laravel 访问模型属性
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laravel access model properties
提问by valkan
I am looking for solution how to access eloquent model items by 'alias' field. There is no problem accessing items by 'id'. But building a custom query I find myself unable to access item properties.
我正在寻找如何通过“别名”字段访问 eloquent 模型项的解决方案。通过“id”访问项目没有问题。但是构建自定义查询我发现自己无法访问项目属性。
This piece of code works perfect
这段代码完美运行
$cat = Category::find(1);
return $cat->title;
But if I am querying items with any other argument - properties are inaccessible
但是如果我用任何其他参数查询项目 - 属性是不可访问的
This code
这段代码
$cat = Category::where('alias','=','vodosnab')->get();
return $cat->title;
throws an exception
抛出异常
Undefined property: Illuminate\Database\Eloquent\Collection::$title
Could you please help.
能否请你帮忙。
回答by The Alpha
You already got the answer but here are some insights, when you use get()or all(), it returns a collection of model objects, which is an instance of Illuminate\Database\Eloquent\Collection, so here you'll get a Collectionobject
你已经得到了答案，但这里有一些见解，当你使用get()or 时all()，它返回一个模型对象的集合，它是 的一个实例Illuminate\Database\Eloquent\Collection，所以在这里你会得到一个Collection对象
$cat = Category::where('alias','=','vodosnab')->get();
Now, you can use, $cat->first()to get the first item (Category Model) from the collection and you may also use $cat->last()to get the last item or $cat->get(1)to get the second item from the collection. These methods are available in the Collectionobject.
现在，您可以使用,从集合中$cat->first()获取第一项 ( Category Model)，也可以使用$cat->last()获取最后一项或$cat->get(1)从集合中获取第二项。这些方法在Collection对象中可用。
Using the first()method like Category::where('alias','=','vodosnab')->first();will return you only a single (the first mathing item) model which is an instance of your Categorymodel. So, use all()or get()to get a collection of model objects and you can loop through the collection like:
使用first()like 方法Category::where('alias','=','vodosnab')->first();只会返回一个（第一个数学项）模型，它是模型的一个实例Category。因此，使用all()或get()获取模型对象的集合，您可以循环遍历该集合，例如：
foreach(Category::all() as $cat) { // or Category::get()
$cat->propertyName;
}
Or you may use:
或者你可以使用：
$categories = Category::where('alias','=','vodosnab')->get();
foreach($categories as $category) {
$category->propertyName;
}
Also, you may use:
此外，您可以使用：
$categories = Category::where('alias','=','vodosnab')->get();
$firstModel = $categories->first();
$lastModel = $categories->last();
$thirdModel = $categories->get(2); // 0 is first
If you need to get only one then you may directly use:
如果您只需要获得一个，那么您可以直接使用：
$category = Category::where('alias','=','vodosnab')->first();
$category->fieldname;
Remember that, if you use get()you'll get a collection of Modelobjects even if there is only one record available in the database. So, in your example here:
请记住，如果您使用get()，Model即使数据库中只有一条记录可用，您也会获得一组对象。因此，在您的示例中：
$cat = Category::where('alias','=','vodosnab')->get();
return $cat->title;
You are trying to get a property from the Collectionobject and if you want you may use:
您正在尝试从Collection对象中获取属性，如果需要，可以使用：
$cat = Category::where('alias','=','vodosnab')->get();
return $cat->first()->title; // first item/Category model's title
return $cat->last()->title; // last item/Category model's title
return $cat->get(0)->title; // first item/Category model's title
You may read this articlewritten on Laravel's Collectionobject.
您可以阅读写在's object上的这篇文章。LaravelCollection
回答by Can Geli?
get()returns a Collectionof items. You probably need first()that returns a single item.
get()返回一个Collection项目。您可能需要first()返回单个项目。
