How to Create a New Migration in Laravel (Practical Examples)

Laravel, a robust PHP framework, is renowned for its elegant syntax and tools that make web development a breeze. Among its many features, database migrations stand out, offering a version control system for your database schema. This article provides a comprehensive, step-by-step guide to creating and implementing a new migration in Laravel, accompanied by a practical example.

What is a Migration?

A migration in Laravel is akin to a blueprint for your database. It allows you to define the structure of your database tables and their relationships. Migrations are PHP files that contain a class with methods to run (up) and rollback (down) the changes.

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Prerequisites

• Basic knowledge of PHP and Laravel.
• Laravel environment set up (Laravel version 8.x or later recommended).
• Database connection configured in .env file.

Step 1: Creating a New Migration

To create a new migration, use the Artisan CLI provided by Laravel. Open your terminal and navigate to your Laravel project directory. Run the following command:

php artisan make:migration create_users_table 

This command creates a new migration file for a users table in the database/migrations directory.

Step 2: Defining the Migration

Open the newly created migration file. You will see two methods: up() and down(). In the up() method, define the table’s columns and constraints. For example:

public function up()
{
    Schema::create('users', function (Blueprint $table) {
        $table->id();
        $table->string('name');
        $table->string('email')->unique();
        $table->timestamp('email_verified_at')->nullable();
        $table->string('password');
        $table->rememberToken();
        $table->timestamps();
    });
}

The down method is used to rollback the migration. Usually, it reverses the operations performed in the up method:

public function down()
{
    Schema::dropIfExists('users');
}

Step 3: Running the Migration

To execute the migration, run the following command:

php artisan migrate 

This command runs all outstanding migrations, creating the users table in your database.

Step 4: Rolling Back a Migration

If you need to undo a migration, Laravel provides a rollback feature. Execute:

php artisan migrate:rollback 

This command will call the down method of the latest batch of migrations.

Let’s Do Some Practical Examples

Example 1: Adding a New Column

1. Suppose you want to add a new column, phone_number, to the users table. First, create a new migration:

   php artisan make:migration add_phone_number_to_users_table 
   

2. In the migration file, write:

   
   public function up()
   {
       Schema::table('users', function (Blueprint $table) {
           $table->string('phone_number')->nullable();
       });
   }
   
   public function down()
   {
       Schema::table('users', function (Blueprint $table) {
           $table->dropColumn('phone_number');
       });
   }
   
   

3. Run php artisan migrate to apply the changes.

   php artisan migrate 
   

Example 2: Altering an Existing Column

Sometimes, you might need to modify the attributes of an existing column in your database. This is often necessary when business requirements change, or you need to refine your database schema. Let’s consider an example where we need to alter an existing column in the users table.

Scenario: Suppose we have an existing email column in our users table, and we want to change its character limit from the default value to 150 characters.

1. Creating a New Migration: As with any database schema change, we start by creating a new migration:

   php artisan make:migration update_email_length_in_users_table 
   

   This command will create a new migration file in the database/migrations directory.

2. Writing the Migration to Alter the Column: Open the newly created migration file and use the Schema facade to alter the email column. Your migration might look something like this:

   
   public function up()
   {
       Schema::table('users', function (Blueprint $table) {
           $table->string('email', 150)->change();
       });
   }
   
   public function down()
   {
       Schema::table('users', function (Blueprint $table) {
           $table->string('email', 255)->change();
       });
   }
   
   

   In the up method, we change the email column to have a maximum length of 150 characters. The down method is used to revert this change, setting the length back to the default 255 characters.

   Note: To use the change() method, you need to ensure that the `doctrine/dbal` package is installed in your Laravel project as it’s required for altering columns.

3. Running the Migration: To apply the changes, run the migration:

   php artisan migrate 
   

   This will alter the email column in your users table to have a maximum length of 150 characters.

4. Verifying the Changes: After running the migration, it’s good practice to verify that the changes have been applied correctly. You can do this by inspecting the structure of the users table in your database management tool or querying the schema information using Laravel’s database tools.

Conclusion
Migrations in Laravel offer an efficient way to manage your database schema changes. By following these steps, you can easily add, modify, or rollback database tables and columns, ensuring smooth and consistent development across different environments. Remember, migrations are a powerful tool in Laravel’s arsenal, enabling developers to build and maintain databases with ease.