本文共 8255 字，大约阅读时间需要 27 分钟。

首先要使用GraphQL安装三个包

GraphQLGraphQL.Server.Transports.AspNetCoreGraphQL.Server.Ui.Playground

定义基础类

public class Account{
       public Guid Id {
    get; set; }    public TypeOfAccount Type {
    get; set; }    public string Description {
    get; set; }    public Guid PersonId {
    get; set; }    public Person Person {
    get; set; }}public enum TypeOfAccount{
       Invalid,    Free,    Junior,    Intermediate}

public class Person{
       public Guid Id {
    get; set; }    public string Name {
    get; set; }    public string Address {
    get; set; }    public ICollection
   
     Accounts {
    get; set; }}
   

上下文

public class SampleContext{
       public List
   
     Persons {
    get; set; }    public List
    
      Accounts {
    get; set; }    public SampleContext()    {
           var ids = new[] {
    Guid.NewGuid(), Guid.NewGuid() };        Accounts = new List
     
              {
               new Account            {
                   Id = Guid.NewGuid(),                Type = TypeOfAccount.Junior,                Description = "初级会员",                PersonId = ids[0]            },            new Account            {
                   Id = Guid.NewGuid(),                Type = TypeOfAccount.Intermediate,                Description = "中级会员",                PersonId = ids[1]            },            new Account            {
                   Id = Guid.NewGuid(),                Type = TypeOfAccount.Free,                Description = "免费会员",                PersonId = ids[1]            }        };        Persons = new List
      
               {
               new Person            {
                   Id = ids[0],                Name = "张三",                Address = "北京"            },            new Person            {
                   Id = ids[1],                Name = "李四",                Address = "上海"            }        };    }}
      
     
    
   

仓储

public interface IAccountRepository{
       IEnumerable
   
     GetAllAccountsPerson(Guid personId);}public interface IPersonRepository{
       IEnumerable
    
      GetAll();    Person GetById(Guid id);}
    
   

public class AccountRepository : IAccountRepository{
       private readonly SampleContext _context;    public AccountRepository(SampleContext context)    {
           _context = context;    }    public IEnumerable
   
     GetAllAccountsPerson(Guid personId)    {
           return _context.Accounts.Where(a => a.PersonId == personId);    }}public class PersonRepository : IPersonRepository{
       private readonly SampleContext _context;    public PersonRepository(SampleContext context)    {
           _context = context;    }    public IEnumerable
    
      GetAll()    {
           return _context.Persons;    }    public Person GetById(Guid id)    {
           return _context.Persons.SingleOrDefault(p => p.Id == id);    }}
    
   

GraphQL相关类

public class AccountTypeEnumType : EnumerationGraphType
   
    {
       public AccountTypeEnumType()    {
           Name = "Type";    }}
   

public class AccountType : ObjectGraphType
   
    {
       public AccountType()    {
           Field(x => x.Id, type: typeof(IdGraphType));        Field(x => x.Description);        Field(x => x.PersonId, type: typeof(IdGraphType));        Field
    
     ("Type", "Account类型对象的枚举");    }}
    
   

public class PersonType : ObjectGraphType
   
    {
       public PersonType(IAccountRepository repository)    {
           Field(x => x.Id, type: typeof(IdGraphType));        Field(x => x.Name);        Field(x => x.Address);        Field
    
     
      >(            name: "accounts",            resolve: context => repository.GetAllAccountsPerson(context.Source.Id));    }}
     
    
   

public class AppSchema: Schema{
       public AppSchema(IDependencyResolver resolver)        :base(resolver)    {
           Query = resolver.Resolve
   
    ();    }}
   

public class AppQuery: ObjectGraphType{
       public AppQuery(IPersonRepository repository)    {
           Field
   
    
     >(            "persons",            resolve: context => repository.GetAll()        );        Field
     
      (            "person",            arguments: new QueryArguments(new QueryArgument
      
       
        > {
    Name = "personId" }),            resolve: context =>            {
                   var personId = context.GetArgument
        
         ("personId"); if (Guid.TryParse(personId, out var id)) return repository.GetById(id); context.Errors.Add(new ExecutionError("错误的GUID格式")); return null; } ); }}
        
       
      
     
    
   

在asp.net core中使用

public class Startup    {
           public void ConfigureServices(IServiceCollection services)        {
               services.AddControllers();            services.AddSingleton
   
    ();            services.AddScoped
    
     ();            services.AddScoped
     
      ();            services.AddScoped
      
       (s => new FuncDependencyResolver(s.GetRequiredService));            services.AddScoped
       
        ();             services.AddGraphQL(o => {
    o.ExposeExceptions = false; })                .AddGraphTypes(ServiceLifetime.Scoped);            services.Configure
        
         (options => { options.AllowSynchronousIO = true; }); } public void Configure(IApplicationBuilder app, IWebHostEnvironment env) { if (env.IsDevelopment()) { app.UseDeveloperExceptionPage(); } app.UseRouting(); app.UseAuthorization(); app.UseGraphQL
         
          (); app.UseGraphQLPlayground(options: new GraphQLPlaygroundOptions()); app.UseEndpoints(endpoints => { endpoints.MapControllers(); }); } }
         
        
       
      
     
    
   

用localhost:5000/ui/playgroud来查看服务页面

客户端的使用如下：

public class PersonConsumer{
       private readonly IGraphQLClient _client;    public PersonConsumer(IGraphQLClient client)    {
           _client = client;    }    public async Task
   
    
     > GetAll()    {
           var query = new GraphQLRequest        {
               Query = @"            query personsQuery{              persons {                id,                name,                address,                accounts {                  id,                  type,                  description                }              }            }"        };        var response = await _client.SendQueryAsync
     
      (query);        return response.Data.Persons;    }    public async Task
      
        Get(string id)    {
           var query = new GraphQLRequest        {
               Query = @"            query personQuery($personID: ID!) {              person(personId: $personID) {                id,                name,                address,                accounts {                  id,                  type,                  description                }              }            }",            Variables = new {
    personID = id }        };        var response = await _client.SendQueryAsync
       
        (query);        return response.Data.Person;    }}
       
      
     
    
   

[Route("api/[controller]")][ApiController]public class PersonController : ControllerBase{
       private readonly PersonConsumer _personConsumer;    public PersonController(PersonConsumer personConsumer)    {
           _personConsumer = personConsumer;    }    public async Task
   
     Get()    {
           var persons = await _personConsumer.GetAll();        return Ok(persons);    }    [HttpGet("{id}")]    public async Task
    
      Get(string id)    {
           var person = await _personConsumer.Get(id);        return Ok(person);    }}
    
   

public class Startup{
       public Startup(IConfiguration configuration)    {
           Configuration = configuration;    }    public IConfiguration Configuration {
    get; }    public void ConfigureServices(IServiceCollection services)    {
           services.AddScoped
   
    (s =>            new GraphQLHttpClient(Configuration["GraphQLUri"], new NewtonsoftJsonSerializer()));        services.AddScoped
    
     ();        services.AddControllers();    }    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)    {
           if (env.IsDevelopment())        {
               app.UseDeveloperExceptionPage();        }        app.UseRouting();        app.UseAuthorization();        app.UseEndpoints(endpoints =>        {
               endpoints.MapControllers();        });    }}
    
   

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