typeorm

2019-12-04

typeorm是什么

什么是typeorm,Data-Mapper ORM for TypeScript, ES7, ES6, ES5. Supports MySQL, PostgreSQL, MariaDB, SQLite, MS SQL Server, Oracle, MongoDB databases.

typeorm使用教程帮助文档

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TypeORM is an ORMthat can run in NodeJS, Browser, Cordova, PhoneGap, Ionic, React Native, NativeScript, Expo, and Electron platforms and can be used with TypeScript and JavaScript (ES5, ES6, ES7, ES8). Its goal is to always support the latest JavaScript features and provide additional features that help you to develop any kind of application that uses databases - from small applications with a few tables to large scale enterprise applications with multiple databases.

TypeORM supports both Active Recordand Data Mapperpatterns, unlike all other JavaScript ORMs currently in existence, which means you can write high quality, loosely coupled, scalable, maintainable applications the most productive way.

TypeORM is highly influenced by other ORMs, such as Hibernate, Doctrineand Entity Framework.

Some TypeORM features:

  • supports both DataMapperand ActiveRecord(your choice)
  • entities and columns
  • database-specific column types
  • entity manager
  • repositories and custom repositories
  • clean object relational model
  • associations (relations)
  • eager and lazy relations
  • uni-directional, bi-directional and self-referenced relations
  • supports multiple inheritance patterns
  • cascades
  • indices
  • transactions
  • migrations and automatic migrations generation
  • connection pooling
  • replication
  • using multiple database connections
  • working with multiple databases types
  • cross-database and cross-schema queries
  • elegant-syntax, flexible and powerful QueryBuilder
  • left and inner joins
  • proper pagination for queries using joins
  • query caching
  • streaming raw results
  • logging
  • listeners and subscribers (hooks)
  • supports closure table pattern
  • schema declaration in models or separate configuration files
  • connection configuration in json / xml / yml / env formats
  • supports MySQL / MariaDB / Postgres / CockroachDB / SQLite / Microsoft SQL Server / Oracle / sql.js
  • supports MongoDB NoSQL database
  • works in NodeJS / Browser / Ionic / Cordova / React Native / NativeScript / Expo / Electron platforms
  • TypeScript and JavaScript support
  • produced code is performant, flexible, clean and maintainable
  • follows all possible best practices
  • CLI

And more...

With TypeORM your models look like this:

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

@Entity()
export class User {

    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    firstName: string;

    @Column()
    lastName: string;

    @Column()
    age: number;

}

And your domain logic looks like this:

const user = new User();
user.firstName = "Timber";
user.lastName = "Saw";
user.age = 25;
await repository.save(user);

const allUsers = await repository.find();
const firstUser = await repository.findOne(1); // find by id
const timber = await repository.findOne({ firstName: "Timber", lastName: "Saw" });

await repository.remove(timber);

Alternatively, if you prefer to use the ActiveRecordimplementation, you can use it as well:

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

@Entity()
export class User extends BaseEntity {

    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    firstName: string;

    @Column()
    lastName: string;

    @Column()
    age: number;

}

And your domain logic will look this way:

const user = new User();
user.firstName = "Timber";
user.lastName = "Saw";
user.age = 25;
await user.save();

const allUsers = await User.find();
const firstUser = await User.findOne(1);
const timber = await User.findOne({ firstName: "Timber", lastName: "Saw" });

await timber.remove();

Installation

  1. Install the npm package:

    npm install typeorm --save

  2. You need to install reflect-metadatashim:

    npm install reflect-metadata --save

    and import it somewhere in the global place of your app (for example in app.ts):

    import "reflect-metadata";

  3. You may need to install node typings:

    npm install @types/node --save

  4. Install a database driver:

    • for MySQLor MariaDB

      npm install mysql --save(you can install mysql2instead as well)

    • for PostgreSQLor CockroachDB

      npm install pg --save

    • for SQLite

      npm install sqlite3 --save

    • for Microsoft SQL Server

      npm install mssql --save

    • for sql.js

      npm install sql.js --save

    • for Oracle

      npm install oracledb --save

      Install only oneof them, depending on which database you use.

