diff options
Diffstat (limited to 'Data/GraphQL/Execute.hs')
| -rw-r--r-- | Data/GraphQL/Execute.hs | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/Data/GraphQL/Execute.hs b/Data/GraphQL/Execute.hs index 47d1d03..86887ff 100644 --- a/Data/GraphQL/Execute.hs +++ b/Data/GraphQL/Execute.hs @@ -1,4 +1,6 @@ {-# LANGUAGE CPP #-} +-- | This module provides the function to execute a @GraphQL@ request -- +-- according to a 'Schema'. module Data.GraphQL.Execute (execute) where #if !MIN_VERSION_base(4,8,0) @@ -13,16 +15,32 @@ import Data.GraphQL.AST import Data.GraphQL.Schema (Schema(..)) import qualified Data.GraphQL.Schema as Schema -execute - :: Alternative f +import Data.GraphQL.Error + +-- | Takes a 'Schema', a variable substitution function ('Schema.Subs'), and a +-- @GraphQL@ 'document'. The substitution is applied to the document using +-- 'rootFields', and the 'Schema''s resolvers are applied to the resulting fields. +-- +-- Returns the result of the query against the 'Schema' wrapped in a /data/ field, or +-- errors wrapped in an /errors/ field. +execute :: Alternative f => Schema.Schema f -> Schema.Subs -> Document -> f Aeson.Value -execute (Schema resolvs) subs = Schema.resolvers resolvs . rootFields subs +execute (Schema resolvs) subs doc = runCollectErrs res + where res = Schema.resolvers resolvs $ rootFields subs doc +-- | Takes a variable substitution function and a @GraphQL@ document. +-- If the document contains one query (and no other definitions) +-- it applies the substitution to the query's set of selections +-- and then returns their fields. rootFields :: Schema.Subs -> Document -> [Field] rootFields subs (Document [DefinitionOperation (Query (Node _varDefs _ _ sels))]) = Schema.fields $ substitute subs <$> sels rootFields _ _ = [] +-- | Takes a variable substitution function and a selection. If the +-- selection is a field it applies the substitution to the field's +-- arguments using 'subsArg', and recursively applies the substitution to +-- the arguments of fields nested in the primary field. substitute :: Schema.Subs -> Selection -> Selection substitute subs (SelectionField (Field alias name args directives sels)) = SelectionField $ Field @@ -35,6 +53,9 @@ substitute subs (SelectionField (Field alias name args directives sels)) = substitute _ sel = sel -- TODO: Support different value types +-- | Takes a variable substitution function and an argument. If the +-- argument's value is a variable the substitution is applied to the +-- variable's name. subsArg :: Schema.Subs -> Argument -> Maybe Argument subsArg subs (Argument n (ValueVariable (Variable v))) = Argument n . ValueString <$> subs v |