Adding exceptions to laravel orm scopes - php

Question

I have a table called snippets. It contains in it, amnongst other fields, the following:
ID - autoincrement
TITLE -varchar(60)
PRETTY- varchar(60)
HTML - text
My snippet model is set up as you would expect:
class Snippet extends BaseModel
{
protected $guarded = ['id'];
protected $rules = ['html' => 'required',
'pretty' => 'required|unique'];
public function scopeFromPretty($query,$prettyUrl)
{
return $query->where('pretty', '=', $prettyUrl);
}
}
This works fine if the $prettyUrl exists.
So for instance, the following line works fine, assuming there is a record with 'faq' in the pretty field.
$article = Snippet::fromPretty("faq")->first();
However, if the pretty url field doesn't exist, then $article will be empty.
Now, I could check for this in the controller, but, in my limited laravel experience, this feels wrong. I would instead like to check in the model, but don't see how I would do that.
I have tried the following:
public function scopeFromPretty($query,$prettyUrl)
{
$article = $query->where('pretty', '=', $prettyUrl);
if ($article->count() == 0)
{$article = $query->where('pretty', '=', "lost");}
return $article;
}
The aim here is to check to see if an article was found, and if it wasn't return an article which says "Your link was invalid. Please try again", or something similar.
However, this returns an empty result set (even though the "lost" Url exists in the table. At a guess I would say that the original where query is still in force, but I wouldn't know for sure.
I have a feeling that there must be a straightforward way to do this but that I am missing it, so any pointers would be great.
Thanks

Answer 1

You may want to look at using the repository pattern. It is very popular in the Laravel community. http://vimeo.com/53029232
The aim here is to check to see if an article was found, and if it wasn't return an article which says "Your link was invalid. Please try again", or something similar.
I would also recommend throwing an exception rather than returning a row from the database. You could then catch the exception in your controller and render an alternative view. This is an example of what your code could look like.
SnippetRepositoryInterface.php
interface SnippetRepositoryInterface {
/*
* Gets snippets by pretty url.
*
* #return \Illuminate\Database\Eloquent\Collection
* #throws \Illuminate\Database\Eloquent\ModelNotFoundException
*/
public function getSnippetByPretty();
}
DbSnippetRepository.php
use Illuminate\Database\Eloquent\ModelNotFoundException;
class DbSnippetRepository implements SnippetRepositoryInteface {
/**
* #inheritDoc
*/
public function getSnippetByPretty($url)
{
if (Snippet::fromPretty($url)->count())
{
return Snippet::fromPretty($url)->get();
}
throw new ModelNotFoundException(sprintf('The snippet for "%s" could not be found.', $url));
}
}

Answer 2

It turned out to be straightforward.
When I did my original scope query, the multiple where clauses were effectively being anded together.
Instead, I needed to change the second where clause to orWhere.
public function scopeFromPretty($query,$prettyUrl)
{
$article = $query->where('pretty', '=', $prettyUrl);
if ($article->count() == 0)
{$article = $query->orWhere('pretty', '=', "lost");}
return $article;
}
Note that I couldn't just do the following:
return $query->where('pretty', '=', $prettyUrl);
->orWhere('pretty', '=', "lost");}
If you do that method, and the prettyUrl happens to be returned after the lost url, then you will get the lost url.