How to create an id using mongoose in Javascript?

Mongoose is a powerful tool that simplifies MongoDB operations by providing a structured way to define schemas and models. With Mongoose, developers can define relationships between data, apply validation rules, and create reusable query logic.

In this article, We will learn about Mongoose, Defining a Mongoose Schema and Default ID Generation in Mongoose, Custom ID Field in Mongoose Generating Custom IDs with Hooks and Using Plugins for ID Generation in detail.

Understanding Mongoose

• Mongoose simplifies database operations by providing a structured way to define schemas and models.
  
• It integrates easily with MongoDB, allowing developers to work with MongoDB documents in a more organized and efficient manner.
  
• With Mongoose, developers can define relationships between data, apply validation rules, and create reusable query logic.
  
• Mongoose provides a range of features, such as middleware hooks and to handle complex operations like data validation and transformation.
  
• Overall, Mongoose enhances the development experience when working with MongoDB in Node.js applications.

Defining a Mongoose Schema

Before creating IDs, we need to define a Mongoose schema. A schema represents the structure of documents within a collection.

Here's an example of defining a simple schema.

// Import the mongoose library
const mongoose = require('mongoose');

// Define a new mongoose schema for the user
const userSchema = new mongoose.Schema({
  name: String, // Define a field for the user's name of type String
  email: String // Define a field for the user's email of type String
});

// Create a new mongoose model based on the schema
const User = mongoose.model('User', userSchema); // 'User' is the model name, and userSchema is the schema

Default ID Generation in Mongoose

• Each document in a MongoDB collection requires a unique identifier, which MongoDB uses as the primary key.
  
• MongoDB uses ObjectId as the default unique identifier, which is a 12-byte value represented as a 24-character hexadecimal string.
  
• ObjectId includes a timestamp, machine identifier, process identifier, and a random value.
  
• When we define a Mongoose schema without specifying an ID field, Mongoose automatically adds an _id field with a generated ObjectId value to our documents.

// Import the mongoose library
const mongoose = require('mongoose');

// Define a new mongoose schema for the model
const schema = new mongoose.Schema({
  name: String, // Define a field for the name of type String
  age: Number // Define a field for the age of type Number
});

// Create a new mongoose model based on the schema
const Model = mongoose.model('Model', schema); // 'Model' is the model name, and schema is the schema

// Create a new instance of the Model with name 'John' and age 30
const instance = new Model({ name: 'John', age: 30 });

// Log the newly created instance
console.log(instance); // { _id: 5c4830d4b55ae6b12b8b518c, name: 'John', age: 30 }

Custom ID Field in Mongoose

• ObjectId is suitable for most scenarios, but there are cases where custom IDs are preferred, such as using sequential numbers or UUIDs for readability or integration with external systems.
  
• To define a custom ID field in Mongoose, we can explicitly specify the _id field in our schema.

// Define a new mongoose schema for the custom model
const customSchema = new mongoose.Schema({
  customId: String, // Define a field for the customId of type String
  name: String, // Define a field for the name of type String
  age: Number // Define a field for the age of type Number
});

// Create a new mongoose model based on the custom schema
const CustomModel = mongoose.model('CustomModel', customSchema); // 'CustomModel' is the model name, and customSchema is the schema

// Create a new instance of the CustomModel with customId '123abc', name 'Alice', and age 25
const customInstance = new CustomModel({ customId: '123abc', name: 'Alice', age: 25 });

// Log the newly created customInstance
console.log(customInstance); // { _id: '123abc', name: 'Alice', age: 25 }

Generating Custom IDs with Hooks

• Mongoose provides pre and post hooks that enable us to execute functions before or after operations like saving or updating documents.
  
• Hooks can be helpful to dynamically generate custom IDs before saving documents to the database.

// Define a pre-save hook on the customSchema to generate a customId if not already set
customSchema.pre('save', function(next) {
  if (!this.customId) {
    // Call the generateCustomId function to generate a custom ID
    this.customId = generateCustomId();
  }
  next();
});

// Function to generate a custom ID
function generateCustomId() {
  // Placeholder logic to generate a custom ID
  return 'generatedID123'; // Return a hardcoded custom ID for demonstration purposes
}

By attaching a pre('save') hook to your schema, you ensure that the custom ID is generated before saving the document.

Using Plugins for ID Generation

Mongoose allows us to create and reuse plugins to extend schema functionality. We can encapsulate ID generation logic within a plugin and apply it to multiple schemas across our application.

// Define a plugin called idGeneratorPlugin to add customId field and pre-save hook to the schema
const idGeneratorPlugin = function(schema, options) {
  // Add a customId field to the schema
  schema.add({ customId: String });

  // Define a pre-save hook to generate a customId if not already set
  schema.pre('save', function(next) {
    if (!this.customId) {
      // Call the generateCustomId function to generate a custom ID
      this.customId = generateCustomId();
    }
    next();
  });

  // Function to generate a custom ID
  function generateCustomId() {
    // Placeholder logic to generate a custom ID
    return 'generatedID123'; // Return a hardcoded custom ID for demonstration purposes
  }
};

// Apply the idGeneratorPlugin to the customSchema
customSchema.plugin(idGeneratorPlugin);

By applying the idGeneratorPlugin to our schema, we can easily generate custom IDs for multiple models with minimal code duplication.

Conclusion

In this guide, we've learn about various methods for generating custom IDs using Mongoose in JavaScript. From utilizing default ObjectId to defining custom ID fields and implementing ID generation logic with hooks and plugins, you have a range of options to suit your application's requirements.

By understanding these concepts and best practices, you can effectively manage unique identifiers in your MongoDB-powered applications, ensuring data integrity and consistency. Whether you're a beginner or an experienced developer, mastering ID generation with Mongoose is a valuable skill in modern web development.