How to get a Builder object from rows related to pivot - Laravel

问题

I'm trying to get all the "books" that one user have: but I can't do it how I need.

I use the following code:

/*Gets all books from the user whose id is 1*/     
$books= User::find(1)->books();

That return to me an Collection object; but I need a Builder object, as I get when I use the "select" method.

/* This code return me a "Builder" object */
Books::select(array('id', 'name', 'type'));

I need the Builder instead of Collection because I using Bllim/Datatables on my project and this package just accept a Builder object...

If I send it a Collection its throw me the next error (500 - Internal Server Error):

{
  "error":
   {
           "type":"ErrorException",
           "message":"Undefined property: Illuminate\\Database\\Eloquent\\Builder::$columns",
           "file":"\/var\/www\/proyect\/myproyect\/vendor\/bllim\/datatables\/src\/Bllim\/Datatables\/Datatables.php",
           "line":256
   }
}

Anybody knows the solution?

EDIT:

When I use the getQuery() method twice I get the following error:

{"error":{"type":"ErrorException","message":"array_values() expects parameter 1 to be array, null given","file":"\/var\/www\/proyect\/myproyect\/vendor\/bllim\/datatables\/src\/Bllim\/Datatables\/Datatables.php","line":550}}

Is rare, because when I used the "select" method Datatables worked perfectly...

This code works:

Books::select(array('id', 'name', 'type'));

But the code you told me doesn't work:

$user = User::find(1);
$user->books()->getQuery()->getQuery();

回答1:

Use method call books():

$user = User::find(1);

$user->books(); // relation object
$user->books; // dynamic property

First books() returns a relation object, that you can chain Eloquenr\Builder or Query Builder methods on.

Second books is a dynamic property - the query is automatically executed and its result is stored in the $user->relations['books'] and returned.

edit

As per comment - what you need is base Query\Builder object if you want to access columns property, so you need getQuery twice:

$user->books()
   ->getQuery() // get underlying Eloquent\Builder
   ->getQuery() // get underlying Query\Builder
   ->columns    // public property on the above

来源：https://stackoverflow.com/questions/27447389/how-to-get-a-builder-object-from-rows-related-to-pivot-laravel

标签

php

laravel-4

datatables

eloquent

one-to-many