graphql-engine/server/src-lib/Hasura/GraphQL/Execute/RemoteJoin/Collect.hs
jkachmar 4a83bb1834 Remote schema execution logic
https://github.com/hasura/graphql-engine-mono/pull/1995

Co-authored-by: David Overton <7734777+dmoverton@users.noreply.github.com>
GitOrigin-RevId: 178669089ec5e63b1f3da1d3ba0a9f8debbc108d
2021-08-06 13:40:37 +00:00

438 lines
19 KiB
Haskell

module Hasura.GraphQL.Execute.RemoteJoin.Collect
( getRemoteJoins
, getRemoteJoinsSelect
, getRemoteJoinsMutationDB
, getRemoteJoinsActionQuery
, getRemoteJoinsActionMutation
) where
import Hasura.Prelude
import qualified Data.HashMap.Strict as Map
import qualified Data.List.NonEmpty as NE
import qualified Data.Text as T
import Control.Lens (Traversal', _2, preview)
import Control.Monad.Writer
import Hasura.GraphQL.Execute.RemoteJoin.Types
import Hasura.GraphQL.Parser.Column (UnpreparedValue (..))
import Hasura.RQL.IR
import Hasura.RQL.IR.Returning
import Hasura.RQL.Types
{- Note: [Remote Joins Architecture]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Unparsed Incoming GraphQL +------------------------------+
--------------------------> | Parsing of the GraphQL query |-----+
+------------------------------+ |
| DB Query and remote joins (if any)
|
V
+----------------------------------+ SQL query response +----------------------------+
| Traverse the DB response to | <------------------- | Execution of the DB query |
| get the values of the arguments | +----------------------------+
| of the remote field |
+----------------------------------+
|
| Remote field arguments
V
+--------------------------+ Remote schema response +----------------------------------------+
| Query the remote schema | ------------------------> | Replace the remote join fields in |
| with the remote field | | the SQL query response (JSON) with |
| arguments to the remote | | the response obtained from the remote |
| field configured in the | | schema at appropriate places. |
| remote join. | +----------------------------------------+
+--------------------------+
-}
-- | A writer monad used to collect together all remote joins
-- appearing in some data structure.
--
-- In the functions below, the 'withField' function is used to track the
-- context of the path from the root of the current selection set.
--
-- It is important that we work bottom-up, and do not 'collect' duplicate
-- field names at any level, because the 'Semigroup' instance for 'RemoteJoins'
-- does not allow for these duplicates.
newtype Collector a = Collector { runCollector :: (a, Maybe RemoteJoins) }
deriving (Functor, Applicative, Monad, MonadWriter (Maybe RemoteJoins))
via Writer (Maybe RemoteJoins)
-- | Collect some remote joins appearing at the given field names in the current
-- context.
collect :: NonEmpty (FieldName, RemoteJoin) -> Collector ()
collect = tell . Just . JoinTree . fmap (second Leaf)
-- | Keep track of the given field name in the current path from the root of the
-- selection set.
withField :: FieldName -> Collector a -> Collector a
withField name = censor (fmap wrap) where
wrap rjs = JoinTree ((name, Tree rjs) :| [])
-- | Collects remote joins from the AST and also adds the necessary join fields
getRemoteJoins
:: Backend b
=> QueryDB b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (QueryDB b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoins = \case
QDBMultipleRows s -> first QDBMultipleRows $ getRemoteJoinsSelect s
QDBSingleRow s -> first QDBSingleRow $ getRemoteJoinsSelect s
QDBAggregation s -> first QDBAggregation $ getRemoteJoinsAggregateSelect s
QDBConnection s -> first QDBConnection $ getRemoteJoinsConnectionSelect s
-- | Traverse through 'AnnSimpleSel' and collect remote join fields (if any).
getRemoteJoinsSelect
:: Backend b
=> AnnSimpleSelectG b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (AnnSimpleSelectG b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsSelect =
runCollector . transformSelect
-- | Traverse through @'AnnAggregateSelect' and collect remote join fields (if any).
getRemoteJoinsAggregateSelect
:: Backend b
=> AnnAggregateSelectG b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (AnnAggregateSelectG b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsAggregateSelect =
runCollector . transformAggregateSelect
-- | Traverse through @'ConnectionSelect' and collect remote join fields (if any).
