typeorm装饰器之Entity

原创于 2018-01-06 20:13:16 发布 · 1.4k 阅读

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本文介绍了一个实体装饰器的实现方式，展示了如何通过不同的参数配置来创建数据库表，并提供了多个示例说明实体装饰器的使用方法。

src/decorator/entity/Entity.ts

import {getMetadataArgsStorage} from "../../index";
import {TableMetadataArgs} from "../../metadata-args/TableMetadataArgs";
import {EntityOptions} from "../options/EntityOptions";

//实体装饰器工厂方法声明
export function Entity(options?: EntityOptions): Function;

//第一个参数为实体表名
export function Entity(name?: string, options?: EntityOptions): Function;

//工厂方法方法实现
export function Entity(nameOrOptions?: string|EntityOptions, maybeOptions?: EntityOptions): Function {
    //获取选项
    const options = (typeof nameOrOptions === "object" ? nameOrOptions as EntityOptions : maybeOptions) || {};
    //表名
    const name = typeof nameOrOptions === "string" ? nameOrOptions : options.name;
    //返回装饰器
    return function (target: Function) {
        //表元数据参数
        const args: TableMetadataArgs = {
            //实体类构造函数
            target: target,
            //表名
            name: name,
            //类型
            type: "regular",
            //查询结果默认排序
            orderBy: options && options.orderBy ? options.orderBy : undefined,
            //引擎
            engine: options && options.engine ? options.engine : undefined,
            //所属数据库，可以覆盖连接选项中的数据库
            database: options && options.database ? options.database : undefined,
            //schema，个别数据库支持
            schema: options && options.schema ? options.schema : undefined,
            //是否跳过同步，即连接如果设置为 synchronize: true时，是否跳过同步这个表
            skipSync: !!(options && options.skipSync === true)
        };
        //添加元数据参数
        getMetadataArgsStorage().tables.push(args);
    };
}

测试1：

import {Column, Entity} from "../../../src/index";
import {PrimaryColumn} from "../../../src/decorator/columns/PrimaryColumn";
import {Generated} from "../../../src/decorator/Generated";

@Entity()
export class Post {

    @PrimaryColumn("integer")
    id: number;
}

表结构：

+-------+------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                               |
+-------+------------------------------------------------------------------------------------------------------------+
| post  | CREATE TABLE `post` (
  `id` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+------------------------------------------------------------------------------------------------------------+

默认情况下，表名为实体名小写

测试2：

import {Column, Entity} from "../../../src/index";
import {PrimaryColumn} from "../../../src/decorator/columns/PrimaryColumn";
import {Generated} from "../../../src/decorator/Generated";

@Entity('post_test')
export class Post {

    @PrimaryColumn("integer")
    id: number;
}

表结构：

+-----------+-----------------------------------------------------------------------------------------------------------------+
| Table     | Create Table                                                                                                    |
+-----------+-----------------------------------------------------------------------------------------------------------------+
| post_test | CREATE TABLE `post_test` (
  `id` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-----------+-----------------------------------------------------------------------------------------------------------------+

第一个参数为字符串，则为表名

测试3：

import {Column, Entity} from "../../../src/index";
import {PrimaryColumn} from "../../../src/decorator/columns/PrimaryColumn";
import {Generated} from "../../../src/decorator/Generated";

@Entity({
    name:'post_test1',
    engine:'myisam'

})
export class Post {
    @PrimaryColumn("integer")
    id: number;
}

表结构：

+------------+------------------------------------------------------------------------------------------------------------------+
| Table      | Create Table                                                                                                     |
+------------+------------------------------------------------------------------------------------------------------------------+
| post_test1 | CREATE TABLE `post_test1` (
  `id` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 |
+------------+------------------------------------------------------------------------------------------------------------------+

当第一个参数为对象时，则为选项，name属性为表名，设置了引擎为MyISAM，只有mysql支持引擎

测试4：

import {Column, Entity} from "../../../src/index";
import {PrimaryColumn} from "../../../src/decorator/columns/PrimaryColumn";
import {Generated} from "../../../src/decorator/Generated";

@Entity({
    name:'post_test1',
    engine:'myisam',
    skipSync:true

})
export class Post {
    @PrimaryColumn("integer")
    id: number;
}

这个实体跳过了连接的同步步骤，没有生成表