graphql-engine-1.0.0: GraphQL API over Postgres
Safe HaskellNone
LanguageHaskell2010

Hasura.Backends.MSSQL.FromIr.MutationResponse

Description

This module defines translation functions that yield the results of mutation requests that return the data of rows that were affected.

Synopsis

Documentation

mkMutationOutputSelect :: StringifyNumbers -> Text -> MutationOutputG 'MSSQL Void Expression -> FromIr Select Source #

Generate a SQL SELECT statement which outputs the mutation response

For multi row inserts:

SELECT (SELECT COUNT(*) FROM [with_alias]) AS [affected_rows], (select_from_returning) AS [returning] FOR JSON PATH, INCLUDE_NULL_VALUES, WITHOUT_ARRAY_WRAPPER

For single row insert: the selection set is translated to SQL query using @fromSelect

selectMutationOutputAndCheckCondition :: Text -> Select -> Expression -> Select Source #

Generate a SQL SELECT statement which outputs both mutation response and check constraint result.

A check constraint applies to the data that has been changed, while permissions filter the data that is made available.

This function applies to insert and update mutations.

The check constraint boolean expression is evaluated on mutated rows in a CASE expression so that the int value "0" is returned when check constraint is true otherwise the int value "1" is returned. We use SUM aggregation on the returned value and if check constraint on any row is not met, the summed value will not equal to "0" (always > 1).

  <check_constraint_select> :=
    SELECT SUM([check_sub_query].[check_evaluation])
    FROM
      ( SELECT
          (CASE WHEN <check_boolean_expression> THEN 0 ELSE 1 END) AS [check_evaluation]
        FROM
          [with_alias]
      ) AS [check_sub_query]

  <mutation_output_select> :=
    SELECT
      (SELECT COUNT(*) FROM [with_alias]) AS [affected_rows],
      (select_from_returning) AS [returning]
    FOR JSON PATH, INCLUDE_NULL_VALUES, WITHOUT_ARRAY_WRAPPER

  SELECT
    (<mutation_output_select>) AS [mutation_response],
    (<check_constraint_select>) AS [check_constraint_select]