graphql-engine/server/src-lib/Hasura/Backends/MSSQL/Execute/Delete.hs
Tom Harding e0c0043e76 Upgrade Ormolu to 0.7.0.0
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/9284
GitOrigin-RevId: 2f2cf2ad01900a54e4bdb970205ac0ef313c7e00
2023-05-24 13:53:53 +00:00

102 lines
4.3 KiB
Haskell

{-# OPTIONS_HADDOCK ignore-exports #-}
-- | Responsible for translating and building an MSSQL execution plan for
-- delete mutations.
--
-- This module is used by "Hasura.Backends.MSSQL.Instances.Execute".
module Hasura.Backends.MSSQL.Execute.Delete
( executeDelete,
)
where
import Database.MSSQL.Transaction qualified as Tx
import Hasura.Backends.MSSQL.Connection
import Hasura.Backends.MSSQL.Execute.QueryTags
import Hasura.Backends.MSSQL.FromIr as TSQL
import Hasura.Backends.MSSQL.FromIr.Constants (tempTableNameDeleted)
import Hasura.Backends.MSSQL.FromIr.Delete qualified as TSQL
import Hasura.Backends.MSSQL.FromIr.MutationResponse
import Hasura.Backends.MSSQL.FromIr.SelectIntoTempTable qualified as TSQL
import Hasura.Backends.MSSQL.Plan
import Hasura.Backends.MSSQL.SQL.Error
import Hasura.Backends.MSSQL.ToQuery as TQ
import Hasura.Backends.MSSQL.Types.Internal as TSQL
import Hasura.Base.Error
import Hasura.EncJSON
import Hasura.GraphQL.Execute.Backend
import Hasura.Prelude
import Hasura.QueryTags (QueryTagsComment)
import Hasura.RQL.IR
import Hasura.RQL.Types.Backend
import Hasura.RQL.Types.BackendType
import Hasura.RQL.Types.Schema.Options qualified as Options
import Hasura.Session
-- | Executes a Delete IR AST and return results as JSON.
executeDelete ::
(MonadError QErr m, MonadReader QueryTagsComment m) =>
UserInfo ->
Options.StringifyNumbers ->
SourceConfig 'MSSQL ->
AnnDelG 'MSSQL Void (UnpreparedValue 'MSSQL) ->
m (OnBaseMonad (ExceptT QErr) EncJSON)
executeDelete userInfo stringifyNum sourceConfig deleteOperation = do
queryTags <- ask
preparedDelete <- traverse (prepareValueQuery $ _uiSession userInfo) deleteOperation
pure $ OnBaseMonad $ mssqlRunReadWrite (_mscExecCtx sourceConfig) (buildDeleteTx preparedDelete stringifyNum queryTags)
-- | Converts a Delete IR AST to a transaction of three delete sql statements.
--
-- A GraphQL delete mutation does two things:
--
-- 1. Deletes rows in a table according to some predicate
-- 2. (Potentially) returns the deleted rows (including relationships) as JSON
--
-- In order to complete these 2 things we need 3 SQL statements:
--
-- 1. @SELECT INTO <temp_table> WHERE <false>@ - creates a temporary table
-- with the same schema as the original table in which we'll store the deleted rows
-- from the table we are deleting
-- 2. @DELETE FROM with OUTPUT@ - deletes the rows from the table and inserts the
-- deleted rows to the temporary table from (1)
-- 3. @SELECT@ - constructs the @returning@ query from the temporary table, including
-- relationships with other tables.
buildDeleteTx ::
(MonadIO m) =>
AnnDel 'MSSQL ->
Options.StringifyNumbers ->
QueryTagsComment ->
Tx.TxET QErr m EncJSON
buildDeleteTx deleteOperation stringifyNum queryTags = do
let withAlias = "with_alias"
createInsertedTempTableQuery =
toQueryFlat
$ TQ.fromSelectIntoTempTable
$ TSQL.toSelectIntoTempTable tempTableNameDeleted (_adTable deleteOperation) (_adAllCols deleteOperation) RemoveConstraints
-- Create a temp table
Tx.unitQueryE defaultMSSQLTxErrorHandler (createInsertedTempTableQuery `withQueryTags` queryTags)
let deleteQuery = TQ.fromDelete <$> TSQL.fromDelete deleteOperation
deleteQueryValidated <- toQueryFlat . qwdQuery <$> runFromIrErrorOnCTEs deleteQuery
-- Execute DELETE statement
Tx.unitQueryE mutationMSSQLTxErrorHandler (deleteQueryValidated `withQueryTags` queryTags)
mutationOutputSelect <- qwdQuery <$> runFromIrUseCTEs (mkMutationOutputSelect stringifyNum withAlias $ _adOutput deleteOperation)
let withSelect =
emptySelect
{ selectProjections = [StarProjection],
selectFrom = Just $ FromTempTable $ Aliased tempTableNameDeleted "deleted_alias"
}
finalMutationOutputSelect = mutationOutputSelect {selectWith = Just $ With $ pure $ Aliased (CTESelect withSelect) withAlias}
mutationOutputSelectQuery = toQueryFlat $ TQ.fromSelect finalMutationOutputSelect
-- Execute SELECT query and fetch mutation response
result <- encJFromText <$> Tx.singleRowQueryE defaultMSSQLTxErrorHandler (mutationOutputSelectQuery `withQueryTags` queryTags)
-- delete the temporary table
let dropDeletedTempTableQuery = toQueryFlat $ dropTempTableQuery tempTableNameDeleted
Tx.unitQueryE defaultMSSQLTxErrorHandler (dropDeletedTempTableQuery `withQueryTags` queryTags)
-- return results
pure result