Nest js无法解析依赖关系。在Auth服务中

Question

Nest无法解析AuthService（？）的依赖项。请验证[0]参数在当前上下文中是否可用。

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巢式验证测试

Error: Nest can't resolve dependencies of the AuthService (?). Please verify whether [0] argument is available in the current context.
    at Injector.lookupComponentInExports (/home/arpit/Documents/aquaapp/node_modules/@nestjs/core/injector/injector.js:129:19)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:182:7)
    at Function.Module.runMain (internal/modules/cjs/loader.js:697:11)
    at Object.<anonymous> (/home/arpit/Documents/aquaapp/node_modules/ts-node/src/_bin.ts:177:12)
    at Module._compile (internal/modules/cjs/loader.js:654:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:665:10)
    at Module.load (internal/modules/cjs/loader.js:566:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:506:12)
    at Function.Module._load (internal/modules/cjs/loader.js:498:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:695:10)
    at startup (internal/bootstrap/node.js:201:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:516:3)
 1: node::Abort() [/usr/bin/node]
 2: 0x8d04d9 [/usr/bin/node]
 3: v8::internal::FunctionCallbackArguments::Call(void (*)(v8::FunctionCallbackInfo<v8::Value> const&)) [/usr/bin/node]
 4: 0xb17d2c [/usr/bin/node]
 5: v8::internal::Builtin_HandleApiCall(int, v8::internal::Object**, v8::internal::Isolate*) [/usr/bin/node]
 6: 0x2176d1e042fd
Aborted (core dumped)

Answer 1

通常，当您收到这样的异常时，是因为您试图注入另一个模块的依赖项，而该依赖项尚未在exports数组中导出。这是一个示例：

假设您要在模块B中使用某些服务，请在模块A中使用：

@Injectable()
export class SampleService {}

@Module({
  exports: [SampleService]
})
export class ModuleA {}

@Module({
  imports: [ModuleA]
})
export class ModuleB {}

请记住，如果在ModuleB中导入ModuleA并在ModuleA中导入ModuleB，则会收到循环依赖项错误。希望对您有所帮助