diff options
Diffstat (limited to 'lib/sqlalchemy/orm/query.py')
| -rw-r--r-- | lib/sqlalchemy/orm/query.py | 174 |
1 files changed, 168 insertions, 6 deletions
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py index d64575aec..c3e5aa10d 100644 --- a/lib/sqlalchemy/orm/query.py +++ b/lib/sqlalchemy/orm/query.py @@ -35,6 +35,8 @@ from ..sql import ( util as sql_util, expression, visitors ) +from ..sql.base import ColumnCollection +from ..sql import operators from . import properties __all__ = ['Query', 'QueryContext', 'aliased'] @@ -2890,6 +2892,8 @@ class _QueryEntity(object): if not isinstance(entity, util.string_types) and \ _is_mapped_class(entity): cls = _MapperEntity + elif isinstance(entity, Bundle): + cls = _BundleEntity else: cls = _ColumnEntity return object.__new__(cls) @@ -3089,6 +3093,163 @@ class _MapperEntity(_QueryEntity): def __str__(self): return str(self.mapper) +@inspection._self_inspects +class Bundle(object): + """A grouping of SQL expressions that are returned by a :class:`.Query` + under one namespace. + + The :class:`.Bundle` essentially allows nesting of the tuple-based + results returned by a column-oriented :class:`.Query` object. It also + is extensible via simple subclassing, where the primary capability + to override is that of how the set of expressions should be returned, + allowing post-processing as well as custom return types, without + involving ORM identity-mapped classes. + + .. versionadded:: 0.9.0 + + .. seealso:: + + :ref:`bundles` + + """ + + def __init__(self, name, *exprs): + """Construct a new :class:`.Bundle`. + + e.g.:: + + bn = Bundle("mybundle", MyClass.x, MyClass.y) + + for row in session.query(bn).filter(bn.c.x == 5).filter(bn.c.y == 4): + print(row.mybundle.x, row.mybundle.y) + + """ + self.name = self._label = name + self.exprs = exprs + self.c = self.columns = ColumnCollection() + self.columns.update((getattr(col, "key", col._label), col) + for col in exprs) + + columns = None + """A namespace of SQL expressions referred to by this :class:`.Bundle`. + + e.g.:: + + bn = Bundle("mybundle", MyClass.x, MyClass.y) + + q = sess.query(bn).filter(bn.c.x == 5) + + Nesting of bundles is also supported:: + + b1 = Bundle("b1", + Bundle('b2', MyClass.a, MyClass.b), + Bundle('b3', MyClass.x, MyClass.y) + ) + + q = sess.query(b1).filter(b1.c.b2.c.a == 5).filter(b1.c.b3.c.y == 9) + + .. seealso:: + + :attr:`.Bundle.c` + + """ + + c = None + """An alias for :attr:`.Bundle.columns`.""" + + def _clone(self): + cloned = self.__class__.__new__(self.__class__) + cloned.__dict__.update(self.__dict__) + return cloned + + def __clause_element__(self): + return expression.ClauseList(group=False, *self.c) + + @property + def clauses(self): + return self.__clause_element__().clauses + + def label(self, name): + """Provide a copy of this :class:`.Bundle` passing a new label.""" + + cloned = self._clone() + cloned.name = name + return cloned + + def create_row_processor(self, query, procs, labels): + """Produce the "row processing" function for this :class:`.Bundle`. + + May be overridden by subclasses. + + .. seealso:: + + :ref:`bundles` - includes an example of subclassing. + + """ + def proc(row, result): + return util.KeyedTuple([proc(row, None) for proc in procs], labels) + return proc + + +class _BundleEntity(_QueryEntity): + def __init__(self, query, bundle, setup_entities=True): + query._entities.append(self) + self.bundle = self.entity_zero = bundle + self.type = type(bundle) + self._label_name = bundle.name + self._entities = [] + + if setup_entities: + for expr in bundle.exprs: + if isinstance(expr, Bundle): + _BundleEntity(self, expr) + else: + _ColumnEntity(self, expr, namespace=self) + + self.entities = () + + self.filter_fn = lambda item: item + + def corresponds_to(self, entity): + # TODO: this seems to have no effect for + # _ColumnEntity either + return False + + @property + def entity_zero_or_selectable(self): + for ent in self._entities: + ezero = ent.entity_zero_or_selectable + if ezero is not None: + return ezero + else: + return None + + def adapt_to_selectable(self, query, sel): + c = _BundleEntity(query, self.bundle, setup_entities=False) + #c._label_name = self._label_name + #c.entity_zero = self.entity_zero + #c.entities = self.entities + + for ent in self._entities: + ent.adapt_to_selectable(c, sel) + + def setup_entity(self, ext_info, aliased_adapter): + for ent in self._entities: + ent.setup_entity(ext_info, aliased_adapter) + + def setup_context(self, query, context): + for ent in self._entities: + ent.setup_context(query, context) + + def row_processor(self, query, context, custom_rows): + procs, labels = zip( + *[ent.row_processor(query, context, custom_rows) + for ent in self._entities] + ) + + proc = self.bundle.create_row_processor(query, procs, labels) + + return proc, self._label_name class _ColumnEntity(_QueryEntity): """Column/expression based entity.""" @@ -3105,7 +3266,7 @@ class _ColumnEntity(_QueryEntity): interfaces.PropComparator )): self._label_name = column.key - column = column.__clause_element__() + column = column._query_clause_element() else: self._label_name = getattr(column, 'key', None) @@ -3118,6 +3279,9 @@ class _ColumnEntity(_QueryEntity): if c is not column: return + elif isinstance(column, Bundle): + _BundleEntity(query, column) + return if not isinstance(column, sql.ColumnElement): raise sa_exc.InvalidRequestError( @@ -3125,7 +3289,7 @@ class _ColumnEntity(_QueryEntity): "expected - got '%r'" % (column, ) ) - type_ = column.type + self.type = type_ = column.type if type_.hashable: self.filter_fn = lambda item: item else: @@ -3177,10 +3341,6 @@ class _ColumnEntity(_QueryEntity): else: return None - @property - def type(self): - return self.column.type - def adapt_to_selectable(self, query, sel): c = _ColumnEntity(query, sel.corresponding_column(self.column)) c._label_name = self._label_name @@ -3193,6 +3353,8 @@ class _ColumnEntity(_QueryEntity): self.froms.add(ext_info.selectable) def corresponds_to(self, entity): + # TODO: just returning False here, + # no tests fail if self.entity_zero is None: return False elif _is_aliased_class(entity): |