Updating timestamps on attaching/detaching Eloquent relations - php

Question

I'm using Laravel 4, and have 2 models:
class Asset extends \Eloquent {
public function products() {
return $this->belongsToMany('Product');
}
}
class Product extends \Eloquent {
public function assets() {
return $this->belongsToMany('Asset');
}
}
Product has the standard timestamps on it (created_at, updated_at) and I'd like to update the updated_at field of the Product when I attach/detach an Asset.
I tried this on the Asset model:
class Asset extends \Eloquent {
public function products() {
return $this->belongsToMany('Product')->withTimestamps();
}
}
...but that did nothing at all (apparently). Edit: apparently this is for updating timestamps on the pivot table, not for updating them on the relation's own table (ie. updates assets_products.updated_at, not products.updated_at).
I then tried this on the Asset model:
class Asset extends \Eloquent {
protected $touches = [ 'products' ];
public function products() {
return $this->belongsToMany('Product');
}
}
...which works, but then breaks my seed which calls Asset::create([ ... ]); because apparently Laravel tries to call ->touchOwners() on the relation without checking if it's null:
PHP Fatal error: Call to undefined method Illuminate\Database\Eloquent\Collection::touchOwners() in /projectdir/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php on line 1583
The code I'm using to add/remove Assets is this:
Product::find( $validId )->assets()->attach( $anotherValidId );
Product::find( $validId )->assets()->detach( $anotherValidId );
Where am I going wrong?

Answer 1

You can do it manually using touch method:
$product = Product::find($validId);
$product->assets()->attach($anotherValidId);
$product->touch();
But if you don't want to do it manually each time you can simplify this creating method in your Product model this way:
public function attachAsset($id)
{
$this->assets()->attach($id);
$this->touch();
}
And now you can use it this way:
Product::find($validId)->attachAsset($anotherValidId);
The same you can of course do for detach action.
And I noticed you have one relation belongsToMany and the other hasMany - it should be rather belongsToMany in both because it's many to many relationship
EDIT
If you would like to use it in many models, you could create trait or create another base class that extends Eloquent with the following method:
public function attach($id, $relationship = null)
{
$relationship = $relationship ?: $this->relationship;
$this->{$relationship}()->attach($id);
$this->touch();
}
Now, if you need this functionality you just need to extend from another base class (or use trait), and now you can add to your Product class one extra property:
private $relationship = 'assets';
Now you could use:
Product::find($validId)->attach($anotherValidId);
or
Product::find($validId)->attach($anotherValidId, 'assets');
if you need to attach data with updating updated_at field. The same of course you need to repeat for detaching.

Answer 2

From the code source, you need to set $touch to false when creating a new instance of the related model:
Asset::create(array(),array(),false);
or use:
$asset = new Asset;
// ...
$asset->setTouchedRelations([]);
$asset->save();

Answer 3

Solution:
Create a BaseModel that extends Eloquent, making a simple adjustment to the create method:
BaseModel.php:
class BaseModel extends Eloquent {
/**
* Save a new model and return the instance, passing along the
* $options array to specify the behavior of 'timestamps' and 'touch'
*
* #param array $attributes
* #param array $options
* #return static
*/
public static function create(array $attributes, array $options = array())
{
$model = new static($attributes);
$model->save($options);
return $model;
}
}
Have your Asset and Product models (and others, if desired) extend BaseModel rather than Eloquent, and set the $touches attribute:
Asset.php (and other models):
class Asset extends BaseModel {
protected $touches = [ 'products' ];
...
In your seeders, set the 2nd parameter of create to an array which specifies 'touch' as false:
Asset::create([...],['touch' => false])
Explanation:
Eloquent's save() method accepts an (optional) array of options, in which you can specify two flags: 'timestamps' and 'touch'. If touch is set to false, then Eloquent will do no touching of related models, regardless of any $touches attributes you've specified on your models. This is all built-in behavior for Eloquent's save() method.
The problem is that Eloquent's create() method doesn't accept any options to pass along to save(). By extending Eloquent (with a BaseModel) to accept the $options array as the 2nd attribute, and pass it along to save(), you can now use those two options when you call create() on all your models which extend BaseModel.
Note that the $options array is optional, so doing this won't break any other calls to create() you might have in your code.