getRemoteJoinsConnectionSelect
:: Backend b
=> ConnectionSelect b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (ConnectionSelect b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsConnectionSelect =
runCollector . transformConnectionSelect
-- | Traverse through 'MutationOutput' and collect remote join fields (if any)
getRemoteJoinsMutationOutput
:: Backend b
=> MutationOutputG b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (MutationOutputG b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsMutationOutput =
runCollector . transformMutationOutput
where
transformMutationOutput = \case
MOutMultirowFields mutationFields ->
MOutMultirowFields <$> transfromMutationFields mutationFields
MOutSinglerowObject annFields ->
MOutSinglerowObject <$> transformAnnFields annFields
where
transfromMutationFields fields =
for fields $ \(fieldName, field') -> withField fieldName do
(fieldName,) <$> case field' of
MCount -> pure MCount
MExp t -> pure $ MExp t
MRet annFields -> MRet <$> transformAnnFields annFields
-- local helpers
getRemoteJoinsAnnFields
:: Backend b
=> AnnFieldsG b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (AnnFieldsG b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsAnnFields =
runCollector . transformAnnFields
getRemoteJoinsMutationDB
:: Backend b
=> MutationDB b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (MutationDB b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsMutationDB = \case
MDBInsert insert ->
first MDBInsert $ getRemoteJoinsInsert insert
MDBUpdate update ->
first MDBUpdate $ getRemoteJoinsUpdate update
MDBDelete delete ->
first MDBDelete $ getRemoteJoinsDelete delete
MDBFunction aggSelect select ->
first (MDBFunction aggSelect) $ getRemoteJoinsSelect select
where
getRemoteJoinsInsert insert =
let (output', remoteJoins) = getRemoteJoinsMutationOutput $ _aiOutput insert
in (insert{ _aiOutput = output'}, remoteJoins)
getRemoteJoinsUpdate update =
let (output', remoteJoins) = getRemoteJoinsMutationOutput $ uqp1Output update
in (update{ uqp1Output = output'}, remoteJoins)
getRemoteJoinsDelete delete =
let (output', remoteJoins) = getRemoteJoinsMutationOutput $ dqp1Output delete
in (delete{ dqp1Output = output'}, remoteJoins)
getRemoteJoinsSyncAction
:: (Backend b)
=> AnnActionExecution b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (AnnActionExecution b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsSyncAction actionExecution =
let (fields', remoteJoins) = getRemoteJoinsAnnFields $ _aaeFields actionExecution
in (actionExecution { _aaeFields = fields' }, remoteJoins)
getRemoteJoinsActionQuery
:: (Backend b)
=> ActionQuery b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (ActionQuery b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsActionQuery = \case
AQQuery sync ->
first AQQuery $ getRemoteJoinsSyncAction sync
AQAsync async ->
first AQAsync $ getRemoteJoinsAsyncQuery async
where
getRemoteJoinsAsyncQuery async =
let (fields', remoteJoins) =
runCollector . transformAsyncFields $
_aaaqFields async
in (async { _aaaqFields = fields' }, remoteJoins)
transformAsyncFields fields =
for fields $ \(fieldName, field) -> withField fieldName do
(fieldName,) <$> case field of
AsyncTypename t -> pure $ AsyncTypename t
AsyncOutput outputFields ->
AsyncOutput <$> transformAnnFields outputFields
AsyncId -> pure AsyncId
AsyncCreatedAt -> pure AsyncCreatedAt
AsyncErrors -> pure AsyncErrors
getRemoteJoinsActionMutation
:: (Backend b)
=> ActionMutation b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> (ActionMutation b (Const Void) (UnpreparedValue b), Maybe RemoteJoins)
getRemoteJoinsActionMutation = \case
AMAsync async -> (AMAsync async, Nothing)
AMSync sync -> first AMSync $ getRemoteJoinsSyncAction sync
transformSelect
:: Backend b
=> AnnSimpleSelectG b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> Collector (AnnSimpleSelectG b (Const Void) (UnpreparedValue b))
transformSelect select@AnnSelectG{_asnFields = fields} = do
-- Transform selects in array, object and computed fields
transformedFields <- transformAnnFields fields
pure select{_asnFields = transformedFields}
transformAggregateSelect
:: Backend b
=> AnnAggregateSelectG b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> Collector (AnnAggregateSelectG b (Const Void) (UnpreparedValue b))
transformAggregateSelect select@AnnSelectG{_asnFields = aggFields} = do
transformedFields <- for aggFields \(fieldName, aggField) ->
withField fieldName $ case aggField of
TAFAgg agg -> pure (fieldName, TAFAgg agg)
TAFExp t -> pure (fieldName, TAFExp t)
TAFNodes nodesAgg annFields -> do
transformed <- transformAnnFields annFields
pure (fieldName, TAFNodes nodesAgg transformed)
pure select{_asnFields = transformedFields}
transformConnectionSelect
:: forall b. Backend b
=> ConnectionSelect b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> Collector (ConnectionSelect b (Const Void) (UnpreparedValue b))
