Default to generic ScalarValue in #[graphql_object] macro

docs/book/content/advanced/introspection.md

@@ -33,11 +33,14 @@ result can then be converted to JSON for use with tools and libraries such as
 # #![allow(unused_variables)]
 # extern crate juniper;
 # extern crate serde_json;
-use juniper::{EmptyMutation, EmptySubscription, FieldResult, IntrospectionFormat};
+use juniper::{
+    graphql_object, EmptyMutation, EmptySubscription, FieldResult, 
+    GraphQLObject, IntrospectionFormat,
+};
 
 // Define our schema.
 
-#[derive(juniper::GraphQLObject)]
+#[derive(GraphQLObject)]
 struct Example {
   id: String,
 }
@@ -47,9 +50,7 @@ impl juniper::Context for Context {}
 
 struct Query;
 
-#[juniper::graphql_object(
-  Context = Context,
-)]
+#[graphql_object(context = Context)]
 impl Query {
    fn example(id: String) -> FieldResult<Example> {
        unimplemented!()

docs/book/content/advanced/non_struct_objects.md

@@ -10,9 +10,10 @@ errors from a mutation:
 
 ```rust
 # extern crate juniper;
+# use juniper::{graphql_object, GraphQLObject};
 # #[derive(juniper::GraphQLObject)] struct User { name: String }
-
-#[derive(juniper::GraphQLObject)]
+#
+#[derive(GraphQLObject)]
 struct ValidationError {
     field: String,
     message: String,
@@ -24,7 +25,7 @@ enum SignUpResult {
     Error(Vec<ValidationError>),
 }
 
-#[juniper::graphql_object]
+#[graphql_object]
 impl SignUpResult {
     fn user(&self) -> Option<&User> {
         match *self {
@@ -40,7 +41,7 @@ impl SignUpResult {
         }
     }
 }
-
+#
 # fn main() {}
 ```
 

docs/book/content/advanced/subscriptions.md

@@ -29,7 +29,7 @@ sequentially:
 # extern crate juniper;
 # extern crate juniper_subscriptions;
 # extern crate tokio;
-# use juniper::FieldError;
+# use juniper::{graphql_object, graphql_subscription, FieldError};
 # use futures::Stream;
 # use std::pin::Pin;
 #
@@ -38,7 +38,7 @@ sequentially:
 # impl juniper::Context for Database {}
 
 # pub struct Query;
-# #[juniper::graphql_object(Context = Database)]
+# #[graphql_object(context = Database)]
 # impl Query {
 #    fn hello_world() -> &str {
 #        "Hello World!"
@@ -48,7 +48,7 @@ pub struct Subscription;
 
 type StringStream = Pin<Box<dyn Stream<Item = Result<String, FieldError>> + Send>>;
 
-#[juniper::graphql_subscription(Context = Database)]
+#[graphql_subscription(context = Database)]
 impl Subscription {
     async fn hello_world() -> StringStream {
         let stream = tokio::stream::iter(vec![
@@ -58,8 +58,9 @@ impl Subscription {
         Box::pin(stream)
     }
 }
+#
 # fn main () {}
-```         
+```
 
 
 
