Class Col

Declaration

Methods

• ▶ def __init__(self, alias, target, output_field=None) override

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  This method overrides django.db.models.expressions.BaseExpression.__init__.

• ▷ def __repr__(self)

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• ▶ def as_sql(self, compiler, connection) override

  inherited doc Responsible for returning a (sql, [params]) tuple to be included in the current query.

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  This method overrides django.db.models.expressions.BaseExpression.as_sql.

  Different backends can provide their own implementation, by
  providing an `as_{vendor}` method and patching the Expression:
  
  ```
  def override_as_sql(self, compiler, connection):
      # custom logic
      return super().as_sql(compiler, connection)
  setattr(Expression, 'as_' + connection.vendor, override_as_sql)
  ```
  
  Arguments:
   * compiler: the query compiler responsible for generating the query.
     Must have a compile method, returning a (sql, [params]) tuple.
     Calling compiler(value) will return a quoted `value`.
  
   * connection: the database connection used for the current query.
  
  Return: (sql, params)
    Where `sql` is a string containing ordered sql parameters to be
    replaced with the elements of the list `params`.

• ▶ def get_db_converters(self, connection) override

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  This method overrides django.db.models.expressions.BaseExpression.get_db_converters.

• ▶ def get_group_by_cols(self, alias=None) override

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  This method overrides django.db.models.expressions.BaseExpression.get_group_by_cols.

• ▶ def relabeled_clone(self, relabels) override

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  This method overrides django.db.models.expressions.BaseExpression.relabeled_clone.

Inherited methods

• Methods inherited from django.db.models.expressions.BaseExpression:
  __eq__, __getstate__, __hash__, asc, conditional, contains_aggregate, contains_column_references, contains_over_clause, convert_value, copy, desc, field, flatten, get_lookup, get_source_expressions, get_source_fields, get_transform, identity, output_field, resolve_expression, reverse_ordering, select_format, set_source_expressions
• Methods inherited from django.db.models.expressions.Combinable:
  __add__, __and__, __mod__, __mul__, __neg__, __or__, __pow__, __radd__, __rand__, __rmod__, __rmul__, __ror__, __rpow__, __rsub__, __rtruediv__, __sub__, __truediv__, bitand, bitleftshift, bitor, bitrightshift, bitxor

Reexports

• Imported in django.db.backends.sqlite3.operations.
• Imported in django.db.models.sql.query.

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