email as a foreign key in larave - laravel

Question

Can I make email as a foreign key ? $table->foreignId('email')->constrained('users')->onDelete('CASCADE'); . I wrote a seeder and is for an integer value for emai. I need to make email unique
This is my users table
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();
});

Answer 1

To create an Foreign Key association with email column of users table, you cannot use foreignId method as it creates unsignedBigInteger equivalent column.
You can create the foreign key association as
//Some other table - for eg lets say posts
Schema::create('posts', function(Blueprint $table) {
$table->id();
$table->string('title');
$table->text('body');
$table->string('author_email');
$table->foreign('author_email') // a column on posts table
->references('email') //name of the column on users (referenced) table
->on('users') //name of the referenced table
->onDelete('cascade'); //constrain
});
Then using this foreign key association you can define the author relation in Post model linking it to the User model
//Post.php - eloquent model class
public function author()
{
return $this->belongsTo(User::class, 'author_email', 'email');
}
Note: For this to work as expected, email column on users table must contain unique values i.e have a unique index (as you have in the migration of users table)
Laravel Docs - Migrations - Foreign Key Constraints