How to dynamically connect to a MongoDB database using Nest.js

Question

I need to create a separate database for each entity in my client's app. I'm going to determine the database name according to the subdomain from which the request is coming from. How can I achieve that and connect dynamically to a database using nestjs and mongoose?

UserService

async findOneByEmail(email: string, subdomain: string): Promise<User | any> {
    const liveConnections = await Databases.getConnection(subdomain)

    const user = await liveConnections.model(User.name, UserSchema).find()
    // { 'securityInfo.email': email }
    if (!user)
        throw new HttpException(
            {
                status: HttpStatus.BAD_REQUEST,
                error: 'user not found',
                field: 'user',
            },
            HttpStatus.BAD_REQUEST
        )

    return user
}

class that I create

class DataBases extends Mongoose {
    private clientOption = {
        keepAlive: true,
        useNewUrlParser: true,
        useUnifiedTopology: true,
    }

    private databases: { [key: string]: Connection } = {}

    private getConnectionUri = (companyName = '') =>
        `mongodb+srv://${process.env.MONGODB_USERNAME}:${process.env.MONGODB_PASSWORD}@cluster0.2lukt.mongodb.net/${companyName}?retryWrites=true&w=majority`

    public async getConnection(companyName = ''): Promise<Connection> {
        const connection = this.databases[companyName]
        return connection ? connection : await this.createDataBase(companyName)
    }

    private async createDataBase(comapnyName = ''): Promise<Connection> {
        //  create new connection and if the database not exists just create new one
        const newConnection = await this.createConnection(
            this.getConnectionUri(comapnyName),
            this.clientOption
        )
        this.databases[comapnyName] = newConnection
        return newConnection
    }
}



 

Answer 1

I fix it. the DataBases Class that I create works really great and if you know a better way please tell me . what I had to change is the way I use the connection to MongoDB. and now I can connect to different databases depends on the subdomain.

I hope it will help someone!

UserService

async findOneByEmail(email: string, subdomain: string): Promise<User | any> {
    const liveConnections = await Databases.getConnection(subdomain)
    const user = await liveConnections
        .model(User.name, UserSchema)
        .findOne({ 'securityInfo.email': email })
        .exec()
    if (!user)
        throw new HttpException(
            {
                status: HttpStatus.BAD_REQUEST,
                error: 'user not found',
                field: 'user',
            },
            HttpStatus.BAD_REQUEST
        )

    return user
}