@@ -84,8 +85,12 @@ where [`Connection`][Connection] is a `Stream` of values returned by the operati
 # extern crate juniper_subscriptions;
 # extern crate serde_json;
 # extern crate tokio;
-# use juniper::http::GraphQLRequest;
-# use juniper::{DefaultScalarValue, EmptyMutation, FieldError, RootNode, SubscriptionCoordinator};
+# use juniper::{
+#     http::GraphQLRequest,
+#     graphql_object, graphql_subscription, 
+#     DefaultScalarValue, EmptyMutation, FieldError, 
+#     RootNode, SubscriptionCoordinator,
+# };
 # use juniper_subscriptions::Coordinator;
 # use futures::{Stream, StreamExt};
 # use std::pin::Pin;
@@ -103,7 +108,7 @@ where [`Connection`][Connection] is a `Stream` of values returned by the operati
 # 
 # pub struct Query;
 # 
-# #[juniper::graphql_object(Context = Database)]
+# #[graphql_object(context = Database)]
 # impl Query {
 #     fn hello_world() -> &str {
 #         "Hello World!"
@@ -114,7 +119,7 @@ where [`Connection`][Connection] is a `Stream` of values returned by the operati
 # 
 # type StringStream = Pin<Box<dyn Stream<Item = Result<String, FieldError>> + Send>>;
 # 
-# #[juniper::graphql_subscription(Context = Database)]
+# #[graphql_subscription(context = Database)]
 # impl Subscription {
 #     async fn hello_world() -> StringStream {
 #         let stream =
@@ -132,11 +137,9 @@ async fn run_subscription() {
     let schema = schema();
     let coordinator = Coordinator::new(schema);
     let req: GraphQLRequest<DefaultScalarValue> = serde_json::from_str(
-        r#"
-        {
+        r#"{
             "query": "subscription { helloWorld }"
-        }
-    "#,
+        }"#,
     )
         .unwrap();
     let ctx = Database::new();
@@ -145,7 +148,7 @@ async fn run_subscription() {
         println!("{}", serde_json::to_string(&result).unwrap());
     }
 }
-
+#
 # fn main() { }
 ```     
 

docs/book/content/quickstart.md

@@ -28,24 +28,28 @@ resolvers, which you will use for the `Query` and `Mutation` roots.
 ```rust
 # #![allow(unused_variables)]
 # extern crate juniper;
-use juniper::{FieldResult, EmptySubscription};
-
+# use std::fmt::Display;
+use juniper::{
+    graphql_object, EmptySubscription, FieldResult, GraphQLEnum, 
+    GraphQLInputObject, GraphQLObject, ScalarValue,
+};
+#
 # struct DatabasePool;
 # impl DatabasePool {
 #     fn get_connection(&self) -> FieldResult<DatabasePool> { Ok(DatabasePool) }
 #     fn find_human(&self, _id: &str) -> FieldResult<Human> { Err("")? }
 #     fn insert_human(&self, _human: &NewHuman) -> FieldResult<Human> { Err("")? }
 # }
 
-#[derive(juniper::GraphQLEnum)]
+#[derive(GraphQLEnum)]
 enum Episode {
     NewHope,
     Empire,
     Jedi,
 }
 
-#[derive(juniper::GraphQLObject)]
-#[graphql(description="A humanoid creature in the Star Wars universe")]
+#[derive(GraphQLObject)]
+#[graphql(description = "A humanoid creature in the Star Wars universe")]
 struct Human {
     id: String,
     name: String,
@@ -55,8 +59,8 @@ struct Human {
 
 // There is also a custom derive for mapping GraphQL input objects.
 
-#[derive(juniper::GraphQLInputObject)]
-#[graphql(description="A humanoid creature in the Star Wars universe")]
+#[derive(GraphQLInputObject)]
+#[graphql(description = "A humanoid creature in the Star Wars universe")]
 struct NewHuman {
     name: String,
     appears_in: Vec<Episode>,
@@ -78,14 +82,13 @@ impl juniper::Context for Context {}
 
 struct Query;
 
-#[juniper::graphql_object(
+#[graphql_object(
     // Here we specify the context type for the object.
     // We need to do this in every type that
     // needs access to the context.
-    Context = Context,
+    context = Context,
 )]
 impl Query {
-
     fn apiVersion() -> &str {
         "1.0"
     }
@@ -109,22 +112,26 @@ impl Query {
 
 struct Mutation;
 
-#[juniper::graphql_object(
-    Context = Context,
-)]
-impl Mutation {
+#[graphql_object(
+    context = Context,
 
-    fn createHuman(context: &Context, new_human: NewHuman) -> FieldResult<Human> {
-        let db = context.pool.get_connection()?;
-        let human: Human = db.insert_human(&new_human)?;
+    // If we need to use `ScalarValue` parametrization explicitly somewhere
+    // in the object definition (like here in `FieldResult`), we should
+    // declare an explicit type parameter for that, and specify it.
+    scalar = S,
+)]
+impl<S: ScalarValue + Display> Mutation {
+    fn createHuman(context: &Context, new_human: NewHuman) -> FieldResult<Human, S> {
+        let db = context.pool.get_connection().map_err(|e| e.map_scalar_value())?;
+        let human: Human = db.insert_human(&new_human).map_err(|e| e.map_scalar_value())?;
         Ok(human)
     }
 }
 
