Why ->latest method in model method read all rows from related table?-CodePudding

In laravel 9 I got last value in related CurrencyHistory table

$currencies = Currency
    ::getByActive(true)
    ->withCount('currencyHistories')
    ->with('latestCurrencyHistory')
    ->orderBy('ordering', 'asc')
    ->get();

In model app/Models/Currency.php I have :

public function latestCurrencyHistory()
{
    return $this->hasOne('App\Models\CurrencyHistory')->latest();
}

But checking generated sql I see lines like :

   SELECT * 
    FROM `currency_histories` 
    WHERE `currency_histories`.`currency_id` in (8, 13, 16, 19, 27, 30) 
    ORDER BY `created_at` desc

I suppose this code is raised by latestCurrencyHistory method and wonder can I set some limit 1 condition here, as resulting data are too big.

Thanks!

CodePudding user response：

Query is correct. As you eager load your relation for the collection of currencies using with method, you load currency_histories for all of your Currency models in collection.

If you dump the result, you will have currencies with IDs: 8, 13, 16, 19, 27, 30 and one latestCurrencyHistory (if present) for each.