Laravel migration: “Foreign key constraint is incorrectly formed” (errno 150)

Question

When migrating my DB, this error appears. Below is my code followed by the error that I am getting when trying to run the migration.

Code

Answer 1

Laravel 5.8

In the foreign key column use unsignedBigInteger to avoid mismatch foreign key data type problem . For example let us assume we have two tables questions and replies
Questions table will look:

 public function up()
    {
        Schema::create('questions', function (Blueprint $table) {
            $table->bigIncrements('id');
             $table->text('body');
             $table->integer('user_id')->unsigned();
            $table->timestamps();
        });
    }

Replies table look like :

public function up()
{
    Schema::create('replies', function (Blueprint $table) {
        $table->bigIncrements('id');
        $table->text('body');
        $table->unsignedBigInteger('question_id');
        $table->integer('user_id')->unsigned();
        $table->foreign('question_id')->references('id')->on('questions')->onDelete('cascade');
        $table->timestamps();
    });
}