django.db.models.expressions.TemporalSubtraction

class documentation

class TemporalSubtraction(CombinedExpression):

Undocumented

Method	`__init__`	Undocumented
Method	`as_sql`	Responsible for returning a (sql, [params]) tuple to be included in the current query.
Class Variable	`output_field`	Return the output type of this expressions.

Method	`__repr__`	Undocumented
Method	`__str__`	Undocumented
Method	`_resolve_output_field`	Attempt to infer the output type of the expression. If the output fields of all source fields match then, simply infer the same type here. This isn't always correct, but it makes sense most of the time.
Method	`get_source_expressions`	Undocumented
Method	`resolve_expression`	Provide the chance to do any preprocessing or validation before being added to the query.
Method	`set_source_expressions`	Undocumented
Instance Variable	`connector`	Undocumented
Instance Variable	`lhs`	Undocumented
Instance Variable	`rhs`	Undocumented

Method as_sqlite Undocumented

Static Method	`_convert_value_noop`	Undocumented
Method	`__getstate__`	Undocumented
Method	`_parse_expressions`	Undocumented
Method	`asc`	Undocumented
Method	`copy`	Undocumented
Method	`desc`	Undocumented
Method	`flatten`	Recursively yield this expression and all subexpressions, in depth-first order.
Method	`get_db_converters`	Undocumented
Method	`get_group_by_cols`	Undocumented
Method	`get_lookup`	Undocumented
Method	`get_source_fields`	Return the underlying field types used by this aggregate.
Method	`get_transform`	Undocumented
Method	`relabeled_clone`	Undocumented
Method	`reverse_ordering`	Undocumented
Method	`select_format`	Custom format for select clauses. For example, EXISTS expressions need to be wrapped in CASE WHEN on Oracle.
Class Variable	`_output_field_resolved_to_none`	Undocumented
Class Variable	`filterable`	Undocumented
Class Variable	`is_summary`	Undocumented
Class Variable	`window_compatible`	Undocumented
Property	`_output_field_or_none`	Return the output field of this expression, or None if _resolve_output_field() didn't return an output type.
Property	`conditional`	Undocumented
Property	`contains_aggregate`	Undocumented
Property	`contains_column_references`	Undocumented
Property	`contains_over_clause`	Undocumented
Property	`convert_value`	Expressions provide their own converters because users have the option of manually specifying the output_field which may be a different type from the one the database returns.
Property	`field`	Undocumented

def __init__(self, lhs, rhs):

overrides django.db.models.expressions.CombinedExpression.__init__

Undocumented

def as_sql(self, compiler, connection):

overrides django.db.models.expressions.CombinedExpression.as_sql

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

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.

output_field =

overrides django.db.models.expressions.BaseExpression.output_field

Return the output type of this expressions.