GraphQL教程(二) .net Core api 2.1

一、编辑Schema文件夹内容

真正的GraphQL教程才刚刚开始QWQ，怕了吧，Schema的文件夹才是关于Graph的

置于GraphQL是什么,一种用于 API 的查询语言

GraphQL 既是一种用于 API 的查询语言也是一个满足你数据查询的运行时。 GraphQL 对你的 API 中的数据提供了一套易于理解的完整描述，使得客户端能够准确地获得它需要的数据，而且没有任何冗余，也让 API 更容易地随着时间推移而演进，还能用于构建强大的开发者工具。

官网：https://graphql.cn/

据我所知的是GraphQL由facebook所制造，现阶段github等一群大佬企业也在用这个

在类库schema文件夹中添加三个类MovieType,ActorType,MovieRatingEnum
其中MovieRatingEnum是枚举类型，其他的你可以一一对应下
代码看不看的懂，看不懂就对了，不然你也不用学了，直接抄吧，抄个一两遍就有感悟了，到时候再去官网逛逛提升下自己

首先编写MovieRatingEnum类，直接上代码

using GraphQL.Types;
using GraphStudy.Movies.Movies;

namespace GraphStudy.Movies.Schema
{
    public class MovieRatingEnum:EnumerationGraphType<MovieRatingEnum>
    {
        //先定义下构造函数,列表枚举的GraphQL
        public MovieRatingEnum()
        {
            Name = "MovieRating";//类型的名字
            Description = "";//类型的描述

            //将鼠标置于AddValue上显示name,description,value,[deprecationReason]  []的含义是可填可不填的意思
            AddValue(MovieRating.Unrated.ToString(), "Unrated",MovieRating.Unrated);
            AddValue(MovieRating.G.ToString(), "G", MovieRating.G);
            AddValue(MovieRating.PG.ToString(), "PG", MovieRating.PG);
            AddValue(MovieRating.PG13.ToString(), "PG13", MovieRating.PG13);
            AddValue(MovieRating.R.ToString(), "R", MovieRating.R);
            AddValue(MovieRating.NC17.ToString(), "NC17", MovieRating.NC17);
        }
    }
}

编写ActorType类，直接上代码

using GraphQL.Types;
using GraphStudy.Movies.Movies;

namespace GraphStudy.Movies.Schema
{
    public class ActorType:ObjectGraphType<Actor>
    {
        public ActorType()
        {
            Field(x => x.Id);
            Field(x => x.Name);
        }
    }
}

编写MovieType类

using GraphQL.Types;
using GraphStudy.Movies.Movies;
using GraphStudy.Movies.Services;

namespace GraphStudy.Movies.Schema
{
    public class MovieType:ObjectGraphType<Movie>
    {
        //先定义下构造函数
        public MovieType(IActorService actorService)
        {
            Name = "Movie";//类型的名字
            Description = "";//类型的描述

            Field(x => x.Id);
            Field(x => x.Name);
            Field(x => x.Company);
            Field(x => x.ReleaseDate);
            Field(x => x.ActorId);

            //将枚举的Graph也加入其中,这是在查询Movie中嵌套（学过sql应该懂得嵌套查询）一个MovieRatingEnum
            //取名movieRating，查询结果context.Source.MovieRating
            Field<MovieRatingEnum>("movieRating", resolve: context => context.Source.MovieRating);

            Field<ActorType>("Actor", resolve: context => actorService.GetByIdAsync(context.Source.ActorId));

            //做一个小小的测试
            Field<StringGraphType>("customString", resolve: context => "1234");
        }
    }
}

在Schema文件夹中进行添加查询类MoviesQuery

using GraphQL.Types;
using GraphStudy.Movies.Services;

namespace GraphStudy.Movies.Schema
{
    //查询
    class MoviesQuery:ObjectGraphType
    {
        public MoviesQuery(IMovieService movieService)
        {
            Name = "Query";

            //查询所有Movie
            Field<ListGraphType<MovieType>>("movies", resolve: context => movieService.GetAsyncs());
        }
    }
}

在Service文件夹内添加MovieSchema类，以后的增删改查都在此添加服务

using GraphQL;

namespace GraphStudy.Movies.Schema
{
    class MovieSchema:GraphQL.Types.Schema
    {
        public MovieSchema(IDependencyResolver dependencyResolver, MoviesQuery moviesQuery)
        {
            DependencyResolver = dependencyResolver;
            Query = moviesQuery;
        }
    }
}

在startup添加服务

services.AddSingleton<ActorType>();
            services.AddSingleton<MovieRatingEnum>();
            services.AddSingleton<MovieType>();
            services.AddSingleton<MoviesQuery>();
            services.AddSingleton<MovieSchema>();

            services.AddSingleton<IDependencyResolver>(s => new FuncDependencyResolver(s.GetRequiredService));

2.调用GraphQL 的UI界面

进入GraphQL的github
https://github.com/graphql-dotnet

找到这个

GraphStudy.Api在NuGet程序包添加这三个包
GraphQL.Server.Transports.AspNetCore
GraphQL.Server.Transports.WebSockets
GraphQL.Server.Ui.Playground

将途中的复制下来

startup全部代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using GraphQL;
using GraphQL.Server;
using GraphQL.Server.Ui.Playground;
using GraphStudy.Movies.Schema;
using GraphStudy.Movies.Services;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;


namespace GraphStudy.Api
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddSingleton<IMovieService, MovieService>();
            services.AddSingleton<IActorService, ActorService>();

            services.AddSingleton<ActorType>();
            services.AddSingleton<MovieRatingEnum>();
            services.AddSingleton<MovieType>();
            services.AddSingleton<MoviesQuery>();
            services.AddSingleton<MovieSchema>();

            services.AddSingleton<IDependencyResolver>(s => new FuncDependencyResolver(s.GetRequiredService));


            // Add GraphQL services and configure options
            services.AddGraphQL(options =>
                {
                    options.EnableMetrics = true;
                    options.ExposeExceptions = true;//是否包容异常，改下
                })
                .AddWebSockets() // Add required services for web socket support
                .AddDataLoader(); // Add required services for DataLoader support
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            // this is required for websockets support
            app.UseWebSockets();

            // use websocket middleware for ChatSchema at path /graphql
            app.UseGraphQLWebSockets<MovieSchema>("/graphql");

            // use HTTP middleware for ChatSchema at path /graphql
            app.UseGraphQL<MovieSchema>("/graphql");

            //去点另外两个UI，因为我们刚刚添加的包就是Playground，所以保留这个就行
            // use graphql-playground middleware at default url /ui/playground
            app.UseGraphQLPlayground(new GraphQLPlaygroundOptions());

        }
    }
}

运行成功
query{
movies{
id
name
company
movieRating
releaseDate
actorId
customString
}
}
是类似sql的查询语句，GraphQL独有
可参阅官方学习，或者以后教
https://github.com/1045683477/GraphQL-
这是到现在的写的,代码在GitHub上