sqlalchemy.sql.base.DedupeColumnCollection

class documentation

class DedupeColumnCollection(ColumnCollection):

A _expression.ColumnCollection that maintains deduplicating behavior.

This is useful by schema level objects such as _schema.Table and .PrimaryKeyConstraint. The collection includes more sophisticated mutator methods as well to suit schema objects which require mutable column collections.

New in version 1.4.

Method	`_populate_separate_keys`	populate from an iterator of (key, column)
Method	`add`	Add a column to this `_sql.ColumnCollection`.
Method	`extend`	Undocumented
Method	`remove`	Dictionary remove() is not implemented for `_sql.ColumnCollection`.
Method	`replace`	add the given column to this collection, removing unaliased versions of this column as well as existing columns with the same key.

Inherited from ColumnCollection:

Method	`as_immutable`	Return an "immutable" form of this `_sql.ColumnCollection`.
Method	`clear`	Dictionary clear() is not implemented for `_sql.ColumnCollection`.
Method	`compare`	Compare this `_expression.ColumnCollection` to another based on the names of the keys
Method	`contains_column`	Checks if a column object exists in this collection
Method	`corresponding_column`	No summary
Method	`get`	Get a `_sql.ColumnClause` or `_schema.Column` object based on a string key name from this `_expression.ColumnCollection`.
Method	`items`	No summary
Method	`keys`	Return a sequence of string key names for all columns in this collection.
Method	`update`	Dictionary update() is not implemented for `_sql.ColumnCollection`.
Method	`values`	Return a sequence of `_sql.ColumnClause` or `_schema.Column` objects for all columns in this collection.
Method	`__bool__`	Undocumented
Method	`__contains__`	Undocumented
Method	`__delitem__`	Undocumented
Method	`__eq__`	Undocumented
Method	`__getattr__`	Undocumented
Method	`__getitem__`	Undocumented
Method	`__getstate__`	Undocumented
Method	`__init__`	Undocumented
Method	`__iter__`	Undocumented
Method	`__len__`	Undocumented
Method	`__setattr__`	Undocumented
Method	`__setitem__`	Undocumented
Method	`__setstate__`	Undocumented
Method	`__str__`	Undocumented
Method	`_initial_populate`	Undocumented
Class Variable	`__hash__`	Undocumented
Class Variable	`__slots__`	Undocumented
Property	`_all_columns`	Undocumented

def _populate_separate_keys(self, iter_):

overrides sqlalchemy.sql.expression.ColumnCollection._populate_separate_keys

populate from an iterator of (key, column)

def add(self, column, key=None):

overrides sqlalchemy.sql.expression.ColumnCollection.add

Add a column to this _sql.ColumnCollection.

Note

This method is not normally used by user-facing code, as the _sql.ColumnCollection is usually part of an existing object such as a _schema.Table. To add a _schema.Column to an existing _schema.Table object, use the _schema.Table.append_column method.

def extend(self, iter_):

Undocumented

def remove(self, column):

overrides sqlalchemy.sql.expression.ColumnCollection.remove

Dictionary remove() is not implemented for _sql.ColumnCollection.

def replace(self, column):

add the given column to this collection, removing unaliased versions of this column as well as existing columns with the same key.

e.g.:

t = Table('sometable', metadata, Column('col1', Integer))
t.columns.replace(Column('col1', Integer, key='columnone'))

will remove the original 'col1' from the collection, and add the new column under the name 'columnname'.

Used by schema.Column to override columns during table reflection.