【一周一荐】| typeorm一款极好的nodejs orm框架

最近希望使用Nodejs给我提供后端服务，但是数据库操作这块实在是麻烦，所以想着找一个现成的ORM框架来进行数据库映射、连接、操作功能。由于我的软件准备采用midway + TS框架，所以我这边使用TypeORM作为ORM框架。这里记录总结一些TypeORM常用的操作。

安装

我这里使用mysql作为数据库，ts作为主要开发语言，所以本文所有使用基于mysql数据库驱动之上。

$ npm install mysql typeorm reflect-metadata --save
$ npm install @types/node --save // ts类型声明

tsconfig.json配置

需要保证TypeScript的编译器版本在2.3之上，并在tsconfig.json中启用如下两个模块：

// tsconfig.json
{
  "compileOnSave": true,
  "compilerOptions": {
    "target": "es2018",
    "module": "commonjs",
    "moduleResolution": "node",
    "experimentalDecorators": true,  //  typeorm需要启用
    "emitDecoratorMetadata": true,  // typeorm需要启用
    "inlineSourceMap":true,
    "noImplicitThis": true,
    "noUnusedLocals": true,
    "stripInternal": true,
    "skipLibCheck": true,
    "pretty": true,
    "declaration": true,
    "noImplicitAny": false,
    "typeRoots": [ "./typings", "./node_modules/@types"],
    "outDir": "dist"
  },
  "exclude": [
    "dist",
    "node_modules",
    "test"
  ]
}

配置

新建ormconfig.json文件，并添加数据库连接配置：

{
  "type": "mysql",
  "host": "localhost", 
  "port": 3306,
  "username": "root",
  "password": "root",
  "database": "test",
  "synchronize": true,
  "logging": false,
  "entities": ["src/entity/**/*.ts"], // 实体类位置
  "migrations": ["src/migration/**/*.ts"], // 迁移
  "subscribers": ["src/subscriber/**/*.ts"] // 订阅
}

我们也可以在代码中通过配置连接：

import { createConnection, Connection } from "typeorm";

const connection = await createConnection({
  type: "mysql",
  host: "localhost",
  port: 3306,
  username: "test",
  password: "test",
  database: "test"，
  entities: ["src/entity/**/*.ts"],
  migrations: ["src/migration/**/*.ts"],

  subscribers: ["src/subscriber/**/*.ts"]
});

同时，TypeORM也支持主从复制配置和读写分离配置，参考：Nodejs使用typeorm实现mysql的读写分离

实体创建

TypeORM中配置指定位置的实体类其实际回主动映射到对应的数据表中，我们创建一个实体类其实就是创建一个数据表。代码如下：

import { Entity, PrimaryGeneratedColumn, Column } from "typeorm";

// 通过entity注入创建数据表，可通过传入表名创建自定义表，若未传入则创建一个和类名相同的表
@Entity("sys_base_user")
export class User {

    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    firstName: string;

    @Column()
    lastName: string;

    @Column()
    isActive: boolean;
}

创建的表结构如下：

+-------------+--------------+----------------------------+
|                          sys_base_user|
+-------------+--------------+----------------------------+
| id          | int(11)      | PRIMARY KEY AUTO_INCREMENT |
| firstName   | varchar(255) |                            |
| lastName    | varchar(255) |                            |
| isActive    | boolean      |                            |
+-------------+--------------+----------------------------+

基本实体由列和关系组成。 每个实体必须有一个主键（primary key），每个实体都需要在连接时被注册，但由于我们上面已经配置注册完成了，这里可以不用管。如上可知，我们可以通过 @Column()来定义我们的列数据，typeorm会根据列数据定义的类型自动在对应表中创建一个相同的列，其常见格式如下：

@Column("varchar", { length: 200 }) // 或者
@Column({ type: "int",comment })