transformConnectionSelect connSelect@ConnectionSelect{..} = do
transformedFields <- for (_asnFields _csSelect) \(fieldName, connField) ->
withField fieldName $ case connField of
ConnectionTypename t -> pure (fieldName, ConnectionTypename t)
ConnectionPageInfo p -> pure (fieldName, ConnectionPageInfo p)
ConnectionEdges edges -> do
transformed <- transformEdges edges
pure (fieldName, ConnectionEdges transformed)
let select = _csSelect{_asnFields = transformedFields}
pure connSelect{ _csSelect = select }
where
transformEdges
:: [(FieldName, EdgeField b (RemoteSelect UnpreparedValue) (UnpreparedValue b))]
-> Collector [(FieldName, EdgeField b (Const Void) (UnpreparedValue b))]
transformEdges edgeFields = for edgeFields \(fieldName, edgeField) ->
withField fieldName $ case edgeField of
EdgeTypename t -> pure (fieldName, EdgeTypename t)
EdgeCursor -> pure (fieldName, EdgeCursor)
EdgeNode annFields -> do
transformed <- transformAnnFields annFields
pure (fieldName, EdgeNode transformed)
transformObjectSelect
:: Backend b
=> AnnObjectSelectG b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> Collector (AnnObjectSelectG b (Const Void) (UnpreparedValue b))
transformObjectSelect select@AnnObjectSelectG{_aosFields = fields} = do
transformedFields <- transformAnnFields fields
pure select{_aosFields = transformedFields}
transformAnnFields
:: forall b . Backend b
=> AnnFieldsG b (RemoteSelect UnpreparedValue) (UnpreparedValue b)
-> Collector (AnnFieldsG b (Const Void) (UnpreparedValue b))
transformAnnFields fields = do
-- Produces a list of transformed fields that may or may not have an
-- associated remote join.
annotatedFields <- for fields \(fieldName, field') -> withField fieldName do
-- FIXME: There's way too much going on in this 'case .. of' block...
(fieldName,) <$> case field' of
-- AnnFields which do not need to be transformed.
AFNodeId x qt pkeys -> pure (AFNodeId x qt pkeys, Nothing)
AFColumn c -> pure (AFColumn c, Nothing)
AFExpression t -> pure (AFExpression t, Nothing)
-- AnnFields with no associated remote joins and whose transformations are
-- relatively straightforward.
AFObjectRelation annRel -> do
transformed <- transformAnnRelation transformObjectSelect annRel
pure (AFObjectRelation transformed, Nothing)
AFArrayRelation (ASSimple annRel) -> do
transformed <- transformAnnRelation transformSelect annRel
pure (AFArrayRelation . ASSimple $ transformed, Nothing)
AFArrayRelation (ASAggregate aggRel) -> do
transformed <- transformAnnRelation transformAggregateSelect aggRel
pure (AFArrayRelation . ASAggregate $ transformed, Nothing)
AFArrayRelation (ASConnection annRel) -> do
transformed <- transformAnnRelation transformConnectionSelect annRel
pure (AFArrayRelation . ASConnection $ transformed, Nothing)
AFComputedField computedField computedFieldName computedFieldSelect -> do
transformed <- case computedFieldSelect of
CFSScalar cfss cbe -> pure $ CFSScalar cfss cbe
CFSTable jsonAggSel annSel -> do
transformed <- transformSelect annSel
pure $ CFSTable jsonAggSel transformed
pure (AFComputedField computedField computedFieldName transformed, Nothing)
-- Remote AnnFields, whose elements require annotation so that they can be
-- used to construct a remote join.
--
-- We generate this so that the response has a key with the relationship,
-- without which preserving the order of fields in the final response
-- would require a lot of bookkeeping.
AFRemote (RemoteSelectRemoteSchema RemoteSchemaSelect{..}) ->
let
annotatedJoinColumns =
Map.fromList $ map annotateDBJoinField (toList _rselHasuraFields)
phantomColumns = annotatedJoinColumns & Map.mapMaybe \(columnInfo, alias) ->
case alias of
JCSelected _ -> Nothing
JCPhantom a -> Just (columnInfo, a)
joinColumnAliases = fmap snd annotatedJoinColumns
inputArgsToMap = Map.fromList . map (_rfaArgument &&& _rfaValue)
remoteJoin = RemoteJoinRemoteSchema $ RemoteSchemaJoin
(inputArgsToMap _rselArgs)
_rselResultCustomizer
_rselSelection
joinColumnAliases
_rselFieldCall
_rselRemoteSchema
annotatedJoin = Just (phantomColumns, remoteJoin)
in
pure (remoteAnnPlaceholder, annotatedJoin)
let
transformedFields = (fmap . fmap) fst annotatedFields
remoteJoins = annotatedFields & mapMaybe \(fieldName, (_, mRemoteJoin)) ->
mRemoteJoin <&> \remoteJoin -> (fieldName, remoteJoin)
case NE.nonEmpty remoteJoins of
Nothing -> pure transformedFields
Just neRemoteJoins -> do
let
phantomFields =
(Map.elems . Map.unions . map (fst . snd) $ remoteJoins) <&>
\(joinField, alias) -> case joinField of
JoinColumn columnInfo ->
let column = AFColumn $ AnnColumnField columnInfo False Nothing Nothing
in (alias, column)
JoinComputedField computedFieldInfo ->
(alias, mkScalarComputedFieldSelect computedFieldInfo)
collect $ (fmap . fmap) snd neRemoteJoins
pure $ transformedFields <> phantomFields
where
-- Placeholder text to annotate a remote relationship field.
