How Do You Create a Collection in MongoDB and Specify the Data Type for the Fields?


Angela Bailey

Creating a Collection in MongoDB and Specifying Data Types for Fields

MongoDB is a popular NoSQL database that allows you to store and manage your data in a flexible and scalable manner. One of the key concepts in MongoDB is the collection, which is equivalent to a table in a relational database. In this tutorial, we will learn how to create a collection and specify the data types for its fields.

What is a Collection?
A collection in MongoDB is a group of documents that are stored together. It is schema-less, which means that each document can have its own structure and fields. This flexibility makes MongoDB a great choice for handling unstructured or semi-structured data.

Creating a Collection
To create a collection in MongoDB, we use the `db.createCollection()` method. Let’s say we want to create a collection called “users”. Here’s how we can do it:


This will create an empty collection named “users” in the current database.

Specifying Data Types for Fields
By default, MongoDB does not enforce any specific data types for fields within documents. However, you can specify the data type using JSON Schema validation.

JSON Schema Validation
JSON Schema is a powerful tool for validating and describing the structure of JSON documents. With JSON Schema validation, you can define rules for each field in your documents, including specifying data types.

To enable JSON Schema validation on a collection, you need to define a validator when creating the collection or modify an existing one.


Let’s say we want to create a collection called “products” with two fields: “name” of type string and “price” of type number.createCollection(“products”, {
validator: {
$jsonSchema: {
bsonType: “object”,
required: [“name”, “price”],
properties: {
name: {
bsonType: “string”
price: {
bsonType: “number”

In the above example, we specify that the “products” collection should have documents with a “name” field of type string and a “price” field of type number. The `required` property ensures that both fields are present in each document.

Now, if we try to insert a document into the “products” collection that doesn’t match the specified data types, MongoDB will throw an error.

In this tutorial, we learned how to create a collection in MongoDB and specify the data types for its fields using JSON Schema validation. By enforcing data types, we can ensure consistency and integrity in our data. MongoDB’s flexibility and scalability make it an excellent choice for managing structured, semi-structured, and unstructured data.

Now that you have a basic understanding of creating collections and specifying data types in MongoDB, you can explore more advanced features like indexing, querying, and aggregation to unleash the full power of this NoSQL database. Happy coding!

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