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Diffstat (limited to 'docs/tutorial')
| -rw-r--r-- | docs/tutorial/test.hs | 55 | ||||
| -rw-r--r-- | docs/tutorial/tutorial.lhs | 9 |
2 files changed, 58 insertions, 6 deletions
diff --git a/docs/tutorial/test.hs b/docs/tutorial/test.hs new file mode 100644 index 0000000..631407c --- /dev/null +++ b/docs/tutorial/test.hs @@ -0,0 +1,55 @@ +{-# LANGUAGE OverloadedStrings #-} + +import qualified Data.Aeson as Aeson +import qualified Data.ByteString.Lazy.Char8 as ByteString.Lazy.Char8 +import qualified Data.HashMap.Strict as HashMap +import Language.GraphQL +import Language.GraphQL.Type +import qualified Language.GraphQL.Type.Out as Out + +-- GraphQL supports 3 kinds of operations: queries, mutations and subscriptions. +-- Our first schema supports only queries. +citeSchema :: Schema IO +citeSchema = schema queryType + +-- GraphQL distinguishes between input and output types. Input types are field +-- argument types and they are defined in Language.GraphQL.Type.In. Output types +-- are result types, they are defined in Language.GraphQL.Type.Out. Root types +-- are always object types. +-- +-- Here we define a type "Query". The second argument is an optional +-- description, the third one is the list of interfaces implemented by the +-- object type. The last argument is a field map. Keys are field names, values +-- are field definitions and resolvers. Resolvers are the functions, where the +-- actual logic lives, they return values for the respective fields. +queryType :: Out.ObjectType IO +queryType = Out.ObjectType "Query" (Just "Root Query type.") [] + $ HashMap.singleton "cite" citeResolver + where + -- 'ValueResolver' is a 'Resolver' data constructor, it combines a field + -- definition with its resolver function. This function resolves a value for + -- a field (as opposed to the 'EventStreamResolver' used by subscriptions). + -- Our resolver just returns a constant value. + citeResolver = ValueResolver citeField + $ pure "Piscis primum a capite foetat" + + -- The first argument is an optional field description. The second one is + -- the field type and the third one is for arguments (we have none in this + -- example). + -- + -- GraphQL has named and wrapping types. String is a scalar, named type. + -- Named types are nullable by default. To make our "cite" field + -- non-nullable, we wrap it in the wrapping type, Non-Null. + citeField = Out.Field + (Just "Provides a cite.") (Out.NonNullScalarType string) HashMap.empty + +-- Now we can execute a query. Since our schema defines only one field, +-- everything we can do is to ask to resolve it and give back the result. +-- Since subscriptions don't return plain values, the 'graphql' function returns +-- an 'Either'. 'Left' is for subscriptions, 'Right' is for queries and +-- mutations. +main :: IO () +main = do + Right result <- graphql citeSchema "{ cite }" + ByteString.Lazy.Char8.putStrLn $ Aeson.encode result + diff --git a/docs/tutorial/tutorial.lhs b/docs/tutorial/tutorial.lhs index dc44c1e..6a68e35 100644 --- a/docs/tutorial/tutorial.lhs +++ b/docs/tutorial/tutorial.lhs @@ -39,8 +39,7 @@ Now, as our first example, we are going to look at the example from First we build a GraphQL schema. > schema1 :: Schema IO -> schema1 = Schema -> { query = queryType , mutation = Nothing , subscription = Nothing } +> schema1 = schema queryType > > queryType :: ObjectType IO > queryType = ObjectType "Query" Nothing [] @@ -77,8 +76,7 @@ This runs the query by fetching the one field defined, returning For this example, we're going to be using time. > schema2 :: Schema IO -> schema2 = Schema -> { query = queryType2, mutation = Nothing, subscription = Nothing } +> schema2 = schema queryType2 > > queryType2 :: ObjectType IO > queryType2 = ObjectType "Query" Nothing [] @@ -115,8 +113,7 @@ This runs the query, returning the current time Now that we have two resolvers, we can define a schema which uses them both. > schema3 :: Schema IO -> schema3 = Schema -> { query = queryType3, mutation = Nothing, subscription = Nothing } +> schema3 = schema queryType3 > > queryType3 :: ObjectType IO > queryType3 = ObjectType "Query" Nothing [] $ HashMap.fromList |