cassandra-for-nest

Cassandra wrapper for nestjs based on cassandra-driver package.

Install

use npm:

npm i cassandra-for-nest --save

Usage

Entity Definition

use @Entity and @Column decorator define an entity:

// device.entity.ts
import { Column, Entity } from "cassandra-for-nest";

@Entity({
    keyspace: 'test',
    table: 'device'
})
export default class Device {
    @Column({name: 'serial_number'})
    serialNumber: string;

    @Column({name: 'create_time'})
    createTime: Date;

    @Column()
    version: string;

    @Column({name: 'is_online'})
    isOnline: boolean;
}

Module Definition

Just like typeorm, you can use forRoot method to configure the database and use forFeature method to register entities:

// cassandra.test.module.ts
import { Module } from "@nestjs/common";
import { auth } from "cassandra-driver";

import { CassandraModule } from "cassandra-for-nest;
import DeviceController from "device.controller";
import Device from "device.entity";
import DeviceService from "device.service";

@Module({
    imports: [
        CassandraModule.forRoot({ // database configuration
            contactPoints: ['localhost'],
            authProvider: new auth.PlainTextAuthProvider('username', 'password'),
            localDataCenter: 'datacenter1'
        }),
        CassandraModule.forFeature([ // register entities
            Device
        ])
    ],
    controllers: [DeviceController], // related controller
    providers: [DeviceService] // related service
})
export default class CassandraTestModule {}

Service Defination

Entities registered in forFeature method will generate corresponding mapper objects witch type is mapping.ModelMapper and can be injected by @InjectMapper decorator.

import { Injectable } from "@nestjs/common";
import { Client } from "cassandra-driver";

import { InjectClient, InjectMapper, BaseService } from "cassandra-for-nest";
import Device from "device.entity";

@Injectable()
export default class DeviceService extends BaseService<Device> {
    constructor(
        @InjectMapper(Device) private readonly mapper, // inject mapper object
        @InjectClient() client: Client // inject cassandra connection client
    ) {
        super(client, mapper, Device); // inherit the parent class constructor
    }
}

As you can see, we can extend the BaseService class that implements the basic CRUD methods, includes:

• saveOne: Save a single entity.
• saveMany: Save multiple entities.
• finadAll: Query the full table, it is quivalent to the findAll method in the ModelMapper class in cassandra-driver, there is a limit on the number of results for a single query, default is 5000.
• findRealAll: Query the full table, unlike findAll, there is no limit on the number of results for a single query, because it will converted to eachRow method to perform query operations.
• findMany: Query based on conditions, it is quivalent to the find method in the ModelMapper class in cassandra-driver, there is a limit on the number of results for a single query, default is 5000.
• findRealMany: Query based on conditions, unlike findMany, there is no limit on the number of results for a single query, because it will converted to eachRow method to perform query operations.
• findOne: : Query based on conditions, return the first item that meets the condition.
• update: Update based on conditions, it is quivalent to the update method in the ModelMapper class in cassandra-driver.
• updateMany: Perform multiple conditional update operations.
• remove: Remove based on conditions, it is quivalent to the remove method in the ModelMapper class in cassandra-driver.
• removeMany: Perform multiple conditional remove operations.
• delete: delete use origin cql, can not write all primary keys

Usage In Controller

Inject service directly into the control layer:

// device.controller.ts
import DeviceService from "device.service"
export default class DeviceController {
    constructor(
        private readonly deviceService: DeviceService // inject
    ){}

    @Get('doSomthing')
    async doSomething() {
        // TODO
    }
}

Thanks

https://github.com/tensoar/cassandra-orm4nest