Laravel migration to add nullable attribute to existing table column

Question

I have started writing a small personal project on Laravel 10. The problem I encountered is as follows:

1. I have a user table with a foreign key UUID - role_id.
2. I want to add nullable attribute on this column without deleting the table.
3. I created a new migration to make the changes.
4. The doctrine/dbal package is installed in order to (theoretically) change columns.
5. My code in the migration is as follows:

public function up(): void
    {
        Schema::table('users', function (Blueprint $table) {
            $table->foreignUuid('role_id')->nullable()->constrained('roles')->change();
        });
    }

    /*** Reverse the migrations.*/
    public function down(): void
    {
        Schema::table('users', function (Blueprint $table) {
            $table->foreignUuid('role_id')->nullable(false)->constrained('roles')->change();
        });
    }

But when I run php artisan migrate, I get the following error - SQLSTATE[42S21]: Column already exists: 1060 Duplicate column name 'role_id' (Connection: mysql, SQL: alter table users add role_id char(36 ) null).

Any suggestions on how to modify the columns correctly would be greatly appreciated.

Answer 1

You can try the following:

      Schema::table('users', function (Blueprint $table) {
            $table->char('role_id', 36)->nullable()->constrained('roles')->change();
        });

Or you can use the original SQL statement:

    DB::statement('ALTER TABLE users MODIFY role_id CHAR(36) NULL');
    DB::statement('ALTER TABLE users ADD CONSTRAINT fk_users_role_id FOREIGN KEY (role_id) REFERENCES roles (id)');