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Diffstat (limited to 'docs/tutorial/tutorial.lhs')
| -rw-r--r-- | docs/tutorial/tutorial.lhs | 56 |
1 files changed, 18 insertions, 38 deletions
diff --git a/docs/tutorial/tutorial.lhs b/docs/tutorial/tutorial.lhs index 06494a2..00ad98d 100644 --- a/docs/tutorial/tutorial.lhs +++ b/docs/tutorial/tutorial.lhs @@ -5,7 +5,7 @@ title: GraphQL Haskell Tutorial == Getting started == -Welcome to graphql-haskell! +Welcome to GraphQL! We have written a small tutorial to help you (and ourselves) understand the graphql package. @@ -39,16 +39,18 @@ 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 queryType Nothing +> schema1 = Schema +> { query = queryType , mutation = Nothing , subscription = Nothing } > > queryType :: ObjectType IO > queryType = ObjectType "Query" Nothing [] -> $ HashMap.singleton "hello" helloField +> $ HashMap.singleton "hello" +> $ ValueResolver helloField hello > > helloField :: Field IO -> helloField = Field Nothing (Out.NamedScalarType string) mempty hello +> helloField = Field Nothing (Out.NamedScalarType string) mempty > -> hello :: ResolverT IO Value +> hello :: Resolve IO > hello = pure $ String "it's me" This defines a simple schema with one type and one field, that resolves to a @@ -74,16 +76,18 @@ 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 queryType2 Nothing +> schema2 = Schema +> { query = queryType2, mutation = Nothing, subscription = Nothing } > > queryType2 :: ObjectType IO > queryType2 = ObjectType "Query" Nothing [] -> $ HashMap.singleton "time" timeField +> $ HashMap.singleton "time" +> $ ValueResolver timeField time > > timeField :: Field IO -> timeField = Field Nothing (Out.NamedScalarType string) mempty time +> timeField = Field Nothing (Out.NamedScalarType string) mempty > -> time :: ResolverT IO Value +> time :: Resolve IO > time = do > t <- liftIO getCurrentTime > pure $ String $ Text.pack $ show t @@ -104,42 +108,18 @@ This runs the query, returning the current time ```{"data": {"time":"2016-03-08 23:28:14.546899 UTC"}}``` -=== Errors === - -Errors are handled according to the spec, with fields that cause erros being -resolved to `null`, and an error being added to the error list. - -An example of this is the following query: - -> queryShouldFail :: Text -> queryShouldFail = "{ boyhowdy }" - -Since there is no `boyhowdy` field in our schema, it will not resolve, and the -query will fail, as we can see in the following example. - -> mainShouldFail :: IO () -> mainShouldFail = do -> failure <- graphql schema1 queryShouldFail -> putStrLn $ encode failure - -This outputs: - -``` -{"data": {"boyhowdy": null}, "errors":[{"message": "the field boyhowdy did not resolve."}]} -``` - - === Combining resolvers === Now that we have two resolvers, we can define a schema which uses them both. > schema3 :: Schema IO -> schema3 = Schema queryType3 Nothing +> schema3 = Schema +> { query = queryType3, mutation = Nothing, subscription = Nothing } > > queryType3 :: ObjectType IO > queryType3 = ObjectType "Query" Nothing [] $ HashMap.fromList -> [ ("hello", helloField) -> , ("time", timeField) +> [ ("hello", ValueResolver helloField hello) +> , ("time", ValueResolver timeField time) > ] > > query3 :: Text @@ -166,4 +146,4 @@ directory, in the [Test.StarWars](../../tests/Test/StarWars) module. This includes a more complex schema, and more complex queries. > main :: IO () -> main = main1 >> main2 >> mainShouldFail >> main3 +> main = main1 >> main2 >> main3 |