SQLAlchemy 0.4 Documentation - module sqlalchemy.orm.query

# SQLAlchemy 0.4 Documentation

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Version: 0.4.1 Last Updated: 11/18/07 17:50:18

### module sqlalchemy.orm.query

### class Query(object)

Encapsulates the object-fetching operations provided by Mappers.

def __init__(self, class_or_mapper, session=None, entity_name=None)

Construct a new `Query`.

def add_column(self, column, id=None)

add a SQL ColumnElement to the list of result columns to be returned.

This will have the effect of all result-returning methods returning a tuple of results, the first element being an instance of the primary class for this Query, and subsequent elements matching columns or entities which were specified via add_column or add_entity.

When adding columns to the result, its generally desireable to add limiting criterion to the query which can associate the primary entity of this Query along with the additional columns, if the column is based on a table or selectable that is not the primary mapped selectable. The Query selects from all tables with no joining criterion by default.

> column
>   a string column name or sql.ColumnElement to be added to the results.

def add_entity(self, entity, alias=None, id=None)

add a mapped entity to the list of result columns to be returned.

This will have the effect of all result-returning methods returning a tuple of results, the first element being an instance of the primary class for this Query, and subsequent elements matching columns or entities which were specified via add_column or add_entity.

When adding entities to the result, its generally desireable to add limiting criterion to the query which can associate the primary entity of this Query along with the additional entities. The Query selects from all tables with no joining criterion by default.

> entity
>   a class or mapper which will be added to the results.
> alias
>   a sqlalchemy.sql.Alias object which will be used to select rows. this will match the usage of the given Alias in filter(), order_by(), etc. expressions
> id
>   a string ID matching that given to query.join() or query.outerjoin(); rows will be selected from the aliased join created via those methods.

def all(self)

Return the results represented by this `Query` as a list.

This results in an execution of the underlying query.

def apply_avg(self, col)

apply the SQL `avg()` function against the given column to the query and return the newly resulting `Query`.

def apply_max(self, col)

apply the SQL `max()` function against the given column to the query and return the newly resulting `Query`.

def apply_min(self, col)

apply the SQL `min()` function against the given column to the query and return the newly resulting `Query`.

def apply_sum(self, col)

apply the SQL `sum()` function against the given column to the query and return the newly resulting `Query`.

def autoflush(self, setting)
def avg(self, col)

Execute the SQL `avg()` function against the given column.

def compile(self)

compiles and returns a SQL statement based on the criterion and conditions within this Query.

def count(self, whereclause=None, params=None, **kwargs)

Apply this query's criterion to a SELECT COUNT statement.

the whereclause, params and **kwargs arguments are deprecated. use filter() and other generative methods to establish modifiers.

def count_by(*args, **kwargs)

DEPRECATED. use query.filter_by(**params).count()

def distinct(self)

Apply a `DISTINCT` to the query and return the newly resulting `Query`.

def execute(*args, **kwargs)

DEPRECATED. use query.from_statement().all()

def filter(self, criterion)

apply the given filtering criterion to the query and return the newly resulting `Query`

the criterion is any sql.ClauseElement applicable to the WHERE clause of a select.

def filter_by(self, **kwargs)

apply the given filtering criterion to the query and return the newly resulting `Query`.

def first(self)

Return the first result of this `Query` or None if the result doesn't contain any row.

This results in an execution of the underlying query.

def from_statement(self, statement)
def get(self, ident, **kwargs)

Return an instance of the object based on the given identifier, or None if not found.

The ident argument is a scalar or tuple of primary key column values in the order of the table def's primary key columns.

def get_by(*args, **kwargs)

DEPRECATED. use query.filter_by(**params).first()

def group_by(self, criterion)

apply one or more GROUP BY criterion to the query and return the newly resulting `Query`

def having(self, criterion)

apply a HAVING criterion to the quer and return the newly resulting `Query`.

def instances(self, cursor, *mappers_or_columns, **kwargs)

Return a list of mapped instances corresponding to the rows in a given cursor (i.e. `ResultProxy`).

The *mappers_or_columns and **kwargs arguments are deprecated. To add instances or columns to the results, use add_entity() and add_column().

def join(self, prop, id=None, aliased=False, from_joinpoint=False)

create a join of this `Query` object's criterion to a relationship and return the newly resulting `Query`.

