Database subscribers

TypeORM allows us to define subscribers. With a subscriber, we can listen to specific entity events and take actions based on inserts, updates, deletions and more.

If you need lower-level access to database changes that you get with the Vendure EventBus system, TypeORM subscribers can be useful.

Simple subscribers

The simplest way to register a subscriber is to pass it to the dbConnectionOptions.subscribers array:

src/plugins/my-plugin/product-subscriber.ts

import { Product, VendureConfig } from '@vendure/core';import { EntitySubscriberInterface, EventSubscriber, UpdateEvent } from 'typeorm';@EventSubscriber()export class ProductSubscriber implements EntitySubscriberInterface<Product> {  listenTo() {    return Product;  }    beforeUpdate(event: UpdateEvent<Product>) {    console.log(`BEFORE PRODUCT UPDATED: `, event.entity);  }}

src/vendure-config.ts

import { VendureConfig } from '@vendure/core';import { ProductSubscriber } from './plugins/my-plugin/product-subscriber';// ...export const config: VendureConfig = {  dbConnectionOptions: {    // ...    subscribers: [ProductSubscriber],  }}

The limitation of this method is that the ProductSubscriber class cannot make use of dependency injection, since it is not known to the underlying NestJS application and is instead instantiated by TypeORM directly.

If you need to make use of providers in your subscriber class, you'll need to use the following pattern.

Injectable subscribers

By defining the subscriber as an injectable provider, and passing it to a Vendure plugin, you can take advantage of Nest's dependency injection inside the subscriber methods.

src/plugins/my-plugin/product-subscriber.ts

import {  PluginCommonModule,  Product,  TransactionalConnection,  VendureConfig,  VendurePlugin,} from '@vendure/core';import { Injectable } from '@nestjs/common';import { EntitySubscriberInterface, EventSubscriber, UpdateEvent } from 'typeorm';import { MyService } from './services/my.service';@Injectable()@EventSubscriber()export class ProductSubscriber implements EntitySubscriberInterface<Product> {    constructor(private connection: TransactionalConnection,                private myService: MyService) {        // This is how we can dynamically register the subscriber        // with TypeORM        connection.rawConnection.subscribers.push(this);    }    listenTo() {        return Product;    }    async beforeUpdate(event: UpdateEvent<Product>) {        console.log(`BEFORE PRODUCT UPDATED: `, event.entity);        // Now we can make use of our injected provider        await this.myService.handleProductUpdate(event);    }}

Simple subscribers

The simplest way to register a subscriber is to pass it to the dbConnectionOptions.subscribers array:

src/plugins/my-plugin/product-subscriber.ts

import { Product, VendureConfig } from '@vendure/core';import { EntitySubscriberInterface, EventSubscriber, UpdateEvent } from 'typeorm';@EventSubscriber()export class ProductSubscriber implements EntitySubscriberInterface<Product> {  listenTo() {    return Product;  }    beforeUpdate(event: UpdateEvent<Product>) {    console.log(`BEFORE PRODUCT UPDATED: `, event.entity);  }}

src/vendure-config.ts

import { VendureConfig } from '@vendure/core';import { ProductSubscriber } from './plugins/my-plugin/product-subscriber';// ...export const config: VendureConfig = {  dbConnectionOptions: {    // ...    subscribers: [ProductSubscriber],  }}

If you need to make use of providers in your subscriber class, you'll need to use the following pattern.

Injectable subscribers

By defining the subscriber as an injectable provider, and passing it to a Vendure plugin, you can take advantage of Nest's dependency injection inside the subscriber methods.

src/plugins/my-plugin/product-subscriber.ts

import {  PluginCommonModule,  Product,  TransactionalConnection,  VendureConfig,  VendurePlugin,} from '@vendure/core';import { Injectable } from '@nestjs/common';import { EntitySubscriberInterface, EventSubscriber, UpdateEvent } from 'typeorm';import { MyService } from './services/my.service';@Injectable()@EventSubscriber()export class ProductSubscriber implements EntitySubscriberInterface<Product> {    constructor(private connection: TransactionalConnection,                private myService: MyService) {        // This is how we can dynamically register the subscriber        // with TypeORM        connection.rawConnection.subscribers.push(this);    }    listenTo() {        return Product;    }    async beforeUpdate(event: UpdateEvent<Product>) {        console.log(`BEFORE PRODUCT UPDATED: `, event.entity);        // Now we can make use of our injected provider        await this.myService.handleProductUpdate(event);    }}

Database subscribers

Simple subscribers

Injectable subscribers

Database subscribers

Simple subscribers

Injectable subscribers

Troubleshooting subscribers