如何访问模型与哪些条件有多重关系？

I think that this is the correct way:

class Game extends Eloquent {
// many more stuff here


// relation without any constraints ...works fine
public function videos() {
return $this->hasMany('Video');
}


// results in a "problem", se examples below
public function available_videos() {
return $this->videos()->where('available','=', 1);
}
}

And then you'll have to

$game = Game::find(1);
var_dump( $game->available_videos()->get() );

Just in case anyone else encounters the same problems.

Note, that relations are required to be camelcase. So in my case available_videos() should have been availableVideos().

You can easily find out investigating the Laravel source:

// Illuminate\Database\Eloquent\Model.php
...
/**
* Get an attribute from the model.
*
* @param  string  $key
* @return mixed
*/
public function getAttribute($key)
{
$inAttributes = array_key_exists($key, $this->attributes);


// If the key references an attribute, we can just go ahead and return the
// plain attribute value from the model. This allows every attribute to
// be dynamically accessed through the _get method without accessors.
if ($inAttributes || $this->hasGetMutator($key))
{
return $this->getAttributeValue($key);
}


// If the key already exists in the relationships array, it just means the
// relationship has already been loaded, so we'll just return it out of
// here because there is no need to query within the relations twice.
if (array_key_exists($key, $this->relations))
{
return $this->relations[$key];
}


// If the "attribute" exists as a method on the model, we will just assume
// it is a relationship and will load and return results from the query
// and hydrate the relationship's value on the "relationships" array.
$camelKey = camel_case($key);


if (method_exists($this, $camelKey))
{
return $this->getRelationshipFromMethod($key, $camelKey);
}
}

This also explains why my code worked, whenever I loaded the data using the load() method before.

Anyway, my example works perfectly okay now, and $model->availableVideos always returns a Collection.

I think this is what you're looking for (Laravel 4, see http://laravel.com/docs/eloquent#querying-relations)

$games = Game::whereHas('video', function($q)
{
$q->where('available','=', 1);


})->get();

//use getQuery() to add condition

public function videos() {
$instance =$this->hasMany('Video');
$instance->getQuery()->where('available','=', 1);
return $instance
}

// simply

public function videos() {
return $this->hasMany('Video')->where('available','=', 1);
}

If you want to apply condition on the relational table you may use other solutions as well.. This solution is working from my end.

public static function getAllAvailableVideos() {
$result = self::with(['videos' => function($q) {
$q->select('id', 'name');
$q->where('available', '=', 1);
}])
->get();
return $result;
}

Model (App\Post.php):

/**
* Get all comments for this post.
*/
public function comments($published = false)
{
$comments = $this->hasMany('App\Comment');
if($published) $comments->where('published', 1);


return $comments;
}

Controller (App\Http\Controllers\PostController.php):

/**
* Display the specified resource.
*
* @param int $id
* @return \Illuminate\Http\Response
*/
public function post($id)
{
$post = Post::with('comments')
->find($id);


return view('posts')->with('post', $post);
}

Blade template (posts.blade.php):

\{\{-- Get all comments--}}
@foreach ($post->comments as $comment)
code...
@endforeach


\{\{-- Get only published comments--}}
@foreach ($post->comments(true)->get() as $comment)
code...
@endforeach

I have fixed the similar issue by passing associative array as the first argument inside Builder::with method.

Imagine you want to include child relations by some dynamic parameters but don't want to filter parent results.

Model.php

public function child ()
{
return $this->hasMany(ChildModel::class);
}

Then, in other place, when your logic is placed you can do something like filtering relation by HasMany class. For example (very similar to my case):

$search = 'Some search string';
$result = Model::query()->with(
[
'child' => function (HasMany $query) use ($search) {
$query->where('name', 'like', "%{$search}%");
}
]
);

Then you will filter all the child results but parent models will not filter. Thank you for attention.

 public function outletAmenities()
{
return $this->hasMany(OutletAmenities::class,'outlet_id','id')
->join('amenity_master','amenity_icon_url','=','image_url')
->where('amenity_master.status',1)
->where('outlet_amenities.status',1);
}