AWS AppSync 的基本语句

type Event {
    id: ID!
    name: String
    where: String
    when: String
    description: String
    # Paginate through all comments belonging to an individual post.
    comments(limit: Int, nextToken: String): CommentConnection
}

 AWS AppSync 是API的一种新标准；Schema是它的核心，SDL是Schema的主要语言。

schema {
    query: Query
    mutation: Mutation
    subscription: Subscription
}

1. query 查询语句：

type Query {
    # Get a single event by id.
    getEvent(id: ID!): Event
    # Paginate through events.
    listEvents(filter: TableEventFilterInput, limit: Int, nextToken: String): EventConnection
}

例子：

query{
  getEvent(id: "c16701cb-d614-4f21-b733-a636bc1c8437" ){
    description
    name
  }
}

返回 json:

{
  "data": {
    "getEvent": {
      "description": "test",
      "name": "landen"
    }
  }
}

　　2. mutation 

type Mutation {
    # Create a single event.
    createEvent(
        name: String!,
        when: String!,
        where: String!,
        description: String!
    ): Event
    # Delete a single event by id.
    deleteEvent(id: ID!): Event
    # Comment on an event.
    commentOnEvent(eventId: ID!, content: String!, createdAt: String!): Comment
}

• • createEvent 添加事件　　  

　　　　　　　　

mutation{
  createEvent(
    name: "landen",
    when: "2018-08-18",
    where: "guangdong",
    description: "today is rainny"
  ){
    id
    name
  }
}

返回 json:

{
  "data": {
    "getEvent": {
      "description": "test",
      "name": "landen"
    }
  }
}

• 　commentOnEvent 更改事件：
　　

mutation{
  commentOnEvent(
    eventId: "c16701cb-d614-4f21-b733-a636bc1c8437",
    content: "comment : rainny",
    createdAt: "today"
  ){
    eventId
  }
}

返回 json:

{
  "data": {
    "commentOnEvent": {
      "eventId": "c16701cb-d614-4f21-b733-a636bc1c8437"
    }
  }
}

• deleteEvent 删除事件：
  
  

mutation{
  deleteEvent(id: "c16701cb-d614-4f21-b733-a636bc1c8437"){
    name 
    description
  }
}

返回 json:

{
  "data": {
    "deleteEvent": {
      "name": "landen",
      "description": "test"
    }
  }
}

　　3.  subscription 订阅事件：

type Subscription {
    subscribeToEventComments(eventId: String!): Comment
        @aws_subscribe(mutations: ["commentOnEvent"])
}

subscription{
  subscribeToEventComments(eventId:"b5a25e27-8416-4486-8df1-27c185520074"){
    content
    @aws_subscribe(  mutations:["commentOnEvent"])
  }
  
}