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Chinese Readme
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README-zh_CN.md
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README-zh_CN.md
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TypeORM是一个优秀的Node.js ORM框架，采用TypeScript编写，支持使用TypeScript或Javascript(ES5, ES6, ES7)开发。
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目标是保持支持最新的Javascript特性来帮助开发各种用到数据库的应用 - 不管是轻应用还是企业级的。
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TypeORM可以做到：
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* 根据Models自动创建数据库Table
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* 可以透明的insert/update/delete数据库对象
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* 映射数据库table到javascript对象，映射table column到javascript对象属性
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* 提供表的一对一，多对一，一对多，多对多关系处理
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* 还有更多 ...
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不同于其他的JavaScript ORM，TypeORM使用的是数据映射模式，可以很轻松的创建出松耦合、可伸缩、可维护的应用。
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TypeORM可以帮助开发者专注于业务逻辑，而不用过于担心数据存储的问题。
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TypeORM参考了很多其他优秀ORM的实现, 比如 [Hibernate](http://hibernate.org/orm/), [Doctrine](http://www.doctrine-project.org/) 和 [Entity Framework](https://www.asp.net/entity-framework).
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## 安装
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1. 安装TypeORM:
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`npm install typeorm --save`
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2. 需要安装依赖模块 `reflect-metadata` :
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`npm install reflect-metadata --save`
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在应用里全局引用一下:
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* 比如在app.ts的入口处 `require("reflect-metadata")`
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3. 安装数据库驱动:
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* **MySQL** 或 **MariaDB**
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`npm install mysql --save`
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* **Postgres**
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`npm install pg --save`
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* **SQLite**
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`npm install sqlite3 --save`
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* **Microsoft SQL Server**
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`npm install mssql --save`
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* **Oracle** (experimental)
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`npm install oracledb --save`
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可以根据你的数据库选择安装上面的任意一个.
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使用oracle驱动需要参考安装说明：[地址](https://github.com/oracle/node-oracledb).
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#### TypeScript配置
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确保你的TypeScript编译器的版本大于**2.1**，并且在`tsconfig.json`开启下面设置:
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```json
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"emitDecoratorMetadata": true,
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"experimentalDecorators": true,
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```
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同时需要开启编译选项里的`lib`下的`es6`或者从`@typings`安装`es6-shim`
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#### Node.js 版本
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TypeORM在Node.JS 4.0或以上版本上测试通过。
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如果在应用启动过程中出错可以尝试升级node.js到最新版本。
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#### 在浏览器中使用WebSQL (试用)
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TypeORM可以在浏览器环境中工作，并且试验性的支持WebSQL
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如果在浏览器环境中使用TypeORM需要使用 `npm i typeorm-browser` 来替代 `typeorm`.
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更多相关可以参考[这里](https://typeorm.github.io/usage-in-browser.html)和[这个例子](https://github.com/typeorm/browser-example).
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## 快速开始
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在TypeORM中，数据库table都是从实体中创建。
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所谓*实体*其实就是用装饰器`@Table`装饰的一个model。
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可以直接从数据库中得到包含数据的实体对象，并且可以通过实体进行数据库表的insert/update/remove。
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来看看这个model `entity/Photo.ts`:
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```typescript
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export class Photo {
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id: number;
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name: string;
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description: string;
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fileName: string;
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views: number;
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}
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```
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### 创建实体
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现在把Model变成实体:
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```typescript
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import {Table} from "typeorm";
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@Table()
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export class Photo {
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id: number;
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name: string;
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description: string;
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fileName: string;
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views: number;
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isPublished: boolean;
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}
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```
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### 添加table列
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已经有了一个table，每个table都有column.
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现在来添加列.
