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## Description We go through the module `Hasura.Backends.MSSQL.FromIr` and split it into separate self-contained units, which we document. Note that this PR has a slightly opinionated follow-up PR #3909 . ### Related Issues Fix #3666 ### Solution and Design The module `FromIr` has given rise to: * `FromIr.Expression` * `FromIr.Query` * `FromIr.Delete` * `FromIr.Insert` * `FromIr.Update` * `FromIr.SelectIntoTempTable` And `Execute.MutationResponse` has become `FromIr.MutationResponse` (after some slight adaptation of types). PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3908 GitOrigin-RevId: 364acf1bcdf74f2e19464c31cdded12bd8e9aa59
102 lines
4.6 KiB
Haskell
102 lines
4.6 KiB
Haskell
{-# OPTIONS_HADDOCK ignore-exports #-}
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-- | Responsible for translating and building an MSSQL execution plan for
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-- update mutations.
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--
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-- This module is used by "Hasura.Backends.MSSQL.Instances.Execute".
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module Hasura.Backends.MSSQL.Execute.Update
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( executeUpdate,
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)
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where
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import Database.MSSQL.Transaction qualified as Tx
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import Hasura.Backends.MSSQL.Connection
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import Hasura.Backends.MSSQL.FromIr as TSQL
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import Hasura.Backends.MSSQL.FromIr.Constants (tempTableNameUpdated)
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import Hasura.Backends.MSSQL.FromIr.Expression (fromGBoolExp)
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import Hasura.Backends.MSSQL.FromIr.MutationResponse
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import Hasura.Backends.MSSQL.FromIr.SelectIntoTempTable qualified as TSQL
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import Hasura.Backends.MSSQL.FromIr.Update qualified as TSQL
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import Hasura.Backends.MSSQL.Plan
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import Hasura.Backends.MSSQL.SQL.Error
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import Hasura.Backends.MSSQL.ToQuery as TQ
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import Hasura.Backends.MSSQL.Types.Internal as TSQL
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import Hasura.Backends.MSSQL.Types.Update
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import Hasura.Base.Error
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import Hasura.EncJSON
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import Hasura.GraphQL.Parser
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import Hasura.Prelude
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import Hasura.RQL.IR
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import Hasura.RQL.IR qualified as IR
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import Hasura.RQL.Types
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import Hasura.Session
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-- | Executes an Update IR AST and return results as JSON.
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executeUpdate ::
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MonadError QErr m =>
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UserInfo ->
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StringifyNumbers ->
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SourceConfig 'MSSQL ->
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AnnotatedUpdateG 'MSSQL Void (UnpreparedValue 'MSSQL) ->
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m (ExceptT QErr IO EncJSON)
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executeUpdate userInfo stringifyNum sourceConfig updateOperation = do
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let mssqlExecCtx = (_mscExecCtx sourceConfig)
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preparedUpdate <- traverse (prepareValueQuery $ _uiSession userInfo) updateOperation
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if null $ updateOperations . _auBackend $ updateOperation
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then pure $ pure $ IR.buildEmptyMutResp $ _auOutput preparedUpdate
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else pure $ (mssqlRunReadWrite mssqlExecCtx) (buildUpdateTx preparedUpdate stringifyNum)
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-- | Converts an Update IR AST to a transaction of three update sql statements.
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--
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-- A GraphQL update mutation does two things:
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--
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-- 1. Update rows in a table according to some predicate
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-- 2. (Potentially) returns the updated rows (including relationships) as JSON
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--
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-- In order to complete these 2 things we need 3 SQL statements:
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--
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-- 1. @SELECT INTO <temp_table> WHERE <false>@ - creates a temporary table
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-- with the same schema as the original table in which we'll store the updated rows
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-- from the table we are deleting
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-- 2. @UPDATE SET FROM with OUTPUT@ - updates the rows from the table and inserts the
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-- updated rows to the temporary table from (1)
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-- 3. @SELECT@ - constructs the @returning@ query from the temporary table, including
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-- relationships with other tables.
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buildUpdateTx ::
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AnnotatedUpdate 'MSSQL ->
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StringifyNumbers ->
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Tx.TxET QErr IO EncJSON
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buildUpdateTx updateOperation stringifyNum = do
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let withAlias = "with_alias"
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createInsertedTempTableQuery =
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toQueryFlat $
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TQ.fromSelectIntoTempTable $
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TSQL.toSelectIntoTempTable tempTableNameUpdated (_auTable updateOperation) (_auAllCols updateOperation) RemoveConstraints
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-- Create a temp table
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Tx.unitQueryE defaultMSSQLTxErrorHandler createInsertedTempTableQuery
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let updateQuery = TQ.fromUpdate <$> TSQL.fromUpdate updateOperation
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updateQueryValidated <- toQueryFlat <$> runFromIr updateQuery
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-- Execute UPDATE statement
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Tx.unitQueryE mutationMSSQLTxErrorHandler updateQueryValidated
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mutationOutputSelect <- runFromIr $ mkMutationOutputSelect stringifyNum withAlias $ _auOutput updateOperation
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let checkCondition = _auCheck updateOperation
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-- The check constraint is translated to boolean expression
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checkBoolExp <- runFromIr $ runReaderT (fromGBoolExp checkCondition) (EntityAlias withAlias)
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let withSelect =
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emptySelect
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{ selectProjections = [StarProjection],
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selectFrom = Just $ FromTempTable $ Aliased tempTableNameUpdated "updated_alias"
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}
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mutationOutputCheckConstraintSelect = selectMutationOutputAndCheckCondition withAlias mutationOutputSelect checkBoolExp
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finalSelect = mutationOutputCheckConstraintSelect {selectWith = Just $ With $ pure $ Aliased withSelect withAlias}
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-- Execute SELECT query to fetch mutation response and check constraint result
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(responseText, checkConditionInt) <- Tx.singleRowQueryE defaultMSSQLTxErrorHandler (toQueryFlat $ TQ.fromSelect finalSelect)
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-- Drop the temp table
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Tx.unitQueryE defaultMSSQLTxErrorHandler $ toQueryFlat $ dropTempTableQuery tempTableNameUpdated
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-- Raise an exception if the check condition is not met
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unless (checkConditionInt == (0 :: Int)) $
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throw400 PermissionError "check constraint of an update permission has failed"
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pure $ encJFromText responseText
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