TypeORM is anORM that can run in NodeJS, Browser, Cordova, PhoneGap, Ionic, React Native, NativeScript, Expo, and Electron platforms and can be used with TypeScript and JavaScript (ES2021). 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 bothActive RecordandData Mapperpatterns, unlike all other JavaScript ORMs currently in existence, which means you can write high-quality, loosely coupled, scalable, maintainable applications in the most productive way.

TypeORM is highly influenced by other ORMs, such asHibernate, DoctrineandEntity Framework.

Features

• Supports bothDataMapperandActiveRecord(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 instances.
• Working with multiple database 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.
• Supports MySQL / MariaDB / Postgres / CockroachDB / SQLite / Microsoft SQL Server / Oracle / SAP Hana / sql.js.
• Supports MongoDB NoSQL database.
• Works in NodeJS / Browser / Ionic / Cordova / React Native / NativeScript / Expo / Electron platforms.
• TypeScript and JavaScript support.
• ESM and CommonJS 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()
exportclassUser{
@PrimaryGeneratedColumn()
id:number

@Column()
firstName:string

@Column()
lastName:string

@Column()
age:number
}

And your domain logic looks like this:

constuserRepository=MyDataSource.getRepository(User)

constuser=newUser()
user.firstName="Timber"
user.lastName="Saw"
user.age=25
awaituserRepository.save(user)

constallUsers=awaituserRepository.find()
constfirstUser=awaituserRepository.findOneBy({
id:1,
})// find by id
consttimber=awaituserRepository.findOneBy({
firstName:"Timber",
lastName:"Saw",
})// find by firstName and lastName

awaituserRepository.remove(timber)

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

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

@Entity()
exportclassUserextendsBaseEntity{
@PrimaryGeneratedColumn()
id:number

@Column()
firstName:string

@Column()
lastName:string

@Column()
age:number
}

And your domain logic will look this way:

constuser=newUser()
user.firstName="Timber"
user.lastName="Saw"
user.age=25
awaituser.save()

constallUsers=awaitUser.find()
constfirstUser=awaitUser.findOneBy({
id:1,
})
consttimber=awaitUser.findOneBy({
firstName:"Timber",
lastName:"Saw"
})

awaittimber.remove()

Installation

1. Install the npm package:

   npm install typeorm --save

2. You need to installreflect-metadatashim:

   npm install reflect-metadata --save

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

   import "reflect-metadata"

3. You may need to install node typings:

   npm install @types/node --save-dev

4. Install a database driver:

   • forMySQLorMariaDB

     npm install mysql --save(you can installmysql2instead as well)

   • forPostgreSQLorCockroachDB

     npm install pg --save

   • forSQLite

     npm install sqlite3 --save

   • forMicrosoft SQL Server

     npm install mssql --save

   • forsql.js

     npm install sql.js --save

   • forOracle

     npm install oracledb --save

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

   • forSAP Hana

     npm install @sap/hana-client
     npm install hdb-pool
     

     SAP Hana support made possible by the sponsorship ofNeptune Software.

   • forGoogle Cloud Spanner

     npm install @google-cloud/spanner --save
     

     Provide authentication credentials to your application code by setting the environment variableGOOGLE_APPLICATION_CREDENTIALS:

     #Linux/macOS
     exportGOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"
     
     #Windows
     setGOOGLE_APPLICATION_CREDENTIALS=KEY_PATH
     
     #Replace KEY_PATH with the path of the JSON file that contains your service account key.

     To use Spanner with the emulator you should setSPANNER_EMULATOR_HOSTenvironment variable:

     #Linux/macOS
     exportSPANNER_EMULATOR_HOST=localhost:9010
     
     #Windows
     setSPANNER_EMULATOR_HOST=localhost:9010

   • forMongoDB(experimental)

     npm install mongodb@^5.2.0 --save

   • forNativeScript,react-nativeandCordova

     Checkdocumentation of supported platforms

   Install onlyoneof them, depending on which database you use.

TypeScript configuration

Also, make sure you are using TypeScript version4.5or higher, and you have enabled the following settings intsconfig.json:

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

You may also need to enablees6in thelibsection of compiler options, or installes6-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 thestep-by-step guide.