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可以使用装饰器`@Column`来把model的属性变成列：
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```typescript
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import {Table, Column} from "typeorm";
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@Table()
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export class Photo {
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@Column()
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id: number;
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@Column()
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name: string;
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@Column()
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description: string;
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@Column()
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fileName: string;
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@Column()
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views: number;
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@Column()
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isPublished: boolean;
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}
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```
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### 创建一个主键列
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很好， 现在ORM马上就可以在数据库中生成这个photo表，不过还漏了一个，每个table都必须要有主键列，所以要加上它。
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可以用`@PrimaryColumn`装饰器来标记一个主键列。
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```typescript
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import {Table, Column, PrimaryColumn} from "typeorm";
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@Table()
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export class Photo {
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@PrimaryColumn()
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id: number;
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@Column()
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name: string;
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@Column()
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description: string;
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@Column()
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fileName: string;
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@Column()
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views: number;
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@Column()
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isPublished: boolean;
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}
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```
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### 创建自增长/自生成/顺序化的列
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如果你想创建自增长/自生成/顺序化的列，需要把column的type改成integer并且给主键列加上一个属性`{ generated: true }`
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```typescript
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import {Table, Column, PrimaryColumn} from "typeorm";
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@Table()
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export class Photo {
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@PrimaryColumn("int", { generated: true })
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id: number;
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@Column()
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name: string;
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@Column()
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description: string;
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@Column()
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fileName: string;
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@Column()
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views: number;
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@Column()
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isPublished: boolean;
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}
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```
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### 使用 `@PrimaryGeneratedColumn` 装饰器
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现在photo表的id可能自动生成自动增长，不过还是有点麻烦，这个一个很常见的功能，所以有一个专门的装饰器`@PrimaryGeneratedColumn`来实现相同的功能。
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```typescript
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import {Table, Column, PrimaryGeneratedColumn} from "typeorm";
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@Table()
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export class Photo {
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@PrimaryGeneratedColumn()
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id: number;
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@Column()
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name: string;
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@Column()
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description: string;
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@Column()
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fileName: string;
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@Column()
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views: number;
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@Column()
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isPublished: boolean;
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}
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```
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### 自定义列的数据类型
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接下来让我们改一下列的数据类型。默认情况下，string类型的属性会映射到数据库里varchar(255)的数据类型，number则会映射到类似于float/double这样的数据类型（取决到是什么数据库）。
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但是我们不想所有的列被限制在varchar或float之类，下面来改进：
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```typescript
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import {Table, Column, PrimaryGeneratedColumn} from "typeorm";
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@Table()
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export class Photo {
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@PrimaryGeneratedColumn()
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id: number;
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@Column({
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length: 500
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})
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name: string;
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@Column("text")
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description: string;
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@Column()
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fileName: string;
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@Column("int")
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views: number;
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@Column()
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isPublished: boolean;
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}
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```
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### 创建数据库连接
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现在实体已经有了，接下来创建`app.ts`并配置数据库连接：
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```typescript
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import "reflect-metadata";
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import {createConnection} from "typeorm";
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import {Photo} from "./entity/Photo";
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createConnection({
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driver: {
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type: "mysql",
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host: "localhost",
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port: 3306,
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username: "root",
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password: "admin",
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database: "test"
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},
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entities: [
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Photo
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],
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autoSchemaSync: true,
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}).then(connection => {
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// 这里可以写实体操作相关的代码
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}).catch(error => console.log(error));
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```
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在例子里使用的是mysql，你也可以选择其他数据库，只需要简单修改driver选项里的数据库的类型就可以了，比如：
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mysql, mariadb, postgres, sqlite, mssql or oracle.
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同样可以修改host, port, username, password 以及database等设置.
