Laravel 4: How to apply a WHERE condition to all queries of an Eloquent class?

The closest thing I found is Eloquent query scope.

Even though it requires a minor change in my code(prefixing queries) it still gives me what I'm looking with great flexibility.

Here's an example:

Create a function within the Eloquent child class:

class Post extends Eloquent {

    public function scopeApproved($query)
    {
        return $query->where('approved', '=', 1/*true*/);
    }

}

Then simply use it like this:

$approvedPosts = Post::approved()-><whatever_queries_you_have_here>;

Works perfectly. No ugly repeated WHERE function calls. easy to modify. Much easier to read(approved() makes much more sense than where('approved', '=', 1) )

The answer was given when there was no query scope feature available.

You can override the main query, only for the Post model, like

class Post extends Eloquent
{
    protected static $_allowUnapprovedPosts = false;

    public function newQuery()
    {
        $query = parent::newQuery();

        if (!static::$_allowUnapprovedPosts) {
            $query->where('approved', '=', 1);
        } else {
            static::$_allowUnapprovedPosts = false;
        }

        return $query;
    }

    // call this if you need unapproved posts as well
    public static function allowUnapprovedPosts()
    {
        static::$_allowUnapprovedPosts = true;

        return new static;
    }
}

Now, simply use anything, but unapproved users won't appear in the result.

$approvedPosts = Post::where('title',  'like', '%Hello%');

Now, if you need to retrieve all posts even unapproved ones then you can use

$approvedPosts = Post::allowUnapprovedPosts()->where('title',  'like', '%Hello%');

Update (Using the query scope):

Since, Laravel now provides Global Query Scopes, leverage that instead of this hacky solution, notice the date of this answer, it's too old and so much things changed by now.

// Using a local query scope
class Post extends Eloquent
{

    public function scopeApproved($query)
    {
        return $query->where('approved', 1);
    }
}

You can use it like:

$approvedPosts = Post::approved()->get();