      To make the Oracle driver work, you need to follow the installation instructions from theirsite.

    • for MongoDB(experimental)

      npm install mongodb --save

    • for NativeScript, react-nativeand Cordova

      Check documentation of supported platforms

TypeScript configuration

Also, make sure you are using TypeScript compiler version 3.3or greater, and you have enabled the following settings in tsconfig.json:

"emitDecoratorMetadata": true,
"experimentalDecorators": true,

You may also need to enable es6in the libsection of compiler options, or install es6-shimfrom @types.

Quick Start

The quickest way to get started with TypeORM is to use its CLI commands to generate a starter project. Quick start works only if you are using TypeORM in a NodeJS application. If you are using other platforms, proceed to the step-by-step guide.

First, install TypeORM globally:

npm install typeorm -g

Then go to the directory where you want to create a new project and run the command:

typeorm init --name MyProject --database mysql

Where nameis the name of your project and databaseis the database you'll use. Database can be one of the following values: mysql, mariadb, postgres, cockroachdb, sqlite, mssql, oracle, mongodb, cordova, react-native, expo, nativescript.

This command will generate a new project in the MyProjectdirectory with the following files:

MyProject
├── src              // place of your TypeScript code
│   ├── entity       // place where your entities (database models) are stored
│   │   └── User.ts  // sample entity
│   ├── migration    // place where your migrations are stored
│   └── index.ts     // start point of your application
├── .gitignore       // standard gitignore file
├── ormconfig.json   // ORM and database connection configuration
├── package.json     // node module dependencies
├── README.md        // simple readme file
└── tsconfig.json    // TypeScript compiler options

You can also run typeorm initon an existing node project, but be careful - it may override some files you already have.

The next step is to install new project dependencies:

cd MyProject
npm install

While installation is in progress, edit the ormconfig.jsonfile and put your own database connection configuration options in there:

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

Particularly, most of the time you'll only need to configure host, username, password, databaseand maybe portoptions.

Once you finish with configuration and all node modules are installed, you can run your application:

npm start

That's it, your application should successfully run and insert a new user into the database. You can continue to work with this project and integrate other modules you need and start creating more entities.

You can generate an even more advanced project with express installed by running typeorm init --name MyProject --database mysql --expresscommand.

Step-by-Step Guide

What are you expecting from ORM? First of all, you are expecting it will create database tables for you and find / insert / update / delete your data without the pain of having to write lots of hardly maintainable SQL queries. This guide will show you how to setup TypeORM from scratch and make it do what you are expecting from an ORM.

Create a model

Working with a database starts from creating tables. How do you tell TypeORM to create a database table? The answer is - through the models. Your models in your app are your database tables.

For example, you have a Photomodel:

export class Photo {
    id: number;
    name: string;
    description: string;
    filename: string;
    views: number;
    isPublished: boolean;
}

And you want to store photos in your database. To store things in the database, first you need a database table, and database tables are created from your models. Not all models, but only those you define as entities.

Create an entity

Entityis your model decorated by an @Entitydecorator. A database table will be created for such models. You work with entities everywhere with TypeORM. You can load/insert/update/remove and perform other operations with them.

Let's make our Photomodel as an entity:

import {Entity} from "typeorm";

@Entity()
export class Photo {
    id: number;
    name: string;
    description: string;
    filename: string;
    views: number;
    isPublished: boolean;
}

Now, a database table will be created for the Photoentity and we'll be able to work with it anywhere in our app. We have created a database table, however what table can exist without columns? Let's create a few columns in our database table.

Adding table columns

To add database columns, you simply need to decorate an entity's properties you want to make into a column with a @Columndecorator.

import {Entity, Column} from "typeorm";

@Entity()
export class Photo {

    @Column()
    id: number;

    @Column()
    name: string;

    @Column()
    description: string;

    @Column()
    filename: string;

    @Column()
    views: number;

    @Column()
    isPublished: boolean;
}

Now id, name, description, filename, viewsand isPublishedcolumns will be added to the phototable. Column types in the database are inferred from the property types you used, e.g. numberwill be converted into integer, stringinto varchar, booleaninto bool, etc. But you can use any column type your database supports by implicitly specifying a column type into the @Columndecorator.