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把Photo实体加到数据连接的实体列表中，所有需要在这个连接下使用的实体都必须加到这个列表中。
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`autoSchemaSync`选项可以在应用启动时确保你的实体和数据库保持同步。
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### 引用目录下的所有实体
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接下来我们可能会创建更多的实体并把它们一一加到配置当中。
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不过这样会比较麻烦，好在可以直接写上实体的目录，这样这个目录下的所有实体都可以在当前连接中被使用：
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```typescript
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import {createConnection} from "typeorm";
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createConnection({
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driver: {
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type: "mysql",
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host: "localhost",
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port: 3306,
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username: "root",
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password: "admin",
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database: "test"
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},
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entities: [
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__dirname + "/entity/*.js"
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],
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autoSchemaSync: true,
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}).then(connection => {
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// here you can start to work with your entities
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}).catch(error => console.log(error));
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```
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### 启动应用
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现在可以启动`app.ts`，启动后可以发现数据库自动被初始化，并且Photo这个表也会创建出来。
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```shell
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+-------------+--------------+----------------------------+
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| photo |
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+-------------+--------------+----------------------------+
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| id | int(11) | PRIMARY KEY AUTO_INCREMENT |
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| name | varchar(500) | |
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| description | text | |
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| filename | varchar(255) | |
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| views | int(11) | |
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| isPublished | boolean | |
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+-------------+--------------+----------------------------+
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```
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### 添加和插入photo
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现在创建一个新的photo然后存到数据库：
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```typescript
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import {createConnection} from "typeorm";
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createConnection(/*...*/).then(connection => {
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let photo = new Photo();
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photo.name = "Me and Bears";
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photo.description = "I am near polar bears";
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photo.filename = "photo-with-bears.jpg";
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photo.views = 1;
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photo.isPublished = true;
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connection.entityManager
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.persist(photo)
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.then(photo => {
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console.log("Photo has been saved");
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});
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}).catch(error => console.log(error));
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```
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### 使用async/await语法
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现在利用TypeScript的async/await语法来实现同样的功能：
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```typescript
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import {createConnection} from "typeorm";
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import {Photo} from "./entity/Photo";
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createConnection(/*...*/).then(async connection => {
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let photo = new Photo();
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photo.name = "Me and Bears";
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photo.description = "I am near polar bears";
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photo.filename = "photo-with-bears.jpg";
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photo.views = 1;
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photo.isPublished = true;
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await connection.entityManager.persist(photo);
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console.log("Photo has been saved");
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}).catch(error => console.log(error));
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```
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### 使用EntityManager
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刚刚我们创建了一个新的photo并且存进数据库。使用EntityManager可以操作实体，现在用`EntityManager`来把photo从数据库中取出来。
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```typescript
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import {createConnection} from "typeorm";
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import {Photo} from "./entity/Photo";
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createConnection(/*...*/).then(async connection => {
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/*...*/
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let savedPhotos = await connection.entityManager.find(Photo);
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console.log("All photos from the db: ", savedPhotos);
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}).catch(error => console.log(error));
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```
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savedPhotos 会从数据库中取到的是一个Photo对象的数组
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### 使用Repositories
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现在重构下代码，使用`Repository`来代替EntityManage。每个实体都有自己的repository，可以对这个实体进行任何操作。
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如果要对实体做很多操作，Repositories会比EntityManager更加方便。
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```typescript
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import {createConnection} from "typeorm";
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import {Photo} from "./entity/Photo";
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createConnection(/*...*/).then(async connection => {
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let photo = new Photo();
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photo.name = "Me and Bears";
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photo.description = "I am near polar bears";
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photo.filename = "photo-with-bears.jpg";
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photo.views = 1;
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photo.isPublished = true;
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let photoRepository = connection.getRepository(Photo);
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await photoRepository.persist(photo);
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console.log("Photo has been saved");
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let savedPhotos = await photoRepository.find();
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console.log("All photos from the db: ", savedPhotos);
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}).catch(error => console.log(error));
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```
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### 从数据库中取photos
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现在来尝试用Repository做一些取数据方面的操作:
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|
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```typescript
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import {createConnection} from "typeorm";
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import {Photo} from "./entity/Photo";
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createConnection(/*...*/).then(async connection => {
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/*...*/
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let allPhotos = await photoRepository.find();
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console.log("All photos from the db: ", allPhotos);
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let firstPhoto = await photoRepository.findOneById(1);
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console.log("First photo from the db: ", firstPhoto);
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let meAndBearsPhoto = await photoRepository.findOne({ name: "Me and Bears" });
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console.log("Me and Bears photo from the db: ", meAndBearsPhoto);
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let allViewedPhotos = await photoRepository.find({ views: 1 });
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console.log("All viewed photos: ", allViewedPhotos);
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let allPublishedPhotos = await photoRepository.find({ isPublished: true });
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console.log("All published photos: ", allPublishedPhotos);
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let [allPhotos, photosCount] = await photoRepository.findAndCount();
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console.log("All photos: ", allPublishedPhotos);
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console.log("Photos count: ", allPublishedPhotos);
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}).catch(error => console.log(error));
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```
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### 更新photo
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||||
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现在来从数据库中取出一个photo，修改并更新到数据库。
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```typescript
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import {createConnection} from "typeorm";
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import {Photo} from "./entity/Photo";
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createConnection(/*...*/).then(async connection => {
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/*...*/
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let photoToUpdate = await photoRepository.findOneById(1);
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photoToUpdate.name = "Me, my friends and polar bears";
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await photoRepository.persist(photoToUpdate);
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}).catch(error => console.log(error));
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```
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这个`id = 1`的photo在数据库中就成功更新了.
