Fix N+1 query by using relation data

[Jade-GG]

ref: GT-2423

We ran into an issue with a massive N+1 query on the overview page of a runway resource. This was even more apparent when showing 500 results per page.

The reason for this is twofold:

• We don't eager load the entry data for everything, so when the retrieved event is fired for each model individually we also end up loading the data for each model individually.
• The retrieved event is fired before any eager loading has been done.¹

To fix this, I've turned the entry attribute into a relation that gets eager loaded, and I've also deferred the actual retrieving of the data from this relation to the throwMissingAttributeExceptionIfApplicable function² so that we only start querying this data when the relation is loaded.

Note that the relation is a bit hacky because we need to get the related key from the data json. Laravel doesn't allow for raw statements to be used as foreign keys, so this uses a table joined onto itself to add the variable from the json column as a regular column, which we can then use as regular foreign key.

Footnotes

1. See also: github.com/Eloquent emits event retrieved prior to finishing the entire retrieval process of eager loaded relations laravel/framework#29658 ↩

2. Same function we use for custom attributes in Rapidez v5: https://github.com/rapidez/core/blob/master/src/Models/Traits/HasCustomAttributes.php#L202-L205 ↩

[royduin]

Please review @indykoning and @kevinmeijer97

[kevinmeijer97]

Are we sure this can go?

[Jade-GG]

I assume this was for making sure no database queries get done when doing commands in pipelines right? I don't see where this would be a problem in this case with it being a relation now.