[6.0] Add a searchableWith property to eager load some relations on batch indexing (scout:import)

[tarekbazine]

referring to this issues.

todo :

• tests
• update laravel scout docs (adding this property)

i really want to help for the tests but i did not know where to start, feedbacks will be appreciated.

[nunomaduro]

Thanks for this proposal. I like the idea, but your implementation contains some issues.

Loading a relation using the with on the makeAllSearchable method changes the default result of the toSearchableArray method. As example, the result of the scout:import would be a record with:

array:10 [
  "id" => 57
  "user_id" => 40
  "image_url" => "https://lorempixel.com/640/480/?35139"
  "title" => "Configure models"
  "user" => array:6 [ // <--- here...
    "id" => 40
    "name" => "Rhett Kozey"
    "email" => "qhegmann@example.net"
    "email_verified_at" => "2019-01-07 17:21:14"
    "created_at" => "2019-01-07 17:21:15"
    "updated_at" => "2019-01-07 17:21:15"
  ]
]

Horever, the result of toSearchableArray using the normal auto indexing would be the same record without the user key:

array:10 [
  "id" => 57
  "user_id" => 40
  "image_url" => "https://lorempixel.com/640/480/?35139"
  "title" => "Configure models"
]

[nunomaduro]

But let's wait until @taylorotwell or @driesvints jump on this.

[driesvints]

Hmm, think it's best that we hold off on this implementation. @nunomaduro can you jump in on the issue to figure out a solution first before we accept a PR? Thanks!

[fitztrev]

@nunomaduro @driesvints - I don't understand the problem with this PR. What you describe is the behavior I would expect to happen.

class Post extends Model
{
    protected $with = ['user'];
}

class Post extends Model
{
    protected $searchableWith = ['user'];
}

The property $searchableWith behaves the same as $with, but allows you to load those relationships only in the context of indexing records. So if your toSearchableArray contains data from a relationship, you can eager load and make the scout:import command much faster and more efficient.

This PR fixes #329 and algolia/scout-extended#90 for me.

[ultrono]

@fitztrev I think @nunomaduro takes issue with the fact that unless the toSearchableArrray() method is defined on the model, the relationship is also indexed.

Using the code from this PR, to index 16,500 records, with a single relationship (a booking model, with a 'customer' relationship) massively speeds up indexing.

With eager loading the process takes 4 mins 24 seconds. WIthout eager loading the time increases 11 mins 09 seconds.

I'm using the TNTSearch driver.

EDIT 07/03/20:

I've just come across matchish/laravel-scout-elasticsearch#31 (comment), which suggests creating a separate model, with global scope applied (although I assume I could just populate "with" property on the model. I tend index records on my new model. This is farr from ideal, but without support to eager loads relationships there isn;t particularly any option I'm aware of.