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### 删除photo
|
||||
|
||||
再来，从数据库中删除我们的photo:
|
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|
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|
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```typescript
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import {createConnection} from "typeorm";
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import {Photo} from "./entity/Photo";
|
||||
|
||||
createConnection(/*...*/).then(async connection => {
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|
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/*...*/
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let photoToRemove = await photoRepository.findOneById(1);
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await photoRepository.remove(photoToRemove);
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|
||||
}).catch(error => console.log(error));
|
||||
```
|
||||
|
||||
这个`id = 1`的photo就在数据库中被移除了。
|
||||
|
||||
### 一对一关系
|
||||
|
||||
来创建与另一个类的一对一关系。
|
||||
新建PhotoMetadata.ts用来存photo的元信息。
|
||||
|
||||
```typescript
|
||||
import {Table, Column, PrimaryGeneratedColumn, OneToOne, JoinColumn} from "typeorm";
|
||||
import {Photo} from "./Photo";
|
||||
|
||||
@Table()
|
||||
export class PhotoMetadata {
|
||||
|
||||
@PrimaryGeneratedColumn()
|
||||
id: number;
|
||||
|
||||
@Column("int")
|
||||
height: number;
|
||||
|
||||
@Column("int")
|
||||
width: number;
|
||||
|
||||
@Column()
|
||||
orientation: string;
|
||||
|
||||
@Column()
|
||||
compressed: boolean;
|
||||
|
||||
@Column()
|
||||
comment: string;
|
||||
|
||||
@OneToOne(type => Photo)
|
||||
@JoinColumn()
|
||||
photo: Photo;
|
||||
}
|
||||
```
|
||||
|
||||
这里我们用到了一个新的装饰器`@OneToOne`，它可以用来在两个实体之间创建一对一关系。
|
||||
`type => Photo`指示了我们想要连接的实体类名，这里因为TypeScript语言的支持原因不能直接用类名。
|
||||
当然也可以使用`() => Photo`，但是`type => Photo`显得更有可读性。
|
||||
Type变量本身并不包含任何东西。
|
||||
|
||||
我们同样使用了`@JoinColumn`装饰器，这个装饰器可以指定一对一关系的拥有者。
|
||||
关系可以是单向的或双向的，但是只有一方是拥有者，加个这个装饰器就表示关系是给这个表服务的。
|
||||
|
||||
现在运行app，会新创建一个table，这个table有一个连接photo的外键：
|
||||
|
||||
```shell
|
||||
+-------------+--------------+----------------------------+
|
||||
| photo `译者注：应该是PhotoMetadata` |
|
||||
+-------------+--------------+----------------------------+
|
||||
| id | int(11) | PRIMARY KEY AUTO_INCREMENT |
|
||||
| height | int(11) | |
|
||||
| width | int(11) | |
|
||||
| comment | varchar(255) | |
|
||||
| compressed | boolean | |
|
||||
| orientation | varchar(255) | |
|
||||
| photo | int(11) | FOREIGN KEY |
|
||||
+-------------+--------------+----------------------------+
|
||||
```
|
||||
|
||||
### 存一个有一对一关系的对象
|
||||
|
||||
现在来创建一个photo，一个photo的元信息，并把它们已经连接起来。
|
||||
|
||||
```typescript
|
||||
import {createConnection} from "typeorm";
|
||||
import {Photo} from "./entity/Photo";
|
||||
import {PhotoMetadata} from "./entity/PhotoMetadata";
|
||||
|
||||
createConnection(/*...*/).then(async connection => {
|
||||
|
||||
// 创建一个photo
|
||||
let photo = new Photo();
|
||||
photo.name = "Me and Bears";
|
||||
photo.description = "I am near polar bears";
|
||||
photo.filename = "photo-with-bears.jpg"
|
||||
photo.isPublished = true;
|
||||
|
||||
// 创建一个photo的元信息
|
||||
let metadata = new PhotoMetadata();
|
||||
metadata.height = 640;
|
||||
metadata.width = 480;
|
||||
metadata.compressed = true;
|
||||
metadata.comment = "cybershoot";
|
||||
metadata.orientation = "portait";
|
||||
metadata.photo = photo; // 这里把两者连起来
|
||||
|
||||
// 获取实体repositories
|
||||
let photoRepository = connection.getRepository(Photo);
|
||||
let metadataRepository = connection.getRepository(PhotoMetadata);
|
||||
|
||||
// 先来把photo存到数据库
|
||||
await photoRepository.persist(photo);
|
||||
|
||||
// photo存完了，再存下photo的元信息
|
||||
await metadataRepository.persist(metadata);
|
||||
|
||||
// 搞定
|
||||
console.log("metadata is saved, and relation between metadata and photo is created in the database too");
|
||||
|
||||
}).catch(error => console.log(error));
|
||||
```
|
||||
|
||||
### 双向关系
|
||||
|
||||
关系可以是单向的或是双向的.