To create a new project using CLI, run the following command:

npx typeorm init --name MyProject --database postgres

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

This command will generate a new project in theMyProjectdirectory 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
│ ├── data-source.ts // data source and all connection configuration
│ └── index.ts // start point of your application
├──.gitignore // standard gitignore file
├── package.json // node module dependencies
├── README.md // simple readme file
└── tsconfig.json // TypeScript compiler options

You can also runtypeorm 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:

cdMyProject
npm install

After you have all dependencies installed, edit thedata-source.tsfile and put your own database connection configuration options in there:

exportconstAppDataSource=newDataSource({
type:"postgres",
host:"localhost",
port:5432,
username:"test",
password:"test",
database:"test",
synchronize:true,
logging:true,
entities:[Post,Category],
subscribers:[],
migrations:[],
})

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

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 ESM project by running npx typeorm init --name MyProject --database postgres --module esmcommand.

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

You can generate a docker-compose file by running npx typeorm init --name MyProject --database postgres --dockercommand.

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 set up TypeORM from scratch and make it do what you are expecting from an ORM.

Create a model

Working with a database starts with 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 aPhotomodel:

exportclassPhoto{
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 asentities.

Create an entity

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

Let's make ourPhotomodel an entity:

import{Entity}from"typeorm"

@Entity()
exportclassPhoto{
id:number
name:string
description:string
filename:string
views:number
isPublished:boolean
}

Now, a database table will be created for thePhotoentity 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()
exportclassPhoto{
@Column()
id:number

@Column()
name:string

@Column()
description:string

@Column()
filename:string

@Column()
views:number

@Column()
isPublished:boolean
}

Nowid,name,description,filename,views,andisPublishedcolumns will be added to thephototable. Column types in the database are inferred from the property types you used, e.g. numberwill be converted intointeger,stringintovarchar,booleanintobool,etc. But you can use any column type your database supports by explicitly 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 entitymusthave 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 the@PrimaryColumndecorator.

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

@Entity()
exportclassPhoto{
@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()
exportclassPhoto{
@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, the string is mapped to a varchar(255)-like type (depending on the database type). The number is mapped to an integer-like type (depending on the database type). We don't want all our columns to be limited varchars or integers. Let's setup the correct data types:

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

@Entity()
exportclassPhoto{
@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 foundhere.

Creating a newDataSource

Now, when our entity is created, let's createindex.tsfile and set up ourDataSourcethere:

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

constAppDataSource=newDataSource({
type:"postgres",
host:"localhost",
port:5432,
username:"root",
password:"admin",
database:"test",
entities:[Photo],
synchronize:true,
logging:false,
})

// to initialize the initial connection with the database, register all entities
// and "synchronize" database schema, call "initialize()" method of a newly created database
// once in your application bootstrap
AppDataSource.initialize()
.then(()=>{
// here you can start to work with your database
})
.catch((error)=>console.log(error))

We are using Postgres in this example, but you can use any other supported database. To use another database, simply change thetypein the options to the database type you are using: mysql,mariadb,postgres,cockroachdb,sqlite,mssql,oracle,sap,spanner,cordova,nativescript,react-native, expo,ormongodb. 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 data source. Each entity you are using in your connection must be listed there.

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

Running the application

Now if you run yourindex.ts,a connection with the 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{Photo}from"./entity/Photo"
import{AppDataSource}from"./index"

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

awaitAppDataSource.manager.save(photo)
console.log("Photo has been saved. Photo id is",photo.id)

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 Entity Manager

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

import{Photo}from"./entity/Photo"
import{AppDataSource}from"./index"

constsavedPhotos=awaitAppDataSource.manager.find(Photo)
console.log("All photos from the db:",savedPhotos)

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

Learn more about EntityManagerhere.

Using Repositories

Now let's refactor our code and useRepositoryinstead ofEntityManager. 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{Photo}from"./entity/Photo"
import{AppDataSource}from"./index"

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

constphotoRepository=AppDataSource.getRepository(Photo)

awaitphotoRepository.save(photo)
console.log("Photo has been saved")

constsavedPhotos=awaitphotoRepository.find()
console.log("All photos from the db:",savedPhotos)

Learn more about Repositoryhere.

