the SQL +Normally, when using a hybrid with :meth:`_query.Query.update`, the SQL expression is used as the column that's the target of the SET. If our ``Interval`` class had a hybrid ``start_point`` that linked to ``Interval.start``, this could be substituted directly:: @@ -225,7 +226,7 @@ expression is used as the column that's the target of the SET. If our However, when using a composite hybrid like ``Interval.length``, this hybrid represents more than one column. We can set up a handler that will -accommodate a value passed to :meth:`.Query.update` which can affect +accommodate a value passed to :meth:`_query.Query.update` which can affect this, using the :meth:`.hybrid_property.update_expression` decorator. A handler that works similarly to our setter would be:: @@ -628,9 +629,11 @@ measurement, currencies and encrypted passwords. Building Transformers ---------------------- -A *transformer* is an object which can receive a :class:`.Query` object and -return a new one. The :class:`.Query` object includes a method -:meth:`.with_transformation` that returns a new :class:`.Query` transformed by +A *transformer* is an object which can receive a :class:`_query.Query` +object and +return a new one. The :class:`_query.Query` object includes a method +:meth:`.with_transformation` that returns a new :class:`_query.Query` +transformed by the given function. We can combine this with the :class:`.Comparator` class to produce one type @@ -665,10 +668,11 @@ simple:: return self.parent.parent For the expression, things are not so clear. We'd need to construct a -:class:`.Query` where we :meth:`~.Query.join` twice along ``Node.parent`` to +:class:`_query.Query` where we :meth:`_query.Query.join` twice along ``Node. +parent`` to get to the ``grandparent``. We can instead return a transforming callable that we'll combine with the :class:`.Comparator` class to receive any -:class:`.Query` object, and return a new one that's joined to the +:class:`_query.Query` object, and return a new one that's joined to the ``Node.parent`` attribute and filtered based on the given criterion:: from sqlalchemy.ext.hybrid import Comparator @@ -704,9 +708,10 @@ transforming callable, which then runs the given comparison operation in a particular context. Such as, in the example above, the ``operate`` method is called, given the :attr:`.Operators.eq` callable as well as the right side of the comparison ``Node(id=5)``. A function ``transform`` is then returned which -will transform a :class:`.Query` first to join to ``Node.parent``, then to +will transform a :class:`_query.Query` first to join to ``Node.parent``, +then to compare ``parent_alias`` using :attr:`.Operators.eq` against the left and right -sides, passing into :class:`.Query.filter`: +sides, passing into :class:`_query.Query.filter`: .. sourcecode:: pycon+sql @@ -783,7 +788,7 @@ HYBRID_METHOD = util.symbol("HYBRID_METHOD") .. seealso:: - :attr:`.Mapper.all_orm_attributes` + :attr:`_orm.Mapper.all_orm_attributes` """ @@ -796,7 +801,7 @@ HYBRID_PROPERTY = util.symbol("HYBRID_PROPERTY") .. seealso:: - :attr:`.Mapper.all_orm_attributes` + :attr:`_orm.Mapper.all_orm_attributes` """ |