fix: fix entityManager.getId for custom join table

getId currently returns undefined for an entity with composite primary
key if primary key columns also foreign keys with lazy relations,
for e.g., in a custom join table. This commit tries to fix that

Closes: typeorm#7736 (maybe)

src/metadata/ColumnMetadata.ts

@@ -570,7 +570,12 @@ export class ColumnMetadata {
             return Object.keys(map).length > 0 ? map : undefined;
 
         } else { // no embeds - no problems. Simply return column property name and its value of the entity
-            if (this.relationMetadata && entity[this.relationMetadata.propertyName] && entity[this.relationMetadata.propertyName] instanceof Object) {
+            /**
+             * Object.getOwnPropertyDescriptor checks if the relation is lazy, in which case value is a Promise
+             * DO NOT use `entity[this.relationMetadata.propertyName] instanceof Promise`, which will invoke property getter and make unwanted DB request
+             * refer: https://github.com/typeorm/typeorm/pull/8676#issuecomment-1049906331
+             */
+            if (this.relationMetadata && !Object.getOwnPropertyDescriptor(entity, this.relationMetadata.propertyName)?.get && entity[this.relationMetadata.propertyName] && entity[this.relationMetadata.propertyName] instanceof Object) {
                 const map = this.relationMetadata.joinColumns.reduce((map, joinColumn) => {
                     const value = joinColumn.referencedColumn!.getEntityValueMap(entity[this.relationMetadata!.propertyName]);
                     if (value === undefined) return map;

test/other-issues/get-id-for-composite-primary-key/entity/Category.ts

@@ -0,0 +1,10 @@
+import { Column, Entity, PrimaryGeneratedColumn } from "../../../../src";
+
+@Entity()
+export class Category {
+    @PrimaryGeneratedColumn("increment")
+    id!: number;
+
+    @Column()
+    name!: string;
+}

test/other-issues/get-id-for-composite-primary-key/entity/Post.ts

@@ -0,0 +1,10 @@
+import { Column, Entity, PrimaryGeneratedColumn } from "../../../../src";
+
+@Entity()
+export class Post {
+    @PrimaryGeneratedColumn("increment")
+    id!: number;
+
+    @Column()
+    content!: string;
+}

test/other-issues/get-id-for-composite-primary-key/entity/PostCategory.ts

@@ -0,0 +1,24 @@
+import {
+    CreateDateColumn,
+    Entity,
+    ManyToOne,
+    PrimaryColumn,
+} from "../../../../src";
+import { Category } from "./Category";
+import { Post } from "./Post";
+
+@Entity()
+export class PostCategory {
+    @ManyToOne(() => Post)
+    post!: Promise<Post>;
+    @PrimaryColumn()
+    postId!: Post["id"];
+
+    @ManyToOne(() => Category)
+    category!: Promise<Category>;
+    @PrimaryColumn()
+    categoryId!: Category["id"];
+
+    @CreateDateColumn()
+    added!: Date;
+}

test/other-issues/get-id-for-composite-primary-key/get-id-for-composite-primary-key.ts

@@ -0,0 +1,47 @@
+import { expect } from "chai";
+import "reflect-metadata";
+import { Connection } from "../../../src/connection/Connection";
+import {
+    closeTestingConnections,
+    createTestingConnections,
+    reloadTestingDatabases,
+} from "../../utils/test-utils";
+import { Category } from "./entity/Category";
+import { Post } from "./entity/Post";
+import { PostCategory } from "./entity/PostCategory";
+
+describe("other issues > getId should not return undefined for composite primary keys with lazy relations", () => {
+    let connections: Connection[];
+    before(
+        async () =>
+            (connections = await createTestingConnections({
+                entities: [__dirname + "/entity/*{.js,.ts}"],
+            }))
+    );
+    beforeEach(() => reloadTestingDatabases(connections));
+    after(() => closeTestingConnections(connections));
+
+    it("getId should not return undefined", () =>
+        Promise.all(
+            connections.map(async ({ manager }) => {
+                const post = manager.create(Post, {
+                    content: "Sample Post",
+                });
+                await manager.save(post);
+
+                const category = manager.create(Category, {
+                    name: "javascript",
+                });
+                await manager.save(category);
+
+                const postCategory = manager.create(PostCategory, {});
+                postCategory.post = Promise.resolve(post);
+                postCategory.category = Promise.resolve(category);
+                await manager.save(postCategory);
+
+                expect(manager.getId(post)).not.to.be.undefined;
+                expect(manager.getId(category)).not.to.be.undefined;
+                expect(manager.getId(postCategory)).not.to.be.undefined;
+            })
+        ));
+});