Loading from the database

Let's try more load operations using the Repository:

import{Photo}from"./entity/Photo"
import{AppDataSource}from"./index"

constphotoRepository=AppDataSource.getRepository(Photo)
constallPhotos=awaitphotoRepository.find()
console.log("All photos from the db:",allPhotos)

constfirstPhoto=awaitphotoRepository.findOneBy({
id:1,
})
console.log("First photo from the db:",firstPhoto)

constmeAndBearsPhoto=awaitphotoRepository.findOneBy({
name:"Me and Bears",
})
console.log("Me and Bears photo from the db:",meAndBearsPhoto)

constallViewedPhotos=awaitphotoRepository.findBy({views:1})
console.log("All viewed photos:",allViewedPhotos)

constallPublishedPhotos=awaitphotoRepository.findBy({isPublished:true})
console.log("All published photos:",allPublishedPhotos)

const[photos,photosCount]=awaitphotoRepository.findAndCount()
console.log("All photos:",photos)
console.log("Photos count:",photosCount)

Updating in the database

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

import{Photo}from"./entity/Photo"
import{AppDataSource}from"./index"

constphotoRepository=AppDataSource.getRepository(Photo)
constphotoToUpdate=awaitphotoRepository.findOneBy({
id:1,
})
photoToUpdate.name="Me, my friends and polar bears"
awaitphotoRepository.save(photoToUpdate)

Now photo withid = 1will be updated in the database.

Removing from the database

Now let's remove our photo from the database:

import{Photo}from"./entity/Photo"
import{AppDataSource}from"./index"

constphotoRepository=AppDataSource.getRepository(Photo)
constphotoToRemove=awaitphotoRepository.findOneBy({
id:1,
})
awaitphotoRepository.remove(photoToRemove)

Now photo withid = 1will be removed from the database.

Creating a one-to-one relation

Let's create a one-to-one relationship with another class. Let's create a new class inPhotoMetadata.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()
exportclassPhotoMetadata{
@PrimaryGeneratedColumn()
id:number

@Column("int")
height:number

@Column("int")
width:number

@Column()
orientation:string

@Column()
compressed:boolean

@Column()
comment:string

@OneToOne(()=>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 usetype => 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, and its metadata and attach them to each other.

import{Photo}from"./entity/Photo"
import{PhotoMetadata}from"./entity/PhotoMetadata"

// create a photo
constphoto=newPhoto()
photo.name="Me and Bears"
photo.description="I am near polar bears"
photo.filename="photo-with-bears.jpg"
photo.views=1
photo.isPublished=true

// create a photo metadata
constmetadata=newPhotoMetadata()
metadata.height=640
metadata.width=480
metadata.compressed=true
metadata.comment="cybershoot"
metadata.orientation="portrait"
metadata.photo=photo// this way we connect them

// get entity repositories
constphotoRepository=AppDataSource.getRepository(Photo)
constmetadataRepository=AppDataSource.getRepository(PhotoMetadata)

// first we should save a photo
awaitphotoRepository.save(photo)

// photo is saved. Now we need to save a photo metadata
awaitmetadataRepository.save(metadata)

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

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()
exportclassPhotoMetadata{
/*... other columns */

@OneToOne(()=>Photo,(photo)=>photo.metadata)
@JoinColumn()
photo:Photo
}

import{Entity,Column,PrimaryGeneratedColumn,OneToOne}from"typeorm"
import{PhotoMetadata}from"./PhotoMetadata"

@Entity()
exportclassPhoto{
/*... other columns */

@OneToOne(()=>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 the@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.

Relations in ESM projects

If you use ESM in your TypeScript project, you should use theRelationwrapper type in relation properties to avoid circular dependency issues. Let's modify our entities:

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

@Entity()
exportclassPhotoMetadata{
/*... other columns */

@OneToOne(()=>Photo,(photo)=>photo.metadata)
@JoinColumn()
photo:Relation<Photo>
}

import{
Entity,
Column,
PrimaryGeneratedColumn,
OneToOne,
Relation,
}from"typeorm"
import{PhotoMetadata}from"./PhotoMetadata"

@Entity()
exportclassPhoto{
/*... other columns */

@OneToOne(()=>PhotoMetadata,(photoMetadata)=>photoMetadata.photo)
metadata:Relation<PhotoMetadata>
}

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 - usingfind*methods or usingQueryBuilderfunctionality. Let's usefind*method first. find*methods allow you to specify an object with theFindOneOptions/FindManyOptionsinterface.

import{Photo}from"./entity/Photo"
import{PhotoMetadata}from"./entity/PhotoMetadata"
import{AppDataSource}from"./index"

constphotoRepository=AppDataSource.getRepository(Photo)
constphotos=awaitphotoRepository.find({
relations:{
metadata:true,
},
})

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

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

import{Photo}from"./entity/Photo"
import{PhotoMetadata}from"./entity/PhotoMetadata"
import{AppDataSource}from"./index"

constphotos=awaitAppDataSource.getRepository(Photo)
.createQueryBuilder("photo")
.innerJoinAndSelect("photo.metadata","metadata")
.getMany()