'prop' may be a string property name or a list of string property names.

def join_by(*args, **kwargs)

DEPRECATED. use join() to construct joins based on attribute names.

def join_to(*args, **kwargs)

DEPRECATED. use join() to create joins based on property names.

def join_via(*args, **kwargs)

DEPRECATED. use join() to create joins based on property names.

def limit(self, limit)

Apply a `LIMIT` to the query and return the newly resulting `Query`.

def list(*args, **kwargs)

DEPRECATED. use all()

def load(self, ident, raiseerr=True, **kwargs)

Return an instance of the object based on the given identifier.

If not found, raises an exception. The method will remove all pending changes to the object already existing in the Session. The ident argument is a scalar or tuple of primary key column values in the order of the table def's primary key columns.

def max(self, col)

Execute the SQL `max()` function against the given column.

def min(self, col)

Execute the SQL `min()` function against the given column.

def offset(self, offset)

Apply an `OFFSET` to the query and return the newly resulting `Query`.

def one(self)

Return the first result of this `Query`, raising an exception if more than one row exists.

This results in an execution of the underlying query.

def options(self, *args)

Return a new Query object, applying the given list of MapperOptions.

def order_by(self, criterion)

apply one or more ORDER BY criterion to the query and return the newly resulting `Query`

def outerjoin(self, prop, id=None, aliased=False, from_joinpoint=False)

create a left outer join of this `Query` object's criterion to a relationship and return the newly resulting `Query`.

'prop' may be a string property name or a list of string property names.

def params(self, *args, **kwargs)

add values for bind parameters which may have been specified in filter().

parameters may be specified using **kwargs, or optionally a single dictionary as the first positional argument. The reason for both is that **kwargs is convenient, however some parameter dictionaries contain unicode keys in which case **kwargs cannot be used.

def populate_existing(self)

return a Query that will refresh all instances loaded.

this includes all entities accessed from the database, including secondary entities, eagerly-loaded collection items.

All changes present on entities which are already present in the session will be reset and the entities will all be marked "clean".

This is essentially the en-masse version of load().

primary_key_columns = property()
def query_from_parent(cls, instance, property, **kwargs)

return a newly constructed Query object, with criterion corresponding to a relationship to the given parent instance.

> instance
>   a persistent or detached instance which is related to class represented by this query.
> property
>   string name of the property which relates this query's class to the instance.
> **kwargs
>   all extra keyword arguments are propigated to the constructor of Query.

def reset_joinpoint(self)

return a new Query reset the 'joinpoint' of this Query reset back to the starting mapper. Subsequent generative calls will be constructed from the new joinpoint.

Note that each call to join() or outerjoin() also starts from the root.

def scalar(*args, **kwargs)

DEPRECATED. use first()

def select(*args, **kwargs)

DEPRECATED. use query.filter(whereclause).all(), or query.from_statement(statement).all()

def select_by(*args, **kwargs)

DEPRECATED. use use query.filter_by(**params).all().

def select_from(self, from_obj)

Set the from_obj parameter of the query and return the newly resulting `Query`.

from_obj is a list of one or more tables.

def select_statement(*args, **kwargs)

DEPRECATED. Use query.from_statement(statement)

def select_text(*args, **kwargs)

DEPRECATED. Use query.from_statement(statement)

def select_whereclause(*args, **kwargs)

DEPRECATED. use query.filter(whereclause).all()

def selectfirst(*args, **kwargs)

DEPRECATED. use query.filter(whereclause).first()

def selectfirst_by(*args, **kwargs)

DEPRECATED. Use query.filter_by(**kwargs).first()

def selectone(*args, **kwargs)

DEPRECATED. use query.filter(whereclause).one()

def selectone_by(*args, **kwargs)

DEPRECATED. Use query.filter_by(**kwargs).one()

session = property()
def sum(self, col)

Execute the SQL `sum()` function against the given column.

table = property()
def with_lockmode(self, mode)

Return a new Query object with the specified locking mode.

def with_parent(self, instance, property=None)

add a join criterion corresponding to a relationship to the given parent instance.

> instance
>   a persistent or detached instance which is related to class represented by this query.
> property
>   string name of the property which relates this query's class to the instance. if None, the method will attempt to find a suitable property.

currently, this method only works with immediate parent relationships, but in the future may be enhanced to work across a chain of parent mappers.

def __getitem__(self, item)
def __iter__(self)
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