GraphQL案例演示

栏目: 前端 · 发布时间: 5年前

内容简介：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

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
        }
    }
}

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

修改数据

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

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

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

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

    Mutation: {
        addMovieToWatch(_, {title}) {
            <b>return</b> WatchList.add(title);
        },

        removeMovieToWatch(_, {title}) {
            <b>return</b> WatchList.remove(title);
        },

        markMovieWatched(_, {title, watched}) {
            <b>return</b> 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

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

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