MongoDB Tutorial

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MongoDB Schema Validation

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MongoDB Schema Validation

Introduction

Learn how to enforce data integrity and structure in MongoDB using schema validation rules.

Connecting to MongoDB

Before applying schema validation rules, ensure you are connected to your MongoDB server:

Example: Connecting to MongoDB

mongosh

This command starts the mongosh shell and connects to the default MongoDB server running locally.

Switching to a Database

Switch to the database where your collection resides using the use command:

Example: Switching to a Database

use mydatabase

This command switches to the “mydatabase” database. Replace mydatabase with your database name.

Enabling Schema Validation

Enable schema validation for a collection using the collMod command:

Example: Enabling Schema Validation

db.createCollection("mycollection", {
    validator: {
        $jsonSchema: {
            bsonType: "object",
            required: ["name", "age"],
            properties: {
                name: {
                    bsonType: "string",
                    description: "must be a string and is required"
                },
                age: {
                    bsonType: "int",
                    description: "must be an integer and is required"
                }
            }
        }
    }
})

This command creates a collection mycollection with schema validation rules. Documents must have name (string) and age (integer) fields.

Validation Rules

Define validation rules using JSON schema:

bsonType: Specifies the BSON type of the field.
required: Specifies required fields.
properties: Defines field properties and types.
description: Provides a description of the field.

Validation Errors

Handle validation errors when documents do not meet schema rules:

Example: Handling Validation Errors

db.mycollection.insertOne({ name: "John" })

If the document doesn’t include the age field, MongoDB will throw a validation error.

Updating Validation Rules

Update validation rules using the collMod command:

Example: Updating Validation Rules

db.runCommand({
    collMod: "mycollection",
    validator: {
        $jsonSchema: {
            bsonType: "object",
            required: ["name", "age", "email"],
            properties: {
                name: {
                    bsonType: "string",
                    description: "must be a string and is required"
                },
                age: {
                    bsonType: "int",
                    description: "must be an integer and is required"
                },
                email: {
                    bsonType: "string",
                    pattern: "^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$",
                    description: "must be a valid email address"
                }
            }
        }
    }
})

This command updates the schema validation rules to include the email field with a regex pattern for email validation.

Conclusion

Schema validation in MongoDB ensures data integrity by enforcing structure and type constraints on documents. Define and update validation rules to meet your application’s requirements and maintain consistent data quality.

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