Laravel-eloquent:调用未定义的方法Illuminate\Database\Eloquent\Collection::where()

Question

我有两个多对一关系的模型：

class Meal extends \Eloquent {
    /**
     * public Integer   $id; - primary key
     * public String    $name;
     */
    protected $fillable = array('id','name');

    public function mealProperties()
    {
        return $this->hasMany('MealProperty');
    }
}

class MealProperty extends \Eloquent {
    /**
     * public Integer   $id; - primary key
     * public Integer   $meal_id;
     */
    protected $fillable = array('id','meal_id');

    public function meal()
    {
        return $this->belongsTo('Meal', 'meal_id');
    }
}

如果我先要第一顿饭，mealProperty，一切都很好：

$mealProp = Meal::first()->mealProperties->first();

但是如果我以这种方式请求带有第一顿饭的特定id的mealProperty：

$mealProp = Meal::first()->mealProperties->where('id','=','1')->first();

我得到了这个错误：

Call to undefined method Illuminate\Database\Eloquent\Collection::where()

我在谷歌上搜索了两个小时我做错了什么，但仍然一无所获。

如果我不能使用where方法，有什么可能的方法来获取特定的mealProperty？

感谢您的帮助！

Answer 1

Laravel 5的更新：

自v5发布以来，Support\Collection对象上有一个方法where，因此这个问题/答案变得无关紧要。该方法的工作原理与filter完全相同，即。直接返回过滤后的集合：

$mealProp = Meal::first()->mealProperties->where('id','=','1'); // filtered collection

// that said, this piece of code is perfectly valid in L5:
$mealProp = Meal::first()->mealProperties->where('id','=','1')->first();

您必须区分Laravel行为：

(动态属性)雄辩的集合或模型

$meal->mealProperties

关系对象

$meal->mealProperties()

现在：

// mealProperties is Eloquent Collection and you call first on the Collection here
// so basically it does not affect db query
$mealProp = Meal::first()->mealProperties->first();

// here you try to add WHERE clause while the db query is already called
$mealProp = Meal::first()->mealProperties->where('id','=','1')->first();

// So this is what you want to do:
$mealProp = Meal::first()->mealProperties()->where('id','=','1')->first();

Answer 2

你可以试试这个：

$mealProop1 = Meal::first()->mealProperties->find(1); // id = 1

或者类似这样的东西：

$mealProops = Meal::first()->mealProperties;
$mealProop5 = $mealProops->find(5); // id = 5
$mealProop7 = $mealProops->find(7); // id = 7

而不是这样：

$mealProp = Meal::first()->mealProperties->where('id','=','1')->first();

另外，下面的代码应该可以工作：

$mealProp = Meal::first()->mealProperties->first();