We generated a database table with columns, but there is one thing left. Each database table must have a column with a primary key.

Creating a primary column

Each entity musthave at least one primary key column. This is a requirement and you can't avoid it. To make a column a primary key, you need to use @PrimaryColumndecorator.

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

@Entity()
export class Photo {

    @PrimaryColumn()
    id: number;

    @Column()
    name: string;

    @Column()
    description: string;

    @Column()
    filename: string;

    @Column()
    views: number;

    @Column()
    isPublished: boolean;
}

Creating an auto generated column

Now, let's say you want your id column to be auto-generated (this is known as auto-increment / sequence / serial / generated identity column). To do that, you need to change the @PrimaryColumndecorator to a @PrimaryGeneratedColumndecorator:

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

@Entity()
export class Photo {

    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    name: string;

    @Column()
    description: string;

    @Column()
    filename: string;

    @Column()
    views: number;

    @Column()
    isPublished: boolean;
}

Column data types

Next, let's fix our data types. By default, string is mapped to a varchar(255)-like type (depending on the database type). Number is mapped to a integer-like type (depending on the database type). We don't want all our columns to be limited varchars or integers. Let's setup correct data types:

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

@Entity()
export class Photo {

    @PrimaryGeneratedColumn()
    id: number;

    @Column({
        length: 100
    })
    name: string;

    @Column("text")
    description: string;

    @Column()
    filename: string;

    @Column("double")
    views: number;

    @Column()
    isPublished: boolean;
}

Column types are database-specific. You can set any column type your database supports. More information on supported column types can be found here.

Creating a connection to the database

Now, when our entity is created, let's create an index.ts(or app.tswhatever you call it) file and set up our connection there:

import "reflect-metadata";
import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";

createConnection({
    type: "mysql",
    host: "localhost",
    port: 3306,
    username: "root",
    password: "admin",
    database: "test",
    entities: [
        Photo
    ],
    synchronize: true,
    logging: false
}).then(connection => {
    // here you can start to work with your entities
}).catch(error => console.log(error));

We are using MySQL in this example, but you can use any other supported database. To use another database, simply change the typein the options to the database type you are using: mysql, mariadb, postgres, cockroachdb, sqlite, mssql, oracle, cordova, nativescript, react-native, expo, or mongodb. Also make sure to use your own host, port, username, password and database settings.

We added our Photo entity to the list of entities for this connection. Each entity you are using in your connection must be listed there.

Setting synchronizemakes sure your entities will be synced with the database, every time you run the application.

Loading all entities from the directory

Later, when we create more entities we need to add them to the entities in our configuration. This is not very convenient, so instead we can set up the whole directory, from where all entities will be connected and used in our connection:

import {createConnection} from "typeorm";

createConnection({
    type: "mysql",
    host: "localhost",
    port: 3306,
    username: "root",
    password: "admin",
    database: "test",
    entities: [
        __dirname + "/entity/*.js"
    ],
    synchronize: true,
}).then(connection => {
    // here you can start to work with your entities
}).catch(error => console.log(error));

But be careful with this approach. If you are using ts-nodethen you need to specify paths to .tsfiles instead. If you are using outDirthen you'll need to specify paths to .jsfiles inside outDir directory. If you are using outDirand when you remove or rename your entities make sure to clear outDirdirectory and re-compile your project again, because when you remove your source .tsfiles their compiled .jsversions aren't removed from output directory and still are loaded by TypeORM because they are present in the outDirdirectory.

Running the application

Now if you run your index.ts, a connection with database will be initialized and a database table for your photos will be created.