|
||||
现在PhotoMetadata和Photo的关系是单向的，关系拥有者是PhotoMetadata，Photo并不知道PhotoMetadata，这样如果要想从Photo里得到PhotoMetadata的数据会比较麻烦。
|
||||
现在来改变一下，把单向改成双向：
|
||||
|
||||
```typescript
|
||||
import {Table, Column, PrimaryGeneratedColumn, OneToOne, JoinColumn} from "typeorm";
|
||||
import {Photo} from "./Photo";
|
||||
|
||||
@Table()
|
||||
export class PhotoMetadata {
|
||||
|
||||
/* ... 其他列 */
|
||||
|
||||
@OneToOne(type => Photo, photo => photo.metadata)
|
||||
@JoinColumn()
|
||||
photo: Photo;
|
||||
}
|
||||
```
|
||||
|
||||
```typescript
|
||||
import {Table, Column, PrimaryGeneratedColumn, OneToOne} from "typeorm";
|
||||
import {PhotoMetadata} from "./PhotoMetadata";
|
||||
|
||||
@Table()
|
||||
export class Photo {
|
||||
|
||||
/* ... 其他列 */
|
||||
|
||||
@OneToOne(type => PhotoMetadata, photoMetadata => photoMetadata.photo)
|
||||
metadata: PhotoMetadata;
|
||||
}
|
||||
```
|
||||
|
||||
`photo => photo.metadata` 是用来指定反向关系的字段名字，photo.metadata就指出了Photo里的metadata字段名字。
|
||||
当然也可以使用`@OneToOne('metadata')`来达到同样的目的，不过这种对于以后的代码重构不友好。
|
||||
|
||||
按上面说的，`@JoinColumn`只能在关系的一边使用来使这边做为关系的拥有者，关系拥有者在数据库里的表现就是拥有一个外键列。
|
||||
|
||||
### 取出关系对象的数据
|
||||
|
||||
现在来用一个查询来取出photo以及它的元信息。
|
||||
有两种方式，一是用`FindOptions`，另一个是使用`QueryBuilder`。
|
||||
先试下`FindOptions`，通过指定`FindOptions`接口作为参数来使用`Repository.find`方法可以完成非常复杂的查询。
|
||||
|
||||
```typescript
|
||||
import {createConnection} from "typeorm";
|
||||
import {Photo} from "./entity/Photo";
|
||||
import {PhotoMetadata} from "./entity/PhotoMetadata";
|
||||
|
||||
createConnection(/*...*/).then(async connection => {
|
||||
|
||||
/*...*/
|
||||
let photoRepository = connection.getRepository(Photo);
|
||||
let photos = await photoRepository.find({
|
||||
alias: "photo",
|
||||
innerJoinAndSelect: {
|
||||
"metadata": "photo.metadata"
|
||||
}
|
||||
});
|
||||
|
||||
|
||||
}).catch(error => console.log(error));
|
||||
```
|
||||
返回的photos是从数据库里取回的photo的数组，每个photo都包含它的元信息。
|
||||
|
||||
`alias` 是FindOptions的一个必需选项，这是你自己在select里定义的别名，然后需要用在接下来的 where, order by, group by, join 以及其他表达式.
