graphql-engine/server/src-lib/Hasura/GraphQL/Execute/Mutation.hs
Vamshi Surabhi e8e4f30dd6 server: support remote relationships on SQL Server and BigQuery (#1497)
Remote relationships are now supported on SQL Server and BigQuery. The major change though is the re-architecture of remote join execution logic. Prior to this PR, each backend is responsible for processing the remote relationships that are part of their AST.

This is not ideal as there is nothing specific about a remote join's execution that ties it to a backend. The only backend specific part is whether or not the specification of the remote relationship is valid (i.e, we'll need to validate whether the scalars are compatible).

The approach now changes to this:

1. Before delegating the AST to the backend, we traverse the AST, collect all the remote joins while modifying the AST to add necessary join fields where needed.

1. Once the remote joins are collected from the AST, the database call is made to fetch the response. The necessary data for the remote join(s) is collected from the database's response and one or more remote schema calls are constructed as necessary.

1. The remote schema calls are then executed and the data from the database and from the remote schemas is joined to produce the final response.

### Known issues

1. Ideally the traversal of the IR to collect remote joins should return an AST which does not include remote join fields. This operation can be type safe but isn't taken up as part of the PR.

1. There is a lot of code duplication between `Transport/HTTP.hs` and `Transport/Websocket.hs` which needs to be fixed ASAP. This too hasn't been taken up by this PR.

1. The type which represents the execution plan is only modified to handle our current remote joins and as such it will have to be changed to accommodate general remote joins.

1. Use of lenses would have reduced the boilerplate code to collect remote joins from the base AST.

1. The current remote join logic assumes that the join columns of a remote relationship appear with their names in the database response. This however is incorrect as they could be aliased. This can be taken up by anyone, I've left a comment in the code.

### Notes to the reviewers

I think it is best reviewed commit by commit.

1. The first one is very straight forward.

1. The second one refactors the remote join execution logic but other than moving things around, it doesn't change the user facing functionality.  This moves Postgres specific parts to `Backends/Postgres` module from `Execute`. Some IR related code to `Hasura.RQL.IR` module.  Simplifies various type class function signatures as a backend doesn't have to handle remote joins anymore

1. The third one fixes partial case matches that for some weird reason weren't shown as warnings before this refactor

1. The fourth one generalizes the validation logic of remote relationships and implements `scalarTypeGraphQLName` function on SQL Server and BigQuery which is used by the validation logic. This enables remote relationships on BigQuery and SQL Server.

https://github.com/hasura/graphql-engine-mono/pull/1497

GitOrigin-RevId: 77dd8eed326602b16e9a8496f52f46d22b795598
2021-06-11 03:27:39 +00:00