+-------------+--------------+----------------------------+
|                         photo                           |
+-------------+--------------+----------------------------+
| id          | int(11)      | PRIMARY KEY AUTO_INCREMENT |
| name        | varchar(100) |                            |
| description | text         |                            |
| filename    | varchar(255) |                            |
| views       | int(11)      |                            |
| isPublished | boolean      |                            |
+-------------+--------------+----------------------------+

Creating and inserting a photo into the database

Now let's create a new photo to save it in the database:

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";

createConnection(/*...*/).then(connection => {

    let photo = new Photo();
    photo.name = "Me and Bears";
    photo.description = "I am near polar bears";
    photo.filename = "photo-with-bears.jpg";
    photo.views = 1;
    photo.isPublished = true;

    return connection.manager
            .save(photo)
            .then(photo => {
                console.log("Photo has been saved. Photo id is", photo.id);
            });

}).catch(error => console.log(error));

Once your entity is saved it will get a newly generated id. savemethod returns an instance of the same object you pass to it. It's not a new copy of the object, it modifies its "id" and returns it.

Using async/await syntax

Let's take advantage of the latest ES8 (ES2017) features and use async/await syntax instead:

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";

createConnection(/*...*/).then(async connection => {

    let photo = new Photo();
    photo.name = "Me and Bears";
    photo.description = "I am near polar bears";
    photo.filename = "photo-with-bears.jpg";
    photo.views = 1;
    photo.isPublished = true;

    await connection.manager.save(photo);
    console.log("Photo has been saved");

}).catch(error => console.log(error));

Using Entity Manager

We just created a new photo and saved it in the database. We used EntityManagerto save it. Using entity manager you can manipulate any entity in your app. For example, let's load our saved entity:

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";

createConnection(/*...*/).then(async connection => {

    /*...*/
    let savedPhotos = await connection.manager.find(Photo);
    console.log("All photos from the db: ", savedPhotos);

}).catch(error => console.log(error));

savedPhotoswill be an array of Photo objects with the data loaded from the database.

Learn more about EntityManager here.

Using Repositories

Now let's refactor our code and use Repositoryinstead of EntityManager. Each entity has its own repository which handles all operations with its entity. When you deal with entities a lot, Repositories are more convenient to use than EntityManagers:

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";

createConnection(/*...*/).then(async connection => {

    let photo = new Photo();
    photo.name = "Me and Bears";
    photo.description = "I am near polar bears";
    photo.filename = "photo-with-bears.jpg";
    photo.views = 1;
    photo.isPublished = true;

    let photoRepository = connection.getRepository(Photo);

    await photoRepository.save(photo);
    console.log("Photo has been saved");

    let savedPhotos = await photoRepository.find();
    console.log("All photos from the db: ", savedPhotos);

}).catch(error => console.log(error));

Learn more about Repository here.

Loading from the database

Let's try more load operations using the Repository:

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";

createConnection(/*...*/).then(async connection => {

    /*...*/
    let allPhotos = await photoRepository.find();
    console.log("All photos from the db: ", allPhotos);

    let firstPhoto = await photoRepository.findOne(1);
    console.log("First photo from the db: ", firstPhoto);

    let meAndBearsPhoto = await photoRepository.findOne({ name: "Me and Bears" });
    console.log("Me and Bears photo from the db: ", meAndBearsPhoto);

    let allViewedPhotos = await photoRepository.find({ views: 1 });
    console.log("All viewed photos: ", allViewedPhotos);

    let allPublishedPhotos = await photoRepository.find({ isPublished: true });
    console.log("All published photos: ", allPublishedPhotos);

    let [allPhotos, photosCount] = await photoRepository.findAndCount();
    console.log("All photos: ", allPhotos);
    console.log("Photos count: ", photosCount);

}).catch(error => console.log(error));

Updating in the database

Now let's load a single photo from the database, update it and save it:

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";

createConnection(/*...*/).then(async connection => {

    /*...*/
    let photoToUpdate = await photoRepository.findOne(1);
    photoToUpdate.name = "Me, my friends and polar bears";
    await photoRepository.save(photoToUpdate);

}).catch(error => console.log(error));

Now photo with id = 1will be updated in the database.

Removing from the database

Now let's remove our photo from the database:

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";

createConnection(/*...*/).then(async connection => {

    /*...*/
    let photoToRemove = await photoRepository.findOne(1);
    await photoRepository.remove(photoToRemove);

}).catch(error => console.log(error));

Now photo with id = 1will be removed from the database.

