Laravel 5.x - Eloquent模型如何成为QueryBuilder？

Question

I am trying to understand how could an Eloquent model also be a query builder. I could not see any polymorphic relationship between Illuminate\Database\Eloquent\Model class and Illuminate\Database\Query\Builder class in the source code. There is no inheritance or interface implementation between these two classes.

So, could anyone please explain how Laravel made it possible for an eloquent model to be a query builder? Thanks in advance.

Edit: I am asking this question because I don't understand how I could call the methods in Builder class through my models, e.g. ModelObject::orderBy('created_at', 'asc')->get(), where orderBy() is a method in Builder class.

Answer 1

There is a query() function on the Eloquent base model which creates a new query builder instance when being called (with the table of the model being already set for the builder). You can find the function here.

Additionally to that, the magic __call() and __callStatic() functions create a new query builder and delegate the method call to this builder whenever a function is called that is not part of the Eloquent model and which they don't have an implicit call for (like increment(), decrement()). You can find the code for this here.

So to sum it up: it's magic. The magic functions.