Add a calculated field to Laravel model query

Question

I have a controller which has a query such as this one:

$post = Post::find($id);
$comments = $post->comments;

Where a post has many comments and a comment belongs to one post. The comments model has an id,comment,tag field.

What I want to do is that for any query such as this one, the model returns the fields id, comment, tag and tag_translated, where the latter is just a translation of the tag using the Lang facade.

I could solve this by using a for on the controller which iterates over the $comments and adds the field, however Ill have to do that for every controller that requires the tag_translared field. Is there a way to ask the model to include such a field?

Solution 1

Add this in your Comment Model:

protected $appends = ['tag_translated'];

public function getTagTranslatedAttribute()
{
    return 'the translated tag';
}

Hope this helps.

Solution 2

Yes there is? just add this to your Comment model

public function getTagTranslatedAttribute()
{
    return Lang::methodYouWish($this->tag);
}

then you can access this property from comment instance

$comment->tag_translated;

EDIT

You can modify your toArray method, just add it to Comment class

protected $appends = ['tag_translated'];

and then

$comment->toArray();

Solution 3

I was facing the same issue, and you just need to add two things:

The first one is the appends field:

protected $appends = ['field'];

The second one is the "getter":

public function getFieldAttribute()

At the end of the method name you need to add the "Attribute" suffix, and that's it.

Comments

[Mahdi Youseftabar]

stackoverflow.com/questions/17232714/… see this

[M at]

Does this answer your question? Add a custom attribute to a Laravel / Eloquent model on load?

[Jonathan]

Thanks! This will retrieve only that attribute, Id like to append it to the result obtained when invoking it through its parent model as in $post->comments. Then Id like to retrieve something like id,comment,tag,translated_tag.

[Boyd Hemphill]

I'd like to lobby for this to be the accepted answer. It is much more detailed and much more user. This is esp true after the edit.

[Jonathan]

Thanks! I learned also that if you dont add the $appends then the field is only retrieved when you specifically request for it as in $model->field.