|
||||
|
||||
这里还用到了`innerJoinAndSelect`，表示内联查询photo.metadata的数据。
|
||||
`"photo.metadata"`里"photo"是一个别名，"metadata"则是你想查询的那个对象的属性名。
|
||||
`"metadata"`: 是内联返回数据的新的别名.
|
||||
|
||||
下面来尝试第二种方式：`QueryBuilder`来达到同样的目的. 使用`QueryBuilder`可以优雅完成复杂的查询:
|
||||
|
||||
```typescript
|
||||
import {createConnection} from "typeorm";
|
||||
import {Photo} from "./entity/Photo";
|
||||
import {PhotoMetadata} from "./entity/PhotoMetadata";
|
||||
|
||||
createConnection(/*...*/).then(async connection => {
|
||||
|
||||
/*...*/
|
||||
let photoRepository = connection.getRepository(Photo);
|
||||
let photos = await photoRepository.createQueryBuilder("photo")
|
||||
.innerJoinAndSelect("photo.metadata", "metadata")
|
||||
.getMany();
|
||||
|
||||
|
||||
}).catch(error => console.log(error));
|
||||
```
|
||||
|
||||
### 使用 cascade 选项来自动保存关系着的对象
|
||||
|
||||
上面要保存关系对象需要一个一个来保存，略显麻烦。
|
||||
如果我们需要当关系对象中的一个被保存后，另一个也同样被保存，则可以使用`cascade`选项来做到。
|
||||
稍微改下`@OneToOne`装饰:
|
||||
|
||||
```typescript
|
||||
export class Photo {
|
||||
/// ... 其他列
|
||||
|
||||
@OneToOne(type => PhotoMetadata, metadata => metadata.photo, {
|
||||
cascadeInsert: true,
|
||||
cascadeUpdate: true,
|
||||
cascadeRemove: true
|
||||
})
|
||||
metadata: PhotoMetadata;
|
||||
}
|
||||
```
|
||||
|
||||
* **cascadeInsert** - 如果表中没有关系中的metadata，则自动insert，即我们不需要再手动insert一个新的photoMetadata对象。
|
||||
* **cascadeUpdate** - 如果metadata有变化，则自动update。
|
||||
* **cascadeRemove** - 如果把photo里的metadata移除了，也就是为空，则会自动remove表中的这条metadata数据。
|
||||
|
||||
使用cascadeInsert就可以不需要像上面那边先存photo再存metadata了。
|
||||
现在我们来单单存photo对象，由于cascade的作用，metadata也会自动存上。
|
||||
|
||||
```typescript
|
||||
createConnection(options).then(async connection => {
|
||||
|
||||
// 创建photo对象
|
||||
let photo = new Photo();
|
||||
photo.name = "Me and Bears";
|
||||
photo.description = "I am near polar bears";
|
||||
photo.filename = "photo-with-bears.jpg"
|
||||
photo.isPublished = true;
|
||||
|
||||
// 创建photo metadata 对象
|
||||
let metadata = new PhotoMetadata();
|
||||
metadata.height = 640;
|
||||
metadata.width = 480;
|
||||
metadata.compressed = true;
|
||||
metadata.comment = "cybershoot";
|
||||
metadata.orientation = "portait";
|
||||
|
||||
photo.metadata = metadata; // 连接起来
|
||||
|
||||
// 得到repository
|
||||
let photoRepository = connection.getRepository(Photo);
|
||||
|
||||
// 存photo
|
||||
await photoRepository.persist(photo);
|
||||
// photo metadata也自动存上了
|
||||
console.log("Photo is saved, photo metadata is saved too.")
