Cannot add foreign key constraint [Laravel 5.6] - mysql

Question

tl;dr. Solution:
Thanks to Jonas.
the problem was that the tables I was referring as foreign, were not InnoDB.
I added raw SQL statements in alter migrations and then added the foreign keys:
DB::statement("ALTER TABLE table ENGINE='InnoDB';");
Original question
First, before the Stackoverflow police bust me, I know this question is probably 83% of the database of this website. But me is special (Kidding, I know I'm not). But I've tried most of the common stuff and nothing seems to work. So probably I'm overseeing something.
Error
General error: 1215 Cannot add foreign key constraint (SQL: alter table applications add constraint applications_user_id_foreign foreign key (user_id) references users (id) on delete cascade)
This is my migration:
public function up()
{
Schema::create("applications", function(Blueprint $table) {
$table->engine = "InnoDB";
$table->increments('id');
$table->timestamps();
});
Schema::table('applications', function($table) {
$table->integer('user_id')->unsigned()->index();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
$table->integer('job_request_id')->unsigned()->index();
$table->foreign('job_request_id')->references('id')->on('job_requests')->onDelete('cascade');
$table->integer('status')->default(0);
});
}
What I've already tried:
1.
public function up()
{
Schema::create("applications", function(Blueprint $table) {
$table->increments('id');
$table->timestamps();
$table->integer('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
$table->integer('job_request_id')->unsigned();
$table->foreign('job_request_id')->references('id')->on('job_requests')->onDelete('cascade');
$table->integer('status')->default(0);
});
}
2.
public function up()
{
Schema::create("applications", function(Blueprint $table) {
$table->engine = "InnoDB";
$table->increments('id');
$table->timestamps();
$table->integer('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
$table->integer('job_request_id')->unsigned();
$table->foreign('job_request_id')->references('id')->on('job_requests')->onDelete('cascade');
$table->integer('status')->default(0);
});
}
Splitting the migration into two files (A create and an alter). Even adding each reference one by one.
4.- using DB::statement('SET FOREIGN_KEY_CHECKS=0;'); and =1 at the beginning an the end og the migration.
5.- removing the unsigned() and the index().
Might mean something:
1.- When I rollback the migration, it doesn't delete the table. So if I rollback and migrate, would give me a "already exists error".
2.- I already have migrations which reference the same items, i.e:
Schema::create('job_requests', function (Blueprint $table) {
...
$table->integer('user_id')->unsigned()->nullable();
$table->foreign('user_id')->references('id')->on('users');
...
});
UPDATE
For the drop methods I've tried:
For the create migrations
public function down()
{
Schema::drop('applications');
}
public function down()
{
Schema::dropIfExists('applications');
}
2.- For the alter migrations
public function down()
{
Schema::table('applications', function (Blueprint $table) {
$table->dropForeign(['user_id']);
$table->dropColumn('user_id');
$table->dropForeign(['job_request_id']);
$table->dropColumn('job_request_id');
});
}
UPDATE 2:
public function up()
{
Schema::create('users', function (Blueprint $table) {
$table->increments('id');
$table->string('first_name');
$table->string('last_name')->nullable();
$table->string('password');
$table->rememberToken();
$table->timestamps();
});
}
/**
* Reverse the migrations.
*
* #return void
*/
public function down()
{
Schema::dropIfExists('users');
}
public function up()
{
Schema::create('job_requests', function (Blueprint $table) {
$table->increments('id');
$table->integer('status')->default(0);
$table->integer('user_id')->unsigned()->nullable();
$table->foreign('user_id')->references('id')->on('users');
$table->timestamps();
});
}
/**
* Reverse the migrations.
*
* #return void
*/
public function down()
{
Schema::dropIfExists('job_requests');
}
I added three more alter migration:
public function up()
{
Schema::table('users', function (Blueprint $table) {
$table->engine = "InnoDB";
});
}
///////////////////////////
public function up()
{
Schema::table('job_requests', function (Blueprint $table) {
$table->engine = "InnoDB";
});
}
///////////////////////////
public function up()
{
Schema::table('applications', function (Blueprint $table) {
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
$table->foreign('job_request_id')->references('id')->on('job_requests')->onDelete('cascade');
});
}
/**
* Reverse the migrations.
*
* #return void
*/
public function down()
{
Schema::table('applications', function (Blueprint $table) {
$table->dropForeign(['user_id']);
$table->dropForeign(['job_request_id']);
});
}
Without luck yet.

Answer 1

The referenced tables also have to use the InnoDB engine.
You can change them with raw SQL statements:
DB::statement("ALTER TABLE users ENGINE='InnoDB';");
DB::statement("ALTER TABLE job_requests ENGINE='InnoDB';");

Answer 2

for deleting the table:
public function down()
{
Schema::disableForeignKeyConstraints();
Schema::dropIfExists('applications');
}