Creating a one-to-one relation

Let's create a one-to-one relation with another class. Let's create a new class in PhotoMetadata.ts. This PhotoMetadata class is supposed to contain our photo's additional meta-information:

import {Entity, Column, PrimaryGeneratedColumn, OneToOne, JoinColumn} from "typeorm";
import {Photo} from "./Photo";

@Entity()
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;
}

Here, we are using a new decorator called @OneToOne. It allows us to create a one-to-one relationship between two entities. type => Photois a function that returns the class of the entity with which we want to make our relationship. We are forced to use a function that returns a class, instead of using the class directly, because of the language specifics. We can also write it as () => Photo, but we use type => Photoas a convention to increase code readability. The type variable itself does not contain anything.

We also add a @JoinColumndecorator, which indicates that this side of the relationship will own the relationship. Relations can be unidirectional or bidirectional. Only one side of relational can be owning. Using @JoinColumndecorator is required on the owner side of the relationship.

If you run the app, you'll see a newly generated table, and it will contain a column with a foreign key for the photo relation:

+-------------+--------------+----------------------------+
|                     photo_metadata                      |
+-------------+--------------+----------------------------+
| id          | int(11)      | PRIMARY KEY AUTO_INCREMENT |
| height      | int(11)      |                            |
| width       | int(11)      |                            |
| comment     | varchar(255) |                            |
| compressed  | boolean      |                            |
| orientation | varchar(255) |                            |
| photoId     | int(11)      | FOREIGN KEY                |
+-------------+--------------+----------------------------+

Save a one-to-one relation

Now let's save a photo, its metadata and attach them to each other.

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";
import {PhotoMetadata} from "./entity/PhotoMetadata";

createConnection(/*...*/).then(async connection => {

    // create a 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;

    // create a photo metadata
    let metadata = new PhotoMetadata();
    metadata.height = 640;
    metadata.width = 480;
    metadata.compressed = true;
    metadata.comment = "cybershoot";
    metadata.orientation = "portait";
    metadata.photo = photo; // this way we connect them

    // get entity repositories
    let photoRepository = connection.getRepository(Photo);
    let metadataRepository = connection.getRepository(PhotoMetadata);

    // first we should save a photo
    await photoRepository.save(photo);

    // photo is saved. Now we need to save a photo metadata
    await metadataRepository.save(metadata);

    // done
    console.log("Metadata is saved, and relation between metadata and photo is created in the database too");

}).catch(error => console.log(error));

Inverse side of the relationship

Relations can be unidirectional or bidirectional. Currently, our relation between PhotoMetadata and Photo is unidirectional. The owner of the relation is PhotoMetadata, and Photo doesn't know anything about PhotoMetadata. This makes it complicated to access PhotoMetadata from the Photo side. To fix this issue we should add an inverse relation, and make relations between PhotoMetadata and Photo bidirectional. Let's modify our entities:

import {Entity, Column, PrimaryGeneratedColumn, OneToOne, JoinColumn} from "typeorm";
import {Photo} from "./Photo";

@Entity()
export class PhotoMetadata {

    /* ... other columns */

    @OneToOne(type => Photo, photo => photo.metadata)
    @JoinColumn()
    photo: Photo;
}
import {Entity, Column, PrimaryGeneratedColumn, OneToOne} from "typeorm";
import {PhotoMetadata} from "./PhotoMetadata";

@Entity()
export class Photo {

    /* ... other columns */

    @OneToOne(type => PhotoMetadata, photoMetadata => photoMetadata.photo)
    metadata: PhotoMetadata;
}

photo => photo.metadatais a function that returns the name of the inverse side of the relation. Here we show that the metadata property of the Photo class is where we store PhotoMetadata in the Photo class. Instead of passing a function that returns a property of the photo, you could alternatively simply pass a string to @OneToOnedecorator, like "metadata". But we used this function-typed approach to make our refactoring easier.

Note that we should use @JoinColumndecorator only on one side of a relation. Whichever side you put this decorator on will be the owning side of the relationship. The owning side of a relationship contains a column with a foreign key in the database.

