NestJS DynamoDB

Description

Opinated way to use DynamoDB with NestJS and typescript, heavily inspired by nestjs-typed-dynamodb

Getting Started

First install this module

npm install @omersalkanovic/nestjs-dynamodb

Notice that it will install dynamodb-data-mapper-annotations as a dependency

Usage

In order to create a DynamoDB connection

app.module.ts

import { Module } from '@nestjs/common'
import { TypegooseModule } from 'nestjs-typed-dynamodb'
import { CatsModule } from './cat.module.ts'

@Module({
  imports: [
    DynamoDBModule.forRoot({
      AWSConfig: {
        region: 'local',
        accessKeyId: 'null',
        secretAccessKey: 'null',
      },
      dynamoDBOptions: {
        endpoint: 'localhost:8000',
        sslEnabled: false,
        region: 'local-env',
      },
    }),
    CatsModule,
  ],
})
export class ApplicationModule {}

To insert records to Dynamo, you first need to create your table, for this we use dynamodb-data-mapper-annotations (under the hood). Every decorator in that package is exposed in this package as well BUT CAPITALIZED .

cat.schema.ts

import {
  Attribute,
  AutoGeneratedHashKey,
  RangeKey,
  Table,
  VersionAttribute,
} from '@omersalkanovic/nestjs-dynamodb'
import * as nanoid from 'nanoid'

@Table('cat')
class Cat {
  @RangeKey({ defaultProvider: nanoid })
  id: string

  @HashKey()
  breed: string

  @Attribute()
  age: number

  @Attribute()
  alive?: boolean

  // This property will not be saved to DynamoDB.
  notPersistedToDynamoDb: string
}

Note: nanoid is only used a way to assign a random id, feel free to use whatever you want

cats.service.ts

import { Injectable } from '@nestjs/common'
import { ReturnModel, InjectModel, OR } from '@omersalkanovic/nestjs-dynamodb'
import { Cat } from './cat.schema'
import { CatInput } from './cat.input'

const ReturnModel = ReturnModel<Cat>()

@Injectable()
export class CatsService {
  constructor(
    @InjectModel(Cat)
    private readonly catModel: typeof ReturnModel,
  ) {}

  async findAll(): Promise<Cat[]> {
    return this.catModel.find()
  }

  async findById(id: string): Promise<Cat> {
    return this.catModel.findById(id)
  }

  async create(input: CatInput): Promise<Cat> {
    return this.catModel.create(input)
  }

  async delete(input: string): Promise<DynamoDB.DeleteItemOutput> {
    return this.catModel.findByIdAndDelete(input)
  }

  async update(id: string, item: CatInput): Promise<Cat> {
    return this.catModel.findByIdAndUpdate(id, item)
  }

  async find(input: Partial<CatInput>): Promise<Cat[]> {
    return this.catModel.find(input);


  }
}

Now its to much easily to query through dynamoDB If you have arrays and different objects

  async find(input: Partial<CatInput>): Promise<Cat[]> {
    return this.catModel.find({alive: true, age: OR(19)});
    // {
    //   TableName: 'cat',
    //   ExpressionAttributeValues: {
    //     ':aliveValue': { BOOL: true },
    //     ':ageValue': { N: 19 },
    //   },
    //   FilterExpression: 'alive = :aliveValue OR age = :ageValue'
    // }

    async find(input: Partial<CatInput>): Promise<Cat[]> {
    return this.catModel.find({alive: true, age: [10, 12]});
    // {
    //   TableName: 'cat',
    //   ExpressionAttributeValues: {
    //     ':aliveValue': { BOOL: true },
    //     ':ageValue0': { N: 10 },
    //     ':ageValue1': { N: 12 },
    //   },
    //   FilterExpression: 'alive = :aliveValue AND (age = :ageValue0 OR age = :ageValue1)'
    // }
  }

Now you can use your service as you wish!

Async configuration

app.module.ts

import { Module } from '@nestjs/common'
import { TypegooseModule } from 'nestjs-typegoose'
import { Cats } from './cat.schema'

@Module({
  imports: [
    DynamoDBModule.forRootAsync({
      imports: [ConfigModule],
      useFactory: async (config: ConfigService) => ({
        AWSConfig: {
          region: 'local',
          accessKeyId: 'null',
          secretAccessKey: 'null',
        },
        dynamoDBOptions: {
          endpoint: config.get<string>('DYNAMODB_URL', 'localhost:8000'),
          sslEnabled: false,
          region: 'local-env',
        },
      }),
      inject: [ConfigService],
    }),
  ],
})
export class ApplicationModule {}