juniper/CHANGELOG.md

Change log

0.6.0 – Unreleased

TL;DR: Many big changes in how context types work and how they interact with the executor. Not too much to worry about if you're only using the macros and not deriving GraphQLType directly.

Breaking changes

• The executor argument in all resolver methods is now immutable. The executor instead uses interior mutability to store errors in a thread-safe manner.

  This change could open up for asynchronous or multi-threaded execution: you can today use something like rayon in your resolve methods to let child nodes be concurrently resolved.

  How to fix: All field resolvers that looked like field name(&mut executor now should say field name(&executor.

• The context type of GraphQLType is moved to an associated type; meaning it's no longer generic. This only affects people who implement the trait manually, not macro users.

  This greatly simplifies a lot of code by ensuring that there only can be one GraphQLType implementation for any given Rust type. However, it has the downside that support for generic contexts previously used in scalars, has been removed. Instead, use the new context conversion features to accomplish the same task.

  How to fix: Instead of impl GraphQLType<MyContext> for ..., you use impl GraphQLType for ... { type Context = MyContext;.

• All context types must derive the Context marker trait. This is part of an overarching change to allow different types to use different contexts.

  How to fix: If you have written e.g. graphql_object!(MyType: MyContext ...) you will need to add impl Context for MyContext {}. Simple as that.

• Registry and all meta type structs now takes one lifetime parameter, which affects GraphQLType's meta method. This only affects people who implement the trait manually.

  How to fix: Change the type signature of meta() to read fn meta<'r>(registry: &mut Registry<'r>) -> MetaType<'r>.

• The type builder methods on Registry no longer return functions taking types or fields. Due to how the borrow checker works with expressions, you will have to split up the instantiation into two statements. This only affects people who implement the GraphQLType trait manually.

  How to fix: Change the contents of your meta() methods to something like this:

  fn meta<'r>(registry: &mut Registry<r>) -> MetaType<'r> {
      let fields = &[ /* your fields ... */ ];
  
      registry.build_object_type::<Self>(fields).into_meta()
  }
  
  

Added

• Support for different contexts for different types. As GraphQL schemas tend to get large, narrowing down the context type to exactly what a given type needs is great for encapsulation. Similarly, letting different subsystems use different resources thorugh the context is also useful for the same reasons.

  Juniper supports two different methods of doing this, depending on your needs: if you have two contexts where one can be converted into the other without any extra knowledge, you can implement the new FromContext trait. This is useful if you have multiple crates or modules that all belong to the same GraphQL schema:

  
  struct TopContext {
    db: DatabaseConnection,
    session: WebSession,
    current_user: User,
  }
  
  struct ModuleOneContext {
    db: DatabaseConnection, // This module only requires a database connection
  }
  
  impl Context for TopContext {}
  impl Context for ModuleOneContext {}
  
  impl FromContext<TopContext> for ModuleOneContext {
    fn from(ctx: &TopContext) -> ModuleOneContext {
      ModuleOneContext {
        db: ctx.db.clone()
      }
    }
  }
  
  graphql_object!(Query: TopContext |&self| {
    field item(&executor) -> Item {
      executor.context().db.get_item()
    }
  });
  
  // The `Item` type uses another context type - conversion is automatic
  graphql_object!(Item: ModuleOneContext |&self| {
    // ...
  });
  
  

  The other way is to manually perform the conversion in a field resolver. This method is preferred when the child context needs extra knowledge than what exists in the parent context:

  
  // Each entity has its own context
  struct TopContext {
    entities: HashMap<i64, EntityContext>,
    db: DatabaseConnection,
  }
  
  struct EntityContext {
    // fields
  }
  
  impl Context for TopContext {}
  impl Context for EntityContext {}
  
  graphql_object!(Query: TopContext |&self| {
    // By returning a tuple (&Context, GraphQLType), you can tell the executor
    // to switch out the context for the returned value. You can wrap the
    // tuple in Option<>, FieldResult<>, FieldResult<Option<>>, or just return
    // the tuple without wrapping it.
    field entity(&executor, key: i64) -> Option<(&EntityContext, Entity)> {
      executor.context().entities.get(&key)
        .map(|ctx| (ctx, executor.context().db.get_entity(key)))
    }
  });
  
  graphql_object!(Entity: EntityContext |&self| {
    // ...
  });
  
  

Improvements

• Parser and query execution has now reduced the allocation overhead by reusing as much as possible from the query source and meta type information.

0.5.3 – 2016-12-05

Added

• jtry!: Helper macro to produce FieldResults from regular Results. Wherever you would be using try! in a regular function or method, you can use jtry! in a field resolver:

  graphql_object(MyType: Database |&self| {
    field count(&executor) -> FieldResult<i64> {
      let txn = jtry!(executor.context().transaction());
  
      let count = jtry!(txn.execute("SELECT COUNT(*) FROM user"));
  
      Ok(count[0][0])
    }
  });
  

Changes

• Relax context type trait requirements for the iron handler: your contexts no longer have to be Send + Sync.

• RootNode is now Send and Sync if both the mutation and query types implement Send and Sync.

Bugfixes

• return statements inside field resolvers no longer cause syntax errors.

0.5.2 – 2016-11-13

Added

• Support for marking fields and enum values deprecated.
• input_object! helper macro

Changes

• The included example server now uses the simple Star Wars schema used in query/introspection tests.

Bugfixes

• The query validators - particularly ones concerned with validation of input data and variables - have been improved significantly. A large number of test cases have been added.

• Macro syntax stability has also been improved. All syntactical edge cases of the macros have gotten tests to verify their correctness.