MongoDB CRUD Operations

Mongoose provides a simple schema based solution to model your app-data. In this post, we will see how we can sue it to write basic CRUD operations in Nodejs.

Understanding Schema

First lets write a mongoose schema for a sample requirement. Example entity is Team, where I want to save:

  • Team name
  • Tem members and their roles
  • Who created this team
  • CreatedAt and UpdatedAt timestamps

JSON data

First lets take a look on how the JSON data will look like:

{
  name: "My Super Team",
  createdBy: "[email protected]",
  members: [
    {
      email: "[email protected]",
      role: "admin"
    },
    {
      email: "[email protected]",
      role: "user"
    },
    {
      email: "[email protected]",
      role: "admin"
    }
  ]
}

Lets write it in mongoose schema language.

'use strict';

const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const timestamps = require('mongoose-timestamp');

const TeamMemberSchema = new Schema({
    email: String,
    role: String
});
TeamMemberSchema.plugin(timestamps);

const TeamSchema = new Schema({
    name: String,
    createdBy: String,
    members: [TeamMemberSchema]
}, {
    w: 'majority',
    wtimeout: 10000,
    collation: { locale: 'en', strength: 1 }
});

TeamSchema.plugin(timestamps);

module.exports = mongoose.model('Team', TeamSchema);

The model above is self explanatory. I have used a timestamp plugin for mongoose, which will automatically put two fields:

  • createdAt
  • updatedAt

Also, I have used a nested schema in above example. There is another important thing to see is that I have not defined _id field. Mongoose will automatically create this, if I have not mentioned it in my schema. I can also define how I would want my _id field to be generated.

Add New Record

add(args) {
    if (!args.name || !args.email) {
        return Promise.reject(new Error('Paass team name and creator email'));
    }
    //using winston logging
    logger.log('info', 'Adding team', {name: args.name, createdBy: args.email});

    let obj = new Team();
    obj.name = args.name;
    obj.createdBy = args.email;
    obj.members = [{
        email: args.email,
        role: args.role
    }];
    return obj.save();
}

Above code is pretty simple. You can add more robust checks, and error conditions. You might want to set data in cache.

Update Record

There are several ways you can update your record, it all depends on your need. Lets see few simple examples:

Simple update of a field

Say, we want to update team name.

By loading complete object

updateTeam(teamId, teamName) {
  return Team.findById(teamId)
    .then(team => {
      if (!team) {
        return Promise.reject(new Error('Team not found'));
      }
      team.name = teamName;
      return team.save();
    });
  return Team.upate({_id: args.teamId}, {
}

By NOT loading complete object

updateTeam(teamId, teamName) {
  return Team.upate({_id: args.teamId}, {
    name: teamName
  });
}

There are bunch of options to do update. You might want to see various options in mongoose documentation.

Get a Record

getById(teamId) {
  return Team.findById(teamId)
}

Delete Record

delete(teamId) {
  return Team.deleteOne({_id: teamId})
}

The examples above are simple and easy to understand. Let me know if if you have some comments.