foreign-keys - TypeORM:如何显式设置ForeignKey而没有用于加载关系的属性？

Question

我不想创建用于将关系加载到其中的属性(如所有示例所示)。我唯一需要做的就是拥有一个明确的外键属性，以便迁移能够在数据库中为其创建适当的约束。与我需要的装饰器最接近的装饰器是@RelationId，但它仍然需要存在关系类的属性。

为了清楚起见，让我们以文档中的示例为例:

@Entity()
export class Post {
    @ManyToOne(type => Category)
    category: Category;

    @RelationId((post: Post) => post.category) // it still requires the presence of the `category` proeprty
    categoryId: number;

}

我在这里不需要 category属性。我想拥有 categoryId属性，并将其标记为 Category.Id的外键。它看起来应该像这样:

@Entity()
export class Post {

    @ForeignKey((category: Category) => category.Id) // it's a foreign key to Category.Id
    categoryId: number;

}

是否可以？

Answer 1

也许您可以创建和编写自己的迁移并像这样使用它:

    const queryRunner = connection.createQueryRunner();
    await queryRunner.createTable(new Table({
        name: "question",
        columns: [
            {
                name: "id",
                type: "int",
                isPrimary: true
            },
            {
                name: "name",
                type: "varchar",
            }
        ]
    }), true);

    await queryRunner.createTable(new Table({
        name: "answer",
        columns: [
            {
                name: "id",
                type: "int",
                isPrimary: true
            },
            {
                name: "name",
                type: "varchar",
            },
            {
                name: "questionId",
                isUnique: connection.driver instanceof CockroachDriver, // CockroachDB requires UNIQUE constraints on referenced columns
                type: "int",
            }
        ]
    }), true);

    // clear sqls in memory to avoid removing tables when down queries executed.
    queryRunner.clearSqlMemory();

    const foreignKey = new TableForeignKey({
        columnNames: ["questionId"],
        referencedColumnNames: ["id"],
        referencedTableName: "question",
        onDelete: "CASCADE"
    });
    await queryRunner.createForeignKey("answer", foreignKey);

该代码段是从orm类型的 functional test中提取的，您可以使用它在我认为的数据库上创建自己的约束。