withCount bug when using custom select

[mnabialek]

• Laravel Version: v5.6.26
• PHP Version: 7.2.5
• Database Driver & Version: MySQL 8.0.11

Description:

Using withCount together with conditions and custom select causes running invalid queries.

Steps To Reproduce:

When having relationship defined like this:

public function userImages()
{
    return $this->hasMany(Image::class)->where('type', 'user');
}

When running code like this:

$query = Model::where('status', 'online')->select(['*'])->withCount('userImages');

or

$query = Model::where('status', 'online')->withCount('userImages');

SQL looks like this:

select `models`.*, (select count(*) from `images` where `models`.`id` = `images`.`model_id` and `type` = ?) as `user_images_count` from `models` where `status` = ?

and bindings look like this:

array:2 [
  0 => "user"
  1 => "online"
]

so everything is as expected.

But running code like this

$query = Model::where('status', 'online')->withCount('userImages')->select(['*']);

SQL looks like this:

select * from `models` where `status` = ?

and bindings looks like this:

array:2 [
  0 => "user"
  1 => "online"
]

The are at least 3 problems here:

1. $result->user_images_count will result invalid value
2. bindings are wrong so invalid data will be taken from database
3. there is no exception thrown anywhere (or any information about such behavior in documentation) so without debugging query it's really hard to detect that query is completely invalid

[Harry-Torry]

With how select() sets the columns ($this->columns = is_array($columns) ? $columns : func_get_args();), it wipes the columns that get set by the withCount() call. You're explicitly stating you want XYZ field and then removing that field.

Try calling the select() before the withCount()!

[Harry-Torry]

Here's another one about the same "issue" - #19388.

[mnabialek]

@Harry-Torry I'm total aware that changing order fix the issue (I showed this in the issue). I also saw implementation, but it's quite risky when it works like this and there is no additional information about this in documentation.

[Harry-Torry]

Submit a PR to the docs 👍