Laravel在播种表时设置增量id值

Question

I'm trying to seed a MySql table using Laravel seeder class. The problem is that it is not assigning the id field (which is an incremental) value as I set. In the seeder class I got:

public function run()
{

    Patropi\Entidade::create([
        'id' => '0',
        'nome' => 'entidade 0',
        'cpfcnpj' => '12345678901'
    ]);

    Patropi\Fornecedor::create([
        'id' => '0',
        'prioridade' => '0'
    ]);
}

On the database, the Fornecedor table id is a foreign key which references the Entidade id, that's why I want to have the same Id on both. The problem is, when it inserts on Entidade it doesn't put it as id = 0 but instead it gives the value of the last incremental + 1. How to force laravel to insert 0 there instead? Thanks in advance.

Answer 1

Storing NULL or 0 in the auto-incrementing field is one of the triggers to assign the next incremental value.

From the MySQL docs:

You can also explicitly assign 0 to the column to generate sequence numbers.

If you want to disable this functionality, you can turn on the NO_AUTO_VALUE_ON_ZERO sql mode. This will change MySQL so that only assigning NULL will assign the next incremental value, and will allow you to store 0 in the field. From the docs:

NO_AUTO_VALUE_ON_ZERO affects handling of AUTO_INCREMENT columns. Normally, you generate the next sequence number for the column by inserting either NULL or 0 into it. NO_AUTO_VALUE_ON_ZERO suppresses this behavior for 0 so that only NULL generates the next sequence number.

This mode can be useful if 0 has been stored in a table's AUTO_INCREMENT column. (Storing 0 is not a recommended practice, by the way.)

If you don't explicitly need the id to be 0, then I would not try to assign 0. If the id doesn't matter, then you can do this:

public function run()
{
    $entidade = Patropi\Entidade::create([
        'nome' => 'entidade 0',
        'cpfcnpj' => '12345678901'
    ]);

    Patropi\Fornecedor::create([
        'id' => $entidade->id,
        'prioridade' => '0'
    ]);
}

Or, if you have the Eloquent relationships setup:

public function run()
{
    $entidade = Patropi\Entidade::create([
        'nome' => 'entidade 0',
        'cpfcnpj' => '12345678901'
    ]);

    // assumes fornecedor() defines a hasone/hasmany relationship.
    $entidade->fornecedor()->create([
        'prioridade' => '0'
    ]);
}