GraphQL案例演示

18-11-28 banq
         

TakeShape的联合创始人Andrew Sprouse在纽约的JAMstack聚会介绍了GraphQL。

什么是GraphQL?

模式定义+查询语言+解析框架

架构

  • 提供数据的强类型描述
  • 架构描述语言(SDL)是指定架构的推荐跨平台方式。

enum Title {
    ACTOR
    DIRECTOR
}

type Role {
    characterName: String!
    title: Title
    movie: Movie
}

type Person {
    name: String!
    photo: String
    filmography: [Role]
}

type Movie {
    title: String!
    watched: Boolean
    rating: Float
    poster: String
    actors: [Person]!
    director: Person!
    year: String
}

GraphQL Schema还指定了如何使用查询和突变与数据进行交互:

type Query {
    listMovies: [Movie]
}

type Mutation {
    addMove(title: String): [Movie]
    removeMovie(title: String): [Movie]
}

查询Langauge

查询您的数据并准确获取您需要的内容:

query {
    getToWatchList {
        watched
        movie {
            title
            year
            director
        }
    }
}

{
  "data": {
    "getToWatchList": [
      {
        "watched": true,
        "movie": {
          "title": "Top Gun",
          "year": "1985",
          "director": "Tony Scott"
        }
      },
      {
        "watched": true,
        "movie": {
          "title": "Big Trouble in Little China",
          "year": "1986",
          "director": "John Carpenter"
        }
      },
      {
        "watched": true,
        "movie": {
          "title": "The Princess Bride",
          "year": "1987",
          "director": "Rob Reiner"
        }
      },
      {
        "watched": false,
        "movie": {
          "title": "Taxi Driver",
          "year": "1976",
          "director": "Martin Scorsese"
        }
      }
    ]
  }
}

修改数据

mutation {
    addMovieToWatch(title: "Die Hard") {
        watched
        movieTitle
        movie {
            title
            year
            director
        }
    }
}

{
  "data": {
    "addMovieToWatch": [
      {
        "watched": false,
        "movie": {
          "title": "Taxi Driver",
          "year": "1976",
          "director": "Martin Scorsese"
        }
      },
      {
        "watched": false,
        "movie": {
          "title": "Die Hard",
          "year": "1988",
          "director": "John McTiernan"
        }
      }
    ]
  }
}

实现框架

  • 每个GraphQL实现都提供自己的查询解析框架
  • GraphQL.js是参考实现
  • 执行查询和变异解析

架构(SDL)

type Query {
    getToWatchList: [ToWatch]
}

type Mutation {
    addMovieToWatch(title: String!): [ToWatch]
    removeMovieToWatch(title: String!): [ToWatch]
    markMovieWatched(title: String! watched: Boolean!): [ToWatch]
}

解析器

const resolvers = {
    Query: {
        getToWatchList: () => {
            return WatchList.list();
        }
    },

    Mutation: {
        addMovieToWatch(_, {title}) {
            return WatchList.add(title);
        },

        removeMovieToWatch(_, {title}) {
            return WatchList.remove(title);
        },

        markMovieWatched(_, {title, watched}) {
            return WatchList.markWatched(title, watched);
        }
    }
};

解析器还能够解析动态计算字段

架构(SDL)

type Move {
    title: String
    rating: Float
    poster: String
    actors: String
    director: String 
    year: String
}

type ToWatch {
    movieTitle: String!
    movie: Movie
    watched: Boolean!
}

解析器

const resolvers = {
    ToWatch: {
        async movie(toWatch) {
            const info = await fetchMovieInfo(toWatch.movieTitle);
            return info ? {
                title: info.Title,
                rating: info.imdbRating,
                poster: info.Poster,
                year: info.Year,
                actors: info.Actors,
                director: info.Director
            } : null
        }
    }
};