Error when migrating with Laravel in Heroku to Postgres - laravel

Question

I'm working with Laravel 5.6 and Heroku with Postgres database.
I have uploaded my application to Heroku, the login form shows it to me correctly.
The problem comes when doing the migration of the tables with:
heroku run php artisan migrate and using Postgres of Heroku, I made all the configuration correctly but when doing migrate this happens:
In Connection.php line 664:
SQLSTATE[42830]: Invalid foreign key: 7 ERROR: there is no unique
constraint matching given keys for referenced ta ble "users" (SQL:
alter table "sales" add constraint "sales_user_id_foreign" foreign key
("user_id") references "us ers" ("id"))
In Connection.php line 458:
SQLSTATE[42830]: Invalid foreign key: 7 ERROR: there is no unique
constraint matching given keys for referenced ta ble "users"
The strange thing is that the same migration locally does not cause me any problems (MySQL) but Heroku with Postgres show the error.
These are my User and Sales migrations:
Users:
public function up()
{
Schema::create('users', function (Blueprint $table) {
$table->integer('id')->unsigned();
$table->foreign('id')->references('id')->on('people')->onDelete('cascade');
$table->string('user')->unique();
$table->string('password');
$table->boolean('state')->default(1);
$table->integer('idRole')->unsigned();
$table->foreign('idRole')->references('id')->on('roles');
$table->rememberToken();
//$table->timestamps();
});
}
Sales:
public function up()
{
Schema::create('sales', function (Blueprint $table) {
$table->increments('id');
$table->integer('client_id')->unsigned();
$table->foreign('client_id')->references('id')->on('people');
$table->unsignedInteger('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users');
$table->dateTime('date_time');
$table->decimal('total', 11, 2);
$table->string('status', 20);
$table->timestamps();
});
}
I do not know why I have this error in Heroku but everything works locally. How can I fix this?

Answer 1

It's because the id column on the table users does not have the unique constraint.
You can set the id column as auto-increment and run the migration again:
Users
public function up()
{
Schema::create('users', function (Blueprint $table) {
$table->increments('id');
// Other codes
});
}

Answer 2

The strange thing is that the same migration locally does not cause me any problems (MySQL) but Heroku with Postgres show the error.
It's always a good idea to use the same database software in development and production. MySQL and PostgreSQL aren't drop-in replacements for each other, even with an ORM and a schema migration tool. There are definitely situations where one will be happy and the other won't.
I suspect that if you use MySQL on Heroku your issue will disappear. Heroku doesn't provide MySQL itself, but there are a couple of addons that you could use. JawsDB and ClearDB are both popular options, or if you prefer you could host your own MySQL database on something like RDS.
You could also switch to Postgres locally and see if you can reproduce the error.