Remove a foreign key constraint in a Laravel migration

Dropping a foreign key constraint might sound like an odd thing to do. But in some cases you need to. For example, when you turn a foreign key field into a polymorphic relationship.

In such a case you want to use the dropForeign() method, which takes the name of the foreign key constraint in your database. This name takes the following form: {table}_{column}_foreign.

Thus, if you would have a foreign key constraint in the tasks table for the user_id column, you could drop the key constraint using the following migration.

<?php

public function up()
{
    Schema::table('tasks', function (Blueprint $table) {
        $table->dropForeign('tasks_user_id_foreign');
    });
}