QueryBuilderallows the creation and execution of SQL queries of almost any complexity. When you work withQueryBuilder,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 set up 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:

exportclassPhoto{
//... other columns

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

Usingcascadeallows us not to separately save photos 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.

import{AppDataSource}from"./index"

// create photo object
constphoto=newPhoto()
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
constmetadata=newPhotoMetadata()
metadata.height=640
metadata.width=480
metadata.compressed=true
metadata.comment="cybershoot"
metadata.orientation="portrait"

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

// get repository
constphotoRepository=AppDataSource.getRepository(Photo)

// saving a photo also save the metadata
awaitphotoRepository.save(photo)

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

Notice that we now set the photo'smetadataproperty, instead of the metadata'sphotoproperty as before. Thecascadefeature only works if you connect the photo to its metadata from the photo's side. If you set the metadata side, the metadata would not be saved automatically.

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 anAuthorclass:

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

@Entity()
exportclassAuthor{
@PrimaryGeneratedColumn()
id:number

@Column()
name:string

@OneToMany(()=>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 the relation, and it can't exist withoutManyToOneon 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()
exportclassPhoto{
/*... other columns */

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

In many-to-one / one-to-many relations, 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 theauthortable:

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

It will also modify thephototable, adding a newauthorcolumn 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-many relation. Let's say a photo can be in many albums, and each album can contain many photos. Let's create anAlbumclass:

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

@Entity()
exportclassAlbum{
@PrimaryGeneratedColumn()
id:number

@Column()
name:string

@ManyToMany(()=>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 thePhotoclass:

exportclassPhoto{
//... other columns

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

After you run the application, the ORM will create aalbum_photos_photo_albumsjunction 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 theAlbumclass with your connection in the ORM:

constoptions:DataSourceOptions={
//... other options
entities:[Photo,PhotoMetadata,Author,Album],
}

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

import{AppDataSource}from"./index"

// create a few albums
constalbum1=newAlbum()
album1.name="Bears"
awaitAppDataSource.manager.save(album1)

constalbum2=newAlbum()
album2.name="Me"
awaitAppDataSource.manager.save(album2)

// create a few photos
constphoto=newPhoto()
photo.name="Me and Bears"
photo.description="I am near polar bears"
photo.filename="photo-with-bears.jpg"
photo.views=1
photo.isPublished=true
photo.albums=[album1,album2]
awaitAppDataSource.manager.save(photo)

// now our photo is saved and albums are attached to it
// now lets load them:
constloadedPhoto=awaitAppDataSource.getRepository(Photo).findOne({
where:{
id:1,
},
relations:{
albums:true,
},
})

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:

constphotos=awaitAppDataSource.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 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 QueryBuilderhere.

Samples

Take a look at the samples insamplefor examples of usage.

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

• Example how to use TypeORM with TypeScript
• Example how to use TypeORM with JavaScript
• Example how to use TypeORM with JavaScript and Babel
• Example how to use TypeORM with TypeScript and SystemJS in Browser
• Example how to use TypeORM with TypeScript and React in Browser
• Example how to use Express and TypeORM
• Example how to use Koa and TypeORM
• Example how to use TypeORM with MongoDB
• Example how to use TypeORM in a Cordova/PhoneGap app
• Example how to use TypeORM with an Ionic app
• Example how to use TypeORM with React Native
• Example how to use TypeORM with Nativescript-Vue
• Example how to use TypeORM with Nativescript-Angular
• Example how to use TypeORM with Electron using JavaScript
• Example how to use TypeORM with Electron using TypeScript

Extensions

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

• TypeORM + GraphQL framework
• TypeORM integrationwithTypeDI
• TypeORM integrationwithrouting-controllers
• Models generation from the existing database -typeorm-model-generator
• Fixtures loader -typeorm-fixtures-cli
• ER Diagram generator -typeorm-uml
• another ER Diagram generator -erdia
• Create, drop & seed database -typeorm-extension
• Automatically updatedata-source.tsafter generating migrations/entities -typeorm-codebase-sync
• Easy manipulation ofrelationsobjects -typeorm-relations
• Automatically generaterelationsbased on a GraphQL query -typeorm-relations-graphql

Contributing

Learn about contributionhereand how to set up your development environmenthere.

This project exists thanks to all the people who contribute:

Sponsors

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