remoteAnnPlaceholder :: AnnFieldG b (Const Void) (UnpreparedValue b)
remoteAnnPlaceholder = AFExpression "remote relationship placeholder"
-- Annotate a 'DBJoinField' with its field name and an alias so that it may
-- be used to construct a remote join.
annotateDBJoinField :: DBJoinField b -> (FieldName, (DBJoinField b, JoinColumnAlias))
annotateDBJoinField = \case
jc@(JoinColumn columnInfo) ->
let
column = pgiColumn columnInfo
columnFieldName = fromCol @b $ column
alias = getJoinColumnAlias columnFieldName column columnFields
in
(columnFieldName, (jc, alias))
jcf@(JoinComputedField ScalarComputedField{..}) ->
let
computedFieldName = fromComputedField _scfName
alias = getJoinColumnAlias computedFieldName _scfName computedFields
in
(computedFieldName, (jcf, alias))
-- Get the fields targeted by some 'Traversal' for an arbitrary list of
-- tuples, discarding any elements whose fields cannot be focused upon.
getFields :: Traversal' super sub -> [(any, super)] -> [(any, sub)]
getFields focus = mapMaybe (traverse $ preview focus)
-- This is a map of column name to its alias of all columns in the
-- selection set.
columnFields :: HashMap (Column b) FieldName
columnFields = Map.fromList $
[ (pgiColumn . _acfInfo $ annColumn, alias)
| (alias, annColumn) <- getFields _AFColumn fields
]
-- This is a map of computed field name to its alias of all computed fields
-- in the selection set.
computedFields :: Map.HashMap ComputedFieldName FieldName
computedFields = Map.fromList $
[ (fieldName, alias)
-- Note that we do not currently care about input arguments to a computed
-- field because only computed fields which do not accept input arguments
-- are currently allowed.
| (alias, fieldName) <- getFields (_AFComputedField._2) fields
]
getJoinColumnAlias
:: (Eq field, Hashable field)
=> FieldName
-> field
-> HashMap field FieldName
-> JoinColumnAlias
getJoinColumnAlias fieldName field selectedFields =
case Map.lookup field selectedFields of
Nothing -> makeUniqueAlias fieldName
Just fieldAlias -> JCSelected fieldAlias
longestAliasLength = maximum $ map (T.length . coerce . fst) fields
-- This generates an alias for a phantom field that does not conflict with
-- any of the existing aliases in the seleciton set
--
-- If we generate a unique name for each field name which is longer than
-- the longest alias in the selection set, the generated name would be
-- unique
makeUniqueAlias :: FieldName -> JoinColumnAlias
makeUniqueAlias fieldName =
let suffix = "_join_column" <>
-- 12 is the length of "_join_column"
T.replicate ((longestAliasLength - (T.length (coerce fieldName) + 12)) + 1) "_"
in JCPhantom $ fieldName <> FieldName suffix
transformAnnRelation
:: (t -> Collector a)
-> AnnRelationSelectG b t
-> Collector (AnnRelationSelectG b a)
transformAnnRelation transform relation@(AnnRelationSelectG _ _ select) = do
transformedSelect <- transform select
pure $ relation{ aarAnnSelect = transformedSelect }
mkScalarComputedFieldSelect
:: ScalarComputedField b
-> (AnnFieldG b (Const Void) (UnpreparedValue b))
mkScalarComputedFieldSelect ScalarComputedField{..} =
let functionArgs = flip FunctionArgsExp mempty
$ functionArgsWithTableRowAndSession UVSession _scfTableArgument _scfSessionArgument
fieldSelect = flip CFSScalar Nothing
$ ComputedFieldScalarSelect _scfFunction functionArgs _scfType Nothing
in AFComputedField _scfXField _scfName fieldSelect