router

README

AppSync Router

Wrapper for routing AppSync resolvers with AWS Lambda using Go.

Usage

Installation

$ > go get github.com/sbstjn/appsync-router

Routing

import (
  "github.com/sbstjn/appsync-router"
)

type ParamsRouteA struct {
	Foo string `json:"foo"`
}

type ParamsRouteB struct {
	Bar string `json:"bar"`
}

func handleRouteA(args ParamsRouteA) (interface{}, error) {
	return nil, fmt.Errorf("Nothing here in route A: %s", args.Foo)
}

func handleRouteB(args ParamsRouteB) (interface{}, error) {
	return nil, fmt.Errorf("Nothing here in route B: %s", args.Bar)
}

var (
	r = router.New()
)

func init() {
	r.Add("fieldA", handleRouteA)
	r.Add("fieldB", handleRouteB)
}

func main() {
	lambda.Start(r.Serve)
}

AppSync Configuration

Routing is based on a field property in your RequestMappingTemplate, which can be configured using the AWS Console or CloudFormation as well.

  AppSyncDataSource:
    Type: AWS::AppSync::DataSource
    Properties:
      ApiId: !GetAtt [ AppSyncAPI, ApiId ]
      Name: resolver
      Type: AWS_LAMBDA
      LambdaConfig:
        LambdaFunctionArn: !GetAtt [ Lambda, Arn ]
      ServiceRoleArn: !GetAtt [ Role, Arn ]

  AppSyncResolverA:
    Type: AWS::AppSync::Resolver
    Properties:
      ApiId: !GetAtt [ AppSyncAPI, ApiId ]
      TypeName: Query
      FieldName: fieldA
      DataSourceName: !GetAtt [ AppSyncDataSource, Name ]
      RequestMappingTemplate: '{ "version" : "2017-02-28", "operation": "Invoke", "payload": { "field": "fieldA", "arguments": $utils.toJson($context.arguments) } }'
      ResponseMappingTemplate: $util.toJson($context.result)

  AppSyncResolverB:
    Type: AWS::AppSync::Resolver
    Properties:
      ApiId: !GetAtt [ AppSyncAPI, ApiId ]
      TypeName: Query
      FieldName: fieldB
      DataSourceName: !GetAtt [ AppSyncDataSource, Name ]
      RequestMappingTemplate: '{ "version" : "2017-02-28", "operation": "Invoke", "payload": { "field": "fieldB", "arguments": $utils.toJson($context.arguments) } }'
      ResponseMappingTemplate: $util.toJson($context.result)

See [appsync-router-example] for a full working example how to use appsync-router and [Amazon Serverless Application Model] to deploy a GraphQL API using AppSync.

License

Feel free to use the code, it's released using the MIT license.

Contribution

You are welcome to contribute to this project! 😘

To make sure you have a pleasant experience, please read the code of conduct. It outlines core values and beliefs and will make working together a happier experience.

Documentation

Index

• type Handler
  • func (h *Handler) Call(args []reflect.Value) (interface{}, error)
  • func (h *Handler) Prepare(payload json.RawMessage) ([]reflect.Value, error)
• type Request
• type Router
  • func New() Router
  • func (r Router) Add(route string, function interface{}) error
  • func (r Router) Get(route string) (*Handler, error)
  • func (r Router) Serve(req Request) (interface{}, error)

Types

type Handler

type Handler struct {
	// contains filtered or unexported fields
}

Handler is an abstract function

func (*Handler) Call

func (h *Handler) Call(args []reflect.Value) (interface{}, error)

Call the handler and pass event

func (*Handler) Prepare

func (h *Handler) Prepare(payload json.RawMessage) ([]reflect.Value, error)

Prepare parses event payload

type Request

type Request struct {
	Field     string          `json:"field"`
	Arguments json.RawMessage `json:"arguments"`
}

Request stores all information from AppSync request

type Router

type Router map[string]Handler

Router stores all routes and handlers

func New

func New() Router

New returns a new Router

func (Router) Add

func (r Router) Add(route string, function interface{}) error

Add stores a new route with handler

func (Router) Get

func (r Router) Get(route string) (*Handler, error)

Get return handler for route or error

func (Router) Serve

func (r Router) Serve(req Request) (interface{}, error)

Serve parses the AppSync request