Laravel如何在构建查询时访问关系？

Question

Let's say I have tables

companies id | name
guests id | name
books id | name

They have models with relations
Company -> hasMany -> Guest
Guest -> hasMany -> Book

Now, I wanna get all books where guests from particular company
I have no Idea how to reach that in eloquent ORM
I will apreciate any help
Thanks

Answer 1

You can use whereHas to query based on the existence of relationships:

$books = Book::whereHas('guest.company', function ($query) use ($companyId) {
    $query->where('id', $companyId);
})->get();

Roughly: get all books that belong to a guest that belongs to a company with id of $companyId

Laravel Docs - 5.6 - Eloquent - Relationships - Querying Relationship Existence