115 lines
5.1 KiB
Haskell

module Hasura.GraphQL.Execute.Mutation
( convertMutationSelectionSet
) where
import Hasura.Prelude
import qualified Data.Environment as Env
import qualified Data.HashMap.Strict as Map
import qualified Data.HashMap.Strict.InsOrd as OMap
import qualified Language.GraphQL.Draft.Syntax as G
import qualified Network.HTTP.Client as HTTP
import qualified Network.HTTP.Types as HTTP
import qualified Hasura.GraphQL.Execute.RemoteJoin.Collect as RJ
import qualified Hasura.GraphQL.Transport.HTTP.Protocol as GH
import qualified Hasura.Logging as L
import qualified Hasura.SQL.AnyBackend as AB
import qualified Hasura.Tracing as Tracing
import Hasura.Base.Error
import Hasura.GraphQL.Context
import Hasura.GraphQL.Execute.Action
import Hasura.GraphQL.Execute.Backend
import Hasura.GraphQL.Execute.Common
import Hasura.GraphQL.Execute.Instances ()
import Hasura.GraphQL.Execute.Remote
import Hasura.GraphQL.Execute.Resolve
import Hasura.GraphQL.Parser
import Hasura.GraphQL.Parser.Directives
import Hasura.Metadata.Class
import Hasura.RQL.IR
import Hasura.RQL.Types
import Hasura.Server.Version (HasVersion)
import Hasura.Session
convertMutationAction
::( HasVersion
, MonadIO m
, MonadError QErr m
, MonadMetadataStorage (MetadataStorageT m)
)
=> Env.Environment
-> L.Logger L.Hasura
-> UserInfo
-> HTTP.Manager
-> HTTP.RequestHeaders
-> ActionMutation ('Postgres 'Vanilla) (UnpreparedValue ('Postgres 'Vanilla))
-> m ActionExecutionPlan
convertMutationAction env logger userInfo manager reqHeaders = \case
AMSync s -> pure $ AEPSync $ resolveActionExecution env logger userInfo s actionExecContext
AMAsync s -> AEPAsyncMutation <$>
liftEitherM (runMetadataStorageT $ resolveActionMutationAsync s reqHeaders userSession)
where
userSession = _uiSession userInfo
actionExecContext = ActionExecContext manager reqHeaders $ _uiSession userInfo
convertMutationSelectionSet
:: forall m
. ( HasVersion
, Tracing.MonadTrace m
, MonadIO m
, MonadError QErr m
, MonadMetadataStorage (MetadataStorageT m)
, MonadGQLExecutionCheck m
)
=> Env.Environment
-> L.Logger L.Hasura
-> GQLContext
-> SQLGenCtx
-> UserInfo
-> HTTP.Manager
-> HTTP.RequestHeaders
-> [G.Directive G.Name]
-> G.SelectionSet G.NoFragments G.Name
-> [G.VariableDefinition]
-> Maybe GH.VariableValues
-> SetGraphqlIntrospectionOptions
-> m (ExecutionPlan, G.SelectionSet G.NoFragments Variable)
convertMutationSelectionSet env logger gqlContext SQLGenCtx{stringifyNum} userInfo manager reqHeaders directives fields varDefs varValsM introspectionDisabledRoles = do
mutationParser <- onNothing (gqlMutationParser gqlContext) $
throw400 ValidationFailed "no mutations exist"
(resolvedDirectives, resolvedSelSet) <- resolveVariables varDefs (fromMaybe Map.empty varValsM) directives fields
-- Parse the GraphQL query into the RQL AST
(unpreparedQueries, _reusability)
:: (OMap.InsOrdHashMap G.Name (MutationRootField UnpreparedValue), QueryReusability)
<-(mutationParser >>> (`onLeft` reportParseErrors)) resolvedSelSet
-- Process directives on the mutation
(_dirMap, _) <- (`onLeft` reportParseErrors) =<<
runParseT (parseDirectives customDirectives (G.DLExecutable G.EDLMUTATION) resolvedDirectives)
-- Transform the RQL AST into a prepared SQL query
txs <- for unpreparedQueries \case
RFDB sourceName exists ->
AB.dispatchAnyBackend @BackendExecute exists
\(SourceConfigWith sourceConfig (MDBR db)) -> do
let (noRelsDBAST, remoteJoins) = RJ.getRemoteJoinsMutationDB db
dbStepInfo <- mkDBMutationPlan userInfo stringifyNum sourceName sourceConfig noRelsDBAST
pure $ ExecStepDB [] (AB.mkAnyBackend dbStepInfo) remoteJoins
RFRemote remoteField -> do
RemoteFieldG remoteSchemaInfo resolvedRemoteField <- runVariableCache $ resolveRemoteField userInfo remoteField
pure $ buildExecStepRemote remoteSchemaInfo G.OperationTypeMutation $ [G.SelectionField resolvedRemoteField]
RFAction action -> do
let (noRelsDBAST, remoteJoins) = RJ.getRemoteJoinsActionMutation action
(actionName, _fch) <- pure $ case noRelsDBAST of
AMSync s -> (_aaeName s, _aaeForwardClientHeaders s)
AMAsync s -> (_aamaName s, _aamaForwardClientHeaders s)
plan <- convertMutationAction env logger userInfo manager reqHeaders noRelsDBAST
pure $ ExecStepAction plan (ActionsInfo actionName _fch) remoteJoins -- `_fch` represents the `forward_client_headers` option from the action
-- definition which is currently being ignored for actions that are mutations
RFRaw s -> flip onLeft throwError =<< executeIntrospection userInfo s introspectionDisabledRoles
return (txs, resolvedSelSet)