在Laravel中合并foreach中的数据

Question

I create function inside Model. Variable $category=1,2,3; is string

I want that function to look in table categories and to return me name of this ids in one variable to be like $categoryName=first,second,third

public function getCategory($category){
    $names = explode(",",$category);

    foreach ($names as $name){
        $categories = DB::table('categories')->where('id',$name)->first();
        $categoryName = implode(',',(array)$categories->name);
    }
    return $this->$categoryName;
}

Answer 1

Simply, what you want to do can be done as following.

public function getCategory($categoryIds) // ex) 1,2,3
{

    $categoryIdArray = explode(",", $categoryIds); // [1,2,3]
    $categoryName = '';
    foreach ($categoryIdArray as $categoryId){
      $category = DB::table('categories')->where('id',$categoryId)->first();
      $categoryName .= $category->name . ',';
    }
    $categoryName = substr($categoryName, 0, -1);
    return $categoryName;
}

However, the example above don't make use of the advantage of Model.

Does the Model which have getCategory method have category_ids attribute?

If it is, you can write as follows.

public function getCategory()
{

    $categoryIdArray = explode(",", $this->category_ids);
    $categoryName = '';
    foreach ($categoryIdArray as $categoryId){
      $category = DB::table('categories')->where('id',$categoryId)->first();
      $categoryName .= $category->name . ',';
    }
    $categoryName = substr($categoryName, 0, -1);
    return $categoryName;
}

You can access category_ids which have 1,2,3 value for instance via $this so it doesn't need argument.

To do moreover effectively, you can have category_id attribute in another model.

In that case, you can do above more simply.

Reference: https://laravel.com/docs/5.4/eloquent-relationships#many-to-many