 // A root schema consists of a query, a mutation, and a subscription.
 // Request queries can be executed against a RootNode.
 type Schema = juniper::RootNode<'static, Query, Mutation, EmptySubscription<Context>>;
-
+#
 # fn main() {
 #   let _ = Schema::new(Query, Mutation{}, EmptySubscription::new());
 # }
@@ -143,10 +150,12 @@ You can invoke `juniper::execute` directly to run a GraphQL query:
 ```rust
 # // Only needed due to 2018 edition because the macro is not accessible.
 # #[macro_use] extern crate juniper;
-use juniper::{FieldResult, Variables, EmptyMutation, EmptySubscription};
-
+use juniper::{
+    graphql_object, EmptyMutation, EmptySubscription, FieldResult, 
+    GraphQLEnum, Variables,
+};
 
-#[derive(juniper::GraphQLEnum, Clone, Copy)]
+#[derive(GraphQLEnum, Clone, Copy)]
 enum Episode {
     NewHope,
     Empire,
@@ -160,16 +169,13 @@ impl juniper::Context for Ctx {}
 
 struct Query;
 
-#[juniper::graphql_object(
-    Context = Ctx,
-)]
+#[graphql_object(context = Ctx)]
 impl Query {
     fn favoriteEpisode(context: &Ctx) -> FieldResult<Episode> {
         Ok(context.0)
     }
 }
 
-
 // A root schema consists of a query, a mutation, and a subscription.
 // Request queries can be executed against a RootNode.
 type Schema = juniper::RootNode<'static, Query, EmptyMutation<Ctx>, EmptySubscription<Ctx>>;

docs/book/content/schema/schemas_and_mutations.md

@@ -24,18 +24,18 @@ object in Juniper, most commonly using the `graphql_object` proc macro:
 ```rust
 # #![allow(unused_variables)]
 # extern crate juniper;
-# use juniper::FieldResult;
-# #[derive(juniper::GraphQLObject)] struct User { name: String }
+# use juniper::{graphql_object, FieldResult, GraphQLObject};
+# #[derive(GraphQLObject)] struct User { name: String }
 struct Root;
 
-#[juniper::graphql_object]
+#[graphql_object]
 impl Root {
     fn userWithUsername(username: String) -> FieldResult<Option<User>> {
         // Look up user in database...
-# unimplemented!()
+#       unimplemented!()
     }
 }
-
+#
 # fn main() { }
 ```
 
@@ -47,18 +47,18 @@ that performs some mutating side-effect such as updating a database.
 ```rust
 # #![allow(unused_variables)]
 # extern crate juniper;
-# use juniper::FieldResult;
-# #[derive(juniper::GraphQLObject)] struct User { name: String }
+# use juniper::{graphql_object, FieldResult, GraphQLObject};
+# #[derive(GraphQLObject)] struct User { name: String }
 struct Mutations;
 
-#[juniper::graphql_object]
+#[graphql_object]
 impl Mutations {
     fn signUpUser(name: String, email: String) -> FieldResult<User> {
         // Validate inputs and save user in database...
-# unimplemented!()
+#       unimplemented!()
     }
 }
-
+#
 # fn main() { }
 ```
 
@@ -68,11 +68,13 @@ Many tools in the GraphQL ecosystem require the schema to be defined in the [Gra
 
 ```rust
 # extern crate juniper;
-use juniper::{FieldResult, EmptyMutation, EmptySubscription, RootNode};
+use juniper::{
+    graphql_object, EmptyMutation, EmptySubscription, FieldResult, RootNode,
+};
 
 struct Query;
 
-#[juniper::graphql_object]
+#[graphql_object]
 impl Query {
     fn hello(&self) -> FieldResult<&str> {
         Ok("hello world")