feat(core) add error message to improve DX (get vs resolve)

Author: kamilmysliwiec

integration/injector/e2e/scoped-instances.spec.ts

@@ -1,3 +1,4 @@
+import { InvalidClassScopeException } from '@nestjs/core/errors/exceptions/invalid-class-scope.exception';
 import { Test, TestingModule } from '@nestjs/testing';
 import { expect } from 'chai';
 import { ScopedController } from '../src/scoped/scoped.controller';
@@ -42,4 +43,12 @@ describe('Scoped Instances', () => {
     expect(request2).to.be.instanceOf(ScopedController);
     expect(request3).to.not.be.equal(request2);
   });
+
+  it('should throw an exception when "get()" method is used', async () => {
+    try {
+      testingModule.get(ScopedController);
+    } catch (err) {
+      expect(err).to.be.instanceOf(InvalidClassScopeException);
+    }
+  });
 });

packages/core/errors/exceptions/invalid-class-scope.exception.ts

@@ -0,0 +1,15 @@
+import { Abstract, Type } from '@nestjs/common/interfaces';
+import { isFunction } from '@nestjs/common/utils/shared.utils';
+import { INVALID_CLASS_SCOPE_MESSAGE } from '../messages';
+import { RuntimeException } from './runtime.exception';
+
+export class InvalidClassScopeException extends RuntimeException {
+  constructor(metatypeOrToken: Type<any> | Abstract<any> | string | symbol) {
+    let name = isFunction(metatypeOrToken)
+      ? (metatypeOrToken as Function).name
+      : metatypeOrToken;
+    name = name && name.toString();
+
+    super(INVALID_CLASS_SCOPE_MESSAGE`${name}`);
+  }
+}

packages/core/errors/messages.ts

@@ -81,6 +81,13 @@ export const UNKNOWN_EXPORT_MESSAGE = (
 export const INVALID_CLASS_MESSAGE = (text: TemplateStringsArray, value: any) =>
   `ModuleRef cannot instantiate class (${value} is not constructable).`;
 
+export const INVALID_CLASS_SCOPE_MESSAGE = (
+  text: TemplateStringsArray,
+  name: string | undefined,
+) =>
+  `${name ||
+    'This class'} is marked as a scoped provider. Request and transient-scoped providers can't be used in combination with "get()" method. Please, use "resolve()" instead.`;
+
 export const INVALID_MIDDLEWARE_CONFIGURATION = `An invalid middleware configuration has been passed inside the module 'configure()' method.`;
 export const UNKNOWN_REQUEST_MAPPING = `An invalid controller has been detected. Perhaps, one of your controllers is missing @Controller() decorator.`;
 export const UNHANDLED_RUNTIME_EXCEPTION = `Unhandled Runtime Exception.`;

packages/core/injector/container-scanner.ts

@@ -1,6 +1,7 @@
 import { Type } from '@nestjs/common';
-import { Abstract } from '@nestjs/common/interfaces';
+import { Abstract, Scope } from '@nestjs/common/interfaces';
 import { isFunction } from '@nestjs/common/utils/shared.utils';
+import { InvalidClassScopeException } from '../errors/exceptions/invalid-class-scope.exception';
 import { UnknownElementException } from '../errors/exceptions/unknown-element.exception';
 import { NestContainer } from './container';
 import { InstanceWrapper } from './instance-wrapper';
@@ -41,6 +42,12 @@ export class ContainerScanner {
       metatypeOrToken,
       contextModule,
     );
+    if (
+      instanceWrapper.scope === Scope.REQUEST ||
+      instanceWrapper.scope === Scope.TRANSIENT
+    ) {
+      throw new InvalidClassScopeException(metatypeOrToken);
+    }
     return instanceWrapper.instance;
   }