Loading objects with their relations

Now let's load our photo and its photo metadata in a single query. There are two ways to do it - using find*methods or using QueryBuilderfunctionality. Let's use find*methods first. find*methods allow you to specify an object with the FindOneOptions/ FindManyOptionsinterface.

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({ relations: ["metadata"] });

}).catch(error => console.log(error));

Here, photos will contain an array of photos from the database, and each photo will contain its photo metadata. Learn more about Find Options in this documentation.

Using find options is good and dead simple, but if you need a more complex query, you should use QueryBuilderinstead. QueryBuilderallows more complex queries to be used in an elegant way:

import {createConnection} from "typeorm";
import {Photo} from "./entity/Photo";
import {PhotoMetadata} from "./entity/PhotoMetadata";

createConnection(/*...*/).then(async connection => {

    /*...*/
    let photos = await connection
            .getRepository(Photo)
            .createQueryBuilder("photo")
            .innerJoinAndSelect("photo.metadata", "metadata")
            .getMany();

}).catch(error => console.log(error));

QueryBuilderallows creation and execution of SQL queries of almost any complexity. When you work with QueryBuilder, think like you are creating an SQL query. In this example, "photo" and "metadata" are aliases applied to selected photos. You use aliases to access columns and properties of the selected data.

Using cascades to automatically save related objects

We can setup cascade options in our relations, in the cases when we want our related object to be saved whenever the other object is saved. Let's change our photo's @OneToOnedecorator a bit:

export class Photo {
    /// ... other columns

    @OneToOne(type => PhotoMetadata, metadata => metadata.photo, {
        cascade: true,
    })
    metadata: PhotoMetadata;
}

Using cascadeallows us not to separately save photo and separately save metadata objects now. Now we can simply save a photo object, and the metadata object will be saved automatically because of cascade options.

createConnection(options).then(async connection => {

    // create photo object
    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;

    // create photo metadata object
    let metadata = new PhotoMetadata();
    metadata.height = 640;
    metadata.width = 480;
    metadata.compressed = true;
    metadata.comment = "cybershoot";
    metadata.orientation = "portait";

    photo.metadata = metadata; // this way we connect them

    // get repository
    let photoRepository = connection.getRepository(Photo);

    // saving a photo also save the metadata
    await photoRepository.save(photo);

    console.log("Photo is saved, photo metadata is saved too.")

}).catch(error => console.log(error));

Creating a many-to-one / one-to-many relation

Let's create a many-to-one / one-to-many relation. Let's say a photo has one author, and each author can have many photos. First, let's create an Authorclass:

import {Entity, Column, PrimaryGeneratedColumn, OneToMany, JoinColumn} from "typeorm";
import {Photo} from "./Photo";

@Entity()
export class Author {

    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    name: string;

    @OneToMany(type => Photo, photo => photo.author) // note: we will create author property in the Photo class below
    photos: Photo[];
}

Authorcontains an inverse side of a relation. OneToManyis always an inverse side of relation, and it can't exist without ManyToOneon the other side of the relation.

Now let's add the owner side of the relation into the Photo entity:

import {Entity, Column, PrimaryGeneratedColumn, ManyToOne} from "typeorm";
import {PhotoMetadata} from "./PhotoMetadata";
import {Author} from "./Author";

@Entity()
export class Photo {

    /* ... other columns */

    @ManyToOne(type => Author, author => author.photos)
    author: Author;
}

In many-to-one / one-to-many relation, the owner side is always many-to-one. It means that the class that uses @ManyToOnewill store the id of the related object.