|
||||
|
||||
}).catch(error => console.log(error));
|
||||
```
|
||||
|
||||
### 多对一/一对多关系
|
||||
|
||||
接下来显示多对一/一对多关系。
|
||||
假设一个photo会有一个author，并且每个author可以有很多photo。
|
||||
先创建Author实体：
|
||||
|
||||
```typescript
|
||||
import {Table, Column, PrimaryGeneratedColumn, OneToMany, JoinColumn} from "typeorm";
|
||||
import {Photo} from "./Photo";
|
||||
|
||||
@Table()
|
||||
export class Author {
|
||||
|
||||
@PrimaryGeneratedColumn()
|
||||
id: number;
|
||||
|
||||
@Column()
|
||||
name: string;
|
||||
|
||||
@OneToMany(type => Photo, photo => photo.author) // 备注：下面会为Photo创建author属性
|
||||
photos: Photo[];
|
||||
}
|
||||
```
|
||||
|
||||
Author包含一个反向的关系，`OneToMany`总是反向的，并且总是与`ManyToOne`成对出现。
|
||||
|
||||
现在来为Photo加上关系拥有者。
|
||||
|
||||
```typescript
|
||||
import {Table, Column, PrimaryGeneratedColumn, ManyToOne} from "typeorm";
|
||||
import {PhotoMetadata} from "./PhotoMetadata";
|
||||
import {Author} from "./Author";
|
||||
|
||||
@Table()
|
||||
export class Photo {
|
||||
|
||||
/* ... 其他列 */
|
||||
|
||||
@ManyToOne(type => Author, author => author.photos)
|
||||
author: Author;
|
||||
}
|
||||
```
|
||||
|
||||
在`ManyToOne/OneToMany`关系中，拥有者一边总是`ManyToOne`。`译者注：拥有外键者即关系拥有者`
|
||||
也就是`ManyToOne`的那个字段存的是另一个对象的id。`译者注：也就是上面的author虽然属性是Author，但在数据库中类型是Author id的类型，存的也是id`
|
||||
|
||||
执行上面的代码将会自动创建author表，如下:
|
||||
|
||||
|
||||
```shell
|
||||
+-------------+--------------+----------------------------+
|
||||
| author |
|
||||
+-------------+--------------+----------------------------+
|
||||
| id | int(11) | PRIMARY KEY AUTO_INCREMENT |
|
||||
| name | varchar(255) | |
|
||||
+-------------+--------------+----------------------------+
|
||||
```
|
||||
|
||||
因为photo表已经存在，所以不是增加而是修改photo表 - 添加一个新外键列author:
|
||||
|
||||
```shell
|
||||
+-------------+--------------+----------------------------+
|
||||
| photo |
|
||||
+-------------+--------------+----------------------------+
|
||||
| id | int(11) | PRIMARY KEY AUTO_INCREMENT |
|
||||
| name | varchar(255) | |
|
||||
| description | varchar(255) | |
|
||||
| filename | varchar(255) | |
|
||||
| isPublished | boolean | |
|
||||
| author | int(11) | FOREIGN KEY |
|
||||
+-------------+--------------+----------------------------+
|
||||
```
|
||||
|
||||
### 多对多关系
|
||||
|
||||
假设photo可以存在多个相册中，并且相册里可以包含多个photo。
|
||||
先创建一个`Album`类
|
||||
|
||||
```typescript
|
||||
import {Table, PrimaryGeneratedColumn, Column, ManyToMany, JoinTable} from "typeorm";
|
||||
|
||||
@Table()
|
||||
export class Album {
|
||||
|
||||
@PrimaryGeneratedColumn()
|
||||
id: number;
|
||||
|
||||
@Column()
|
||||
name: string;
|
||||
|
||||
@ManyToMany(type => Photo, photo => photo.albums, { // 备注: 会在下面的Photo类里添加"albums"属性
|
||||
cascadeInsert: true, // 在添加Album时，会自动添加相册里的Photo
|
||||
cascadeUpdate: true, // 在更新Album时，会自动更新相册里的Photo
|
||||
cascadeRemove: true // 在移除Album时，会自动移除相册里的Photo
|
||||
})
|
||||
@JoinTable()
|
||||
photos: Photo[] = []; // 初始化个Photo数组
|
||||
}
|
||||
```
|
||||
|
||||
`@JoinTable`多对多关系拥有者必须指定的。
|
||||
|
||||
接着给`Photo`实体加个反向关系:
|
||||
|
||||
