Update Loader to use loader class types instead name strings

This is a requirement from Nest 8 change where classes are registered
by class instance instead of class name.
nestjs/nest#6141
nestjs/nest#5591

src/core/data-loader/data-loader.interceptor.ts

@@ -3,13 +3,14 @@ import {
   ExecutionContext,
   Injectable,
   NestInterceptor,
+  Type,
 } from '@nestjs/common';
 import { ContextIdFactory, ModuleRef } from '@nestjs/core';
 import { GqlContextType, GqlExecutionContext } from '@nestjs/graphql';
 import { Observable } from 'rxjs';
 import { ServerException } from '../../common';
 import { NEST_LOADER_CONTEXT_KEY } from './constants';
-import { NestDataLoader } from './loader.decorator';
+import { DataLoader, NestDataLoader } from './loader.decorator';
 
 @Injectable()
 export class DataLoaderInterceptor implements NestInterceptor {
@@ -25,26 +26,35 @@ export class DataLoaderInterceptor implements NestInterceptor {
     if (ctx[NEST_LOADER_CONTEXT_KEY] === undefined) {
       ctx[NEST_LOADER_CONTEXT_KEY] = {
         contextId: ContextIdFactory.create(),
-        getLoader: (type: string): Promise<NestDataLoader<any, any>> => {
-          if (ctx[type] === undefined) {
-            ctx[type] = (async () => {
-              try {
-                return (
-                  await this.moduleRef.resolve<NestDataLoader<any, any>>(
-                    type,
-                    ctx[NEST_LOADER_CONTEXT_KEY].contextId,
-                    { strict: false }
-                  )
-                ).generateDataLoader(ctx);
-              } catch (e) {
-                throw new ServerException(
-                  `The loader ${type} is not provided`,
-                  e
-                );
-              }
-            })();
+        loaders: new Map<
+          Type<NestDataLoader<any, any>>,
+          DataLoader<any, any>
+        >(),
+        getLoader: (
+          type: Type<NestDataLoader<any, any>>
+        ): Promise<NestDataLoader<any, any>> => {
+          if (!ctx[NEST_LOADER_CONTEXT_KEY].loaders.has(type)) {
+            ctx[NEST_LOADER_CONTEXT_KEY].loaders.set(
+              type,
+              (async () => {
+                try {
+                  return (
+                    await this.moduleRef.resolve<NestDataLoader<any, any>>(
+                      type,
+                      ctx[NEST_LOADER_CONTEXT_KEY].contextId,
+                      { strict: false }
+                    )
+                  ).generateDataLoader(ctx);
+                } catch (e) {
+                  throw new ServerException(
+                    `The loader ${type.name} is not provided`,
+                    e
+                  );
+                }
+              })()
+            );
           }
-          return ctx[type];
+          return ctx[NEST_LOADER_CONTEXT_KEY].loaders.get(type);
         },
       };
     }

src/core/data-loader/loader.decorator.ts

@@ -1,17 +1,12 @@
-import { createParamDecorator, ExecutionContext } from '@nestjs/common';
+import { createParamDecorator, ExecutionContext, Type } from '@nestjs/common';
 import { APP_INTERCEPTOR } from '@nestjs/core';
 import {
   GqlExecutionContext,
   GqlContextType as GqlRequestType,
 } from '@nestjs/graphql';
 // eslint-disable-next-line no-restricted-imports -- the one spot we do want to import it
 import * as DataLoaderLib from 'dataloader';
-import {
-  AbstractClassType,
-  GqlContextType,
-  ID,
-  ServerException,
-} from '../../common';
+import { GqlContextType, ID, ServerException } from '../../common';
 import { NEST_LOADER_CONTEXT_KEY } from './constants';
 import { DataLoaderInterceptor } from './data-loader.interceptor';
 
@@ -59,13 +54,7 @@ export interface NestDataLoader<T, Key = ID, CachedKey = Key> {
  * The decorator to be used within your graphql method.
  */
 export const Loader = createParamDecorator(
-  (data: AbstractClassType<any>, context: ExecutionContext) => {
-    let name = data?.name;
-    if (!name) {
-      throw new ServerException(`Invalid name provider to @Loader ('${name}')`);
-    }
-    name += 'Loader';
-
+  (type: Type<NestDataLoader<any, any>>, context: ExecutionContext) => {
     if (context.getType<GqlRequestType>() !== 'graphql') {
       throw new ServerException(
         '@Loader should only be used within the GraphQL context'
@@ -79,6 +68,6 @@ export const Loader = createParamDecorator(
       );
     }
 
-    return ctx[NEST_LOADER_CONTEXT_KEY].getLoader(name);
+    return ctx[NEST_LOADER_CONTEXT_KEY].getLoader(type);
   }
 );