Net Core - 無法解決依賴關系

Question

我正在使用 GraphQL 2.4.0 和 .NET Core 3.1 解決方案和 Microsoft DI。 在突變內部，我需要執行額外的處理（如下面的 MyMutation class 所示）。

我的Schema.cs看起來像：

public class MySchema : GraphQL.Types.Schema
{
    private ISchema _schema { get; set; }
    public ISchema GraphQLSchema
    {
        get
        {
            return this._schema;
        }
    }

    public MySchema()
    {
        this._schema = Schema.For(@"
            type MyObj{
                id: ID
                name: String,
                type: String,
                createdAt: String
            }

            type Mutation {
                objSync(type: String): MyObj
            }

            type Query {
                myobj: MyObj
            }
        ", _ =>
        {
            _.Types.Include<MyQuery>();
            _.Types.Include<MyMutation>();
        });
    }
}

MyMutation.cs看起來像：

[GraphQLMetadata("MyMutation")]
public class MyMutation
{
    private readonly ISomeType someType;

    public MyMutation(ISomeType someType)
    {
        this.someType= someType;
    }

    [GraphQLMetadata("objSync")]
    public Document SyncObj(string type)
    {
        byte[] _bytes = null;
        _bytes = someType.Process(type).Result;
        return new Obj { File = Encoding.UTF8.GetString(_bytes , 0, _bytes .Length) };
    }
}

ISomeType看起來像：

public interface ISomeType
{
    Task<byte[]> Process(string type);
}

SomeManager.cs將是：

public class SomeManager: ISomeType
{
    private readonly IConfiguration configuration;
    private readonly Func<string, IOtherTypeManager> otherType;

    public SomeManager(IConfiguration configuration, Func<string, IOtherTypeManager> otherType)
    {
        this.configuration = configuration;
        this.otherType= otherType;
    }

    public async Task<byte[]> Process(string type)
    {
       ...
    }
}

您可能會注意到，我需要使用 DI 解析 ISomeType。 所以Startup.cs看起來像：

...
public static void AddServices(this IServiceCollection services)
    {
        services.AddSingleton<IDependencyResolver>(_ => new FuncDependencyResolver(_.GetRequiredService));
        services.AddSingleton<IDocumentExecuter, DocumentExecuter>();
        services.AddSingleton<IDocumentWriter, DocumentWriter>();
        services.AddSingleton<ISomeType, SomeManager>();
        ...
    }
...

當執行程序時，它會拋出以下異常：

Error trying to resolve objSync.
Failed to call Activator.CreateInstance. Type: MyNameSpace.Graphql.MyMutation

No parameterless constructor defined for type 'MyNameSpace.Graphql.MyMutation'.

at System.RuntimeType.CreateInstanceDefaultCtorSlow(Boolean publicOnly, Boolean wrapExceptions, Boolean fillCache)
at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, Boolean wrapExceptions)
at System.Activator.CreateInstance(Type type, Boolean nonPublic, Boolean wrapExceptions)
at System.Activator.CreateInstance(Type type)
at GraphQL.DefaultDependencyResolver.Resolve(Type type)

我需要以不同的方式解析ISomeType嗎？ 請指導。

更新

從MyMutation.cs ISomeType了這個問題......但我需要它來調用someType.Process(type).Result 。

Answer 1

MyMutation class 也需要在 DI 容器中注冊。 你能試試這個嗎？

services.AddSingleton<MyMutation>();

Answer 2

services.AddScoped<MyMutation>();
services.AddScoped<ISchema, MySchema>();

基本上我會遵循這個例子： https://github.com/graphql-dotnet/examples/tree/master/src/StarWars