```typescript
|
||||
export class Photo {
|
||||
/// ... 其他列
|
||||
|
||||
@ManyToMany(type => Album, album => album.photos, {
|
||||
cascadeInsert: true, // 在添加Album时，会自动添加相册里的Photo
|
||||
cascadeUpdate: true, // 在更新Album时，会自动更新相册里的Photo
|
||||
cascadeRemove: true // 在移除Album时，会自动移除相册里的Photo
|
||||
})
|
||||
albums: Album[] = []; // 初始化个Album数组
|
||||
}
|
||||
```
|
||||
|
||||
执行上面的代码后会自动创建一个叫 **album_photos_photo_albums**的*联接表*:
|
||||
|
||||
```shell
|
||||
+-------------+--------------+----------------------------+
|
||||
| album_photos_photo_albums |
|
||||
+-------------+--------------+----------------------------+
|
||||
| album_id_1 | int(11) | PRIMARY KEY FOREIGN KEY |
|
||||
| photo_id_2 | int(11) | PRIMARY KEY FOREIGN KEY |
|
||||
+-------------+--------------+----------------------------+
|
||||
```
|
||||
|
||||
记得把`Album`实体加到ConnectionOptions中:
|
||||
|
||||
```typescript
|
||||
const options: CreateConnectionOptions = {
|
||||
// ... 其他配置
|
||||
entities: [Photo, PhotoMetadata, Author, Album]
|
||||
};
|
||||
```
|
||||
|
||||
现在来往数据库里插入albums和photos
|
||||
|
||||
```typescript
|
||||
let connection = await createConnection(options);
|
||||
|
||||
// 创建两个albums
|
||||
let album1 = new Album();
|
||||
album1.name = "Bears";
|
||||
|
||||
let album2 = new Album();
|
||||
album2.name = "Me";
|
||||
|
||||
// 创建两个photos
|
||||
let photo1 = new Photo();
|
||||
photo1.name = "Me and Bears";
|
||||
photo1.description = "I am near polar bears";
|
||||
photo1.filename = "photo-with-bears.jpg";
|
||||
photo1.albums.push(album1);
|
||||
|
||||
let photo2 = new Photo();
|
||||
photo2.name = "Me and Bears";
|
||||
photo2.description = "I am near polar bears";
|
||||
photo2.filename = "photo-with-bears.jpg";
|
||||
photo2.albums.push(album2);
|
||||
|
||||
// 获取Photo的repository
|
||||
let photoRepository = connection.getRepository(Photo);
|
||||
|
||||
// 依次存储photos，由于cascade，albums也同样会自动存起来
|
||||
await photoRepository.persist(photo1);
|
||||
await photoRepository.persist(photo2);
|
||||
|
||||
console.log("Both photos have been saved");
|
||||
```
|
||||
|
||||
### 使用QueryBuilder
|
||||
|
||||
可以利用QueryBuilder来构建一个非常复杂的查询，例如：
|
||||
|
||||
```typescript
|
||||
let photoRepository = connection.getRepository(Photo);
|
||||
let photos = await photoRepository
|
||||
.createQueryBuilder("photo") // 别名，必填项，用来指定本次查询
|
||||
.innerJoinAndSelect("photo.metadata", "metadata")
|
||||
.leftJoinAndSelect("photo.albums", "albums")
|
||||
.where("photo.isPublished=true")
|
||||
.andWhere("(photo.name=:photoName OR photo.name=:bearName)")
|
||||
.orderBy("photo.id", "DESC")
|
||||
.setFirstResult(5)
|
||||
.setMaxResults(10)
|
||||
.setParameters({ photoName: "My", bearName: "Mishka" })
|
||||
.getMany();
|
||||
```
|
||||
|
||||
这个查询会查找已经published的，并且name是"My"或"Mishka"，
|
||||
得到的结果会从第5个开始（分页偏移决定的），
|
||||
并且只会得到10个结果（分页每页个数决定的），
|
||||
所得结果是以id的倒序排序的，
|
||||
Photo的albums是左联接，photo的metadata是内联接。
|
||||
|
||||
更多关于QueryBuilder可以查看[这里](https://typeorm.github.io/query-builder.html).
|
||||
Loading…
x
Reference in New Issue
Block a user