diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/sqlalchemy/orm/query.py | 36 |
1 files changed, 25 insertions, 11 deletions
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py index fe7595b9d..9eec1bc0e 100644 --- a/lib/sqlalchemy/orm/query.py +++ b/lib/sqlalchemy/orm/query.py @@ -119,8 +119,9 @@ class Query(object): return instance def get_by(self, *args, **params): - """Return a single object instance based on the given - key/value criterion. + """Like ``select_by()``, but only return the first + as a scalar, or None if no object found. + Synonymous with ``selectfirst_by()``. The criterion is constructed in the same way as the ``select_by()`` method. @@ -213,9 +214,9 @@ class Query(object): return clause def selectfirst_by(self, *args, **params): - """Like ``select_by()``, but only return the first result by - itself, or None if no objects returned. Synonymous with - ``get_by()``. + """Like ``select_by()``, but only return the first + as a scalar, or None if no object found. + Synonymous with ``get_by()``. The criterion is constructed in the same way as the ``select_by()`` method. @@ -250,8 +251,12 @@ class Query(object): return self.count(self.join_by(*args, **params)) def selectfirst(self, arg=None, **kwargs): - """Like ``select()``, but only return the first result by - itself, or None if no objects returned. + """Query for a single instance using the given criterion. + + Arguments are the same as ``select()``. In the case that + the given criterion represents ``WHERE`` criterion only, + LIMIT 1 is applied to the fully generated statement. + """ if isinstance(arg, sql.FromClause) and arg.supports_execution(): @@ -265,11 +270,20 @@ class Query(object): return None def selectone(self, arg=None, **kwargs): - """Like ``selectfirst()``, but throw an error if not exactly - one result was returned. - """ + """Query for a single instance using the given criterion. + + Unlike ``selectfirst``, this method asserts that only one + row exists. In the case that the given criterion represents + ``WHERE`` criterion only, LIMIT 2 is applied to the fully + generated statement. - ret = list(self.select(arg, **kwargs)[0:2]) + """ + + if isinstance(arg, sql.FromClause) and arg.supports_execution(): + ret = self.select_statement(arg, **kwargs) + else: + kwargs['limit'] = 2 + ret = self.select_whereclause(whereclause=arg, **kwargs) if len(ret) == 1: return ret[0] elif len(ret) == 0: |