php Laravel 从多对多关系中获取数据
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Laravel get data from many to many relation
提问by Jasper Poppe
For a school project, I'm creating a website in the Laravel framework. I can't work with the data from a many-to-many table in my controller.
对于学校项目，我正在 Laravel 框架中创建一个网站。我无法处理控制器中多对多表中的数据。
Here are my models:
这是我的模型：
class Item extends Eloquent {
public function Tags()
{
return $this->belongsToMany('Tag', 'items_has_tags', 'items_id', 'tags_id');
}
}
class Tag extends Eloquent {
public function LearningMaterials()
{
return $this->belongsToMany('LearningMaterial', 'learning_materials_has_tags', 'tags_id', 'learning_materials_id');
}
}
I want to iterate all tags from my items in my controller:
我想从我的控制器中的项目中迭代所有标签：
//get all items
$all = Item::where('public', '1')->get();
foreach($allLm as $item){
$tags = $item->Tags();
var_dump('will iterate');
foreach($tags as $t){
var_dump('will not iterate');
}
}
What is wrong with my code? How can I handle the tags from my items?
我的代码有什么问题？我如何处理我的物品中的标签？
FYI: I'm creating a search engine. If the user inserts an input value like "mana", all items with tag "management" should be shown.
仅供参考：我正在创建一个搜索引擎。如果用户插入像“mana”这样的输入值，则应显示所有带有“management”标签的项目。
回答by Robo Robok
Laravel's belongsToManymethod queriesrelated models and doesn't get them. That's because you might want to have some additional constraints in your query. What you need to do is:
Laravel 的belongsToMany方法查询相关模型并没有得到它们。那是因为您可能希望在您的查询中有一些额外的约束。你需要做的是：
$tags = $item->Tags()->get();
Or simply:
或者干脆：
$tags = $item->Tags;
回答by lukasgeiter
Calling the relationship function will return a relation object(in this case an instance of BelongsToMany). You can use this to run add further components to your query before running it.
For example:
调用关系函数将返回一个关系对象（在本例中为 的实例BelongsToMany）。您可以使用它在运行之前运行将更多组件添加到您的查询中。
例如：
$only4Tags = $item->Tags()->take(4)->get();
If you want the resultof your relation, call get()or simpler, just use the magic property:
如果你想要你的关系的结果，调用get()或更简单，只需使用魔法属性：
$tags = $item->Tags()->get();
$tags = $item->Tags;