After you run the application, the ORM will create the authortable:

+-------------+--------------+----------------------------+
|                          author                         |
+-------------+--------------+----------------------------+
| id          | int(11)      | PRIMARY KEY AUTO_INCREMENT |
| name        | varchar(255) |                            |
+-------------+--------------+----------------------------+

It will also modify the phototable, adding a new authorcolumn and creating a foreign key for it:

+-------------+--------------+----------------------------+
|                         photo                           |
+-------------+--------------+----------------------------+
| id          | int(11)      | PRIMARY KEY AUTO_INCREMENT |
| name        | varchar(255) |                            |
| description | varchar(255) |                            |
| filename    | varchar(255) |                            |
| isPublished | boolean      |                            |
| authorId    | int(11)      | FOREIGN KEY                |
+-------------+--------------+----------------------------+

Creating a many-to-many relation

Let's create a many-to-one / many-to-many relation. Let's say a photo can be in many albums, and each album can contain many photos. Let's create an Albumclass:

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

@Entity()
export class Album {

    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    name: string;

    @ManyToMany(type => Photo, photo => photo.albums)
    @JoinTable()
    photos: Photo[];
}

@JoinTableis required to specify that this is the owner side of the relationship.

Now let's add the inverse side of our relation to the Photoclass:

export class Photo {
    /// ... other columns

    @ManyToMany(type => Album, album => album.photos)
    albums: Album[];
}

After you run the application, the ORM will create a album_photos_photo_albums_junction table_:

+-------------+--------------+----------------------------+
|                album_photos_photo_albums                |
+-------------+--------------+----------------------------+
| album_id    | int(11)      | PRIMARY KEY FOREIGN KEY    |
| photo_id    | int(11)      | PRIMARY KEY FOREIGN KEY    |
+-------------+--------------+----------------------------+

Don't forget to register the Albumclass with your connection in the ORM:

const options: ConnectionOptions = {
    // ... other options
    entities: [Photo, PhotoMetadata, Author, Album]
};

Now let's insert albums and photos to our database:

let connection = await createConnection(options);

// create a few albums
let album1 = new Album();
album1.name = "Bears";
await connection.manager.save(album1);

let album2 = new Album();
album2.name = "Me";
await connection.manager.save(album2);

// create a few photos
let photo = new Photo();
photo.name = "Me and Bears";
photo.description = "I am near polar bears";
photo.filename = "photo-with-bears.jpg";
photo.albums = [album1, album2];
await connection.manager.save(photo);

// now our photo is saved and albums are attached to it
// now lets load them:
const loadedPhoto = await connection
    .getRepository(Photo)
    .findOne(1, { relations: ["albums"] });

loadedPhotowill be equal to:

{
    id: 1,
    name: "Me and Bears",
    description: "I am near polar bears",
    filename: "photo-with-bears.jpg",
    albums: [{
        id: 1,
        name: "Bears"
    }, {
        id: 2,
        name: "Me"
    }]
}

Using QueryBuilder

You can use QueryBuilder to build SQL queries of almost any complexity. For example, you can do this:

let photos = await connection
    .getRepository(Photo)
    .createQueryBuilder("photo") // first argument is an alias. Alias is what you are selecting - photos. You must specify it.
    .innerJoinAndSelect("photo.metadata", "metadata")
    .leftJoinAndSelect("photo.albums", "album")
    .where("photo.isPublished = true")
    .andWhere("(photo.name = :photoName OR photo.name = :bearName)")
    .orderBy("photo.id", "DESC")
    .skip(5)
    .take(10)
    .setParameters({ photoName: "My", bearName: "Mishka" })
    .getMany();

This query selects all published photos with "My" or "Mishka" names. It will select results from position 5 (pagination offset), and will select only 10 results (pagination limit). The selection result will be ordered by id in descending order. The photo's albums will be left-joined and their metadata will be inner joined.

You'll use the query builder in your application a lot. Learn more about QueryBuilder here.

Samples

Take a look at the samples in samplefor examples of usage.

There are a few repositories which you can clone and start with:

Extensions

There are several extensions that simplify working with TypeORM and integrating it with other modules:

Contributing

Learn about contribution hereand how to setup your development environment here.

This project exists thanks to all the people who contribute:

Sponsors

Open source is hard and time-consuming. If you want to invest into TypeORM's future you can become a sponsor and make our core team to spend more time on TypeORM's improvements and new features. Become a sponsor

Gold Sponsors

Become a gold sponsor and get a premium technical support from our core contributors. Become a gold sponsor


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