Column支持配置参数如下：

• type?: ColumnType：列数据类型，其支持参数如下

export type PrimaryGeneratedColumnType = "int" | "int2" | "int4" | "int8" | "integer" | "tinyint" | "smallint" | "mediumint" | "bigint" | "dec" | "decimal" | "smalldecimal" | "fixed" | "numeric" | "number";
/**
 * Column types where spatial properties are used.
 */
export type SpatialColumnType = "geometry" | "geography" | "st_geometry" | "st_point";
/**
 * Column types where precision and scale properties are used.
 */
export type WithPrecisionColumnType = "float" | "double" | "dec" | "decimal" | "smalldecimal" | "fixed" | "numeric" | "real" | "double precision" | "number" | "datetime" | "datetime2" | "datetimeoffset" | "time" | "time with time zone" | "time without time zone" | "timestamp" | "timestamp without time zone" | "timestamp with time zone" | "timestamp with local time zone";
/**
 * Column types where column length is used.
 */
export type WithLengthColumnType = "character varying" | "varying character" | "char varying" | "nvarchar" | "national varchar" | "character" | "native character" | "varchar" | "char" | "nchar" | "national char" | "varchar2" | "nvarchar2" | "alphanum" | "shorttext" | "raw" | "binary" | "varbinary" | "string";
export type WithWidthColumnType = "tinyint" | "smallint" | "mediumint" | "int" | "bigint";
/**
 * All other regular column types.
 */
export type SimpleColumnType = "simple-array" | "simple-json" | "simple-enum" | "int2" | "integer" | "int4" | "int8" | "int64" | "unsigned big int" | "float" | "float4" | "float8" | "float64" | "smallmoney" | "money" | "boolean" | "bool" | "tinyblob" | "tinytext" | "mediumblob" | "mediumtext" | "blob" | "text" | "ntext" | "citext" | "hstore" | "longblob" | "longtext" | "alphanum" | "shorttext" | "bytes" | "bytea" | "long" | "raw" | "long raw" | "bfile" | "clob" | "nclob" | "image" | "timetz" | "timestamptz" | "timestamp with local time zone" | "smalldatetime" | "date" | "interval year to month" | "interval day to second" | "interval" | "year" | "seconddate" | "point" | "line" | "lseg" | "box" | "circle" | "path" | "polygon" | "geography" | "geometry" | "linestring" | "multipoint" | "multilinestring" | "multipolygon" | "geometrycollection" | "st_geometry" | "st_point" | "int4range" | "int8range" | "numrange" | "tsrange" | "tstzrange" | "daterange" | "enum" | "set" | "cidr" | "inet" | "inet4" | "inet6" | "macaddr" | "bit" | "bit varying" | "varbit" | "tsvector" | "tsquery" | "uuid" | "xml" | "json" | "jsonb" | "varbinary" | "hierarchyid" | "sql_variant" | "rowid" | "urowid" | "uniqueidentifier" | "rowversion" | "array" | "cube" | "ltree";
/**
 * Any column type column can be.
 */
export type ColumnType = WithPrecisionColumnType | WithLengthColumnType | WithWidthColumnType | SpatialColumnType | SimpleColumnType | BooleanConstructor | DateConstructor | NumberConstructor | StringConstructor;

• name：列名称，可以不指定，默认使用变量名

• length：列长度，通常数据类型为varchar时可用，如varchar(100)

• width：类型占用字节，如int(4)

• nullable：字段是否可为空，默认为false(不可空)

• update：字段只读，通常指是否支持save操作，默认false

• select：是否支持执行QueryBuilder操作，默认为true

• insert：是否支持insert操作，默认为true

• comment：列备注，不是所有类型都支持

• precision： number类型小数点后的位数

• transformer：数据库和实体类之前数据转换配置

• 。。。等等

主键定义

• @PrimaryColumn()：创建一个指定任何类型的数据为主键

import { Entity, PrimaryColumn } from "typeorm"

@Entity()
export class User {
    @PrimaryColumn()
    id: number
}

• @PrimaryGeneratedColumn()：创建一个自增类型的主键，一般为number类型数据，我们不需要对其进行赋值，其会自动生成。

import { Entity, PrimaryGeneratedColumn } from "typeorm";

@Entity()
export class User {
    @PrimaryGeneratedColumn()
    id: number;
}

• @PrimaryGeneratedColumn(“uuid”)：创建一个由uuid自动生成的主键列，Uuid 是一个独特的字符串 id。不需要我们手动分配数据，其会自动生成。

import { Entity, PrimaryGeneratedColumn } from "typeorm";

@Entity()
export class User {
    @PrimaryGeneratedColumn("uuid")
    id: string;
}

特殊列

• @CreateDateColumn ：自动为实体插入日期。无需设置此列，该值将自动设置。

• @UpdateDateColumn：自动更新实体日期。无需设置此列，该值将自动设置。

• @VersionColumn：每次调用实体管理器或存储库的save时自动增长实体版本（增量编号）。无需设置此列，该值将自动设置。

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