typeORM

介绍

1. TypeORM 是一个 ORM(object-relational mapping)框架,可以在能执行 js 或者 ts 的环境中使用
2. 设计目标：让你可以用最少的 js 代码，完成各种数据库操作
3. TypeORM 同时支持 Active Record 模式和 Data Mapper 模式

介绍 Active Record 和 Data Mapper

1. active record

   • 具体概念建议百度
   • 通过模型访问数据库，在模型中定义所有的查询方法
   • 需要继承 BaseEntity

2. Data Mapper

   • 数据模型只定义属性，不提供数据库操作
   • 不需要继承 BaseEntity
   • 自己定义单独的 class，一般称为“repositories”

3. 举个栗子，假设你有一个用户 model，你想根据 firstName+lastName 查询一个人

   • Active Record 模式

   import { BaseEntity, Entity, PrimaryGeneratedColumn, Column } from "typeorm";
   
   @Entity()
   export class User extends BaseEntity {
     @PrimaryGeneratedColumn()
     id: number;
   
     @Column()
     firstName: string;
   
     @Column()
     lastName: string;
   
     @Column()
     isActive: boolean;
   
     static findByName(firstName: string, lastName: string) {
       return this.createQueryBuilder("user")
         .where("user.firstName = :firstName", { firstName })
         .andWhere("user.lastName = :lastName", { lastName })
         .getMany();
     }
   }
   
   // 查询
   const timber = await User.findByName("Timber", "Saw");

   • data mapping 模式

   import { Entity, PrimaryGeneratedColumn, Column } from "typeorm";
   
   @Entity()
   export class User {
     @PrimaryGeneratedColumn()
     id: number;
   
     @Column()
     firstName: string;
   
     @Column()
     lastName: string;
   
     @Column()
     isActive: boolean;
   }
   
   // 查询
   const timber = await userRepository.findOneBy({
     firstName: "Timber",
     lastName: "Saw",
   });

关联关系

options

• eager: boolean, 设置为 true 时，当主 entity 查询时，会返回关联数据
• cascade: boolean | (“insert” | “update”)[] , 新增或者更新 entity 时，会同步保存关联关系
• onDelete: “RESTRICT”|”CASCADE”|”SET NULL”, 定义删除时，外健对应的行为
• nullable: boolean，关联关系是否允许为空
• orphanedRowAction: “nullify” | “delete” | “soft-delete”, 删除子数据时，子数据的存储方式

JoinColumn

• 在当前表中加列名

• options

  • name：指定关联关系列名，默认是 id
  • referencedColumnName，指定关联表里的列名

  @ManyToOne(type => Category)
  @JoinColumn([
      { name: "category_id", referencedColumnName: "id" },
      { name: "locale_id", referencedColumnName: "locale_id" }
  ])
  category: Category;

JoinTable

• 用在 many-to-many 中，创建关联关系表

• options

  • name，tableName

  • joinColumn

    • name
    • referencedColumnName

  • inverseJoinColumn

    • name
    • referencedColumnName

    @ManyToMany(type => Category)
    @JoinTable({
        name: "question_categories", // table name for the junction table of this relation
        joinColumn: {
            name: "question",
            referencedColumnName: "id"
        },
        inverseJoinColumn: {
            name: "category",
            referencedColumnName: "id"
        }
    })
    categories: Category[];

one-to-one

• 需要使用 JoinColumn，指定关联关系

  import { Entity, PrimaryGeneratedColumn, Column } from "typeorm";
  
  @Entity()
  export class Profile {
    @PrimaryGeneratedColumn()
    id: number;
  
    @Column()
    gender: string;
  
    @Column()
    photo: string;
  }
  
  import {
    Entity,
    PrimaryGeneratedColumn,
    Column,
    OneToOne,
    JoinColumn,
  } from "typeorm";
  import { Profile } from "./Profile";
  
  @Entity()
  export class User {
    @PrimaryGeneratedColumn()
    id: number;
  
    @Column()
    name: string;
  
    @OneToOne(() => Profile)
    @JoinColumn()
    profile: Profile;
  }

Many-to-one / one-to-many

• 可以省略 JoinColumn，会自动在 many-to-one entity 中保存关联关系

  import { Entity, PrimaryGeneratedColumn, Column, ManyToOne } from "typeorm";
  import { User } from "./User";
  
  @Entity()
  export class Photo {
    @PrimaryGeneratedColumn()
    id: number;
  
    @Column()
    url: string;
  
    @ManyToOne(() => User, (user) => user.photos)
    user: User;
  }
  import { Entity, PrimaryGeneratedColumn, Column, OneToMany } from "typeorm";
  import { Photo } from "./Photo";
  
  @Entity()
  export class User {
    @PrimaryGeneratedColumn()
    id: number;
  
    @Column()
    name: string;
  
    @OneToMany(() => Photo, (photo) => photo.user)
    photos: Photo[];
  }

many-to-many

• 需要使用 JoinTable 指定关联关系

  import { Entity, PrimaryGeneratedColumn, Column } from "typeorm";
  
  @Entity()
  export class Category {
    @PrimaryGeneratedColumn()
    id: number;
  
    @Column()
    name: string;
  }
  
  import {
    Entity,
    PrimaryGeneratedColumn,
    Column,
    ManyToMany,
    JoinTable,
  } from "typeorm";
  import { Category } from "./Category";
  
  @Entity()
  export class Question {
    @PrimaryGeneratedColumn()
    id: number;
  
    @Column()
    title: string;
  
    @Column()
    text: string;
  
    @ManyToMany(() => Category)
    @JoinTable()
    categories: Category[];
  }

Enabling logging

• 打印 sql 日志

  {
      name: "mysql",
      type: "mysql",
      host: "localhost",
      port: 3306,
      username: "test",
      password: "test",
      database: "test",
      logging: true
  }

相关链接

官方文档
gitBook