Laravel - 通过数据透视表访问、操作和循环答案

【问题标题】：Laravel - Accessing, Manipulate and Looping Through Pivot TableLaravel - 通过数据透视表访问、操作和循环
【发布时间】：2020-02-05 15:29:57
【问题描述】：

我有两个表，users 和 like_categories 有 many-to-many 关系。 pivot table 称为 like_category_user。将两个用户数据插入db 后，这是我的pivot table 样子：https://i.imgur.com/MeeRbiV.png

我想为每个 user 计算每个不同的 category 的 amount 并将其存储在 object array 中，如下所示：

[
    {
        "User Id": 1,
        "Like Categories": [
            {
                "Category": "Chinese Restaurant"
                "Amount": 1
            },
            {
                "Category": "Korean Restaurant"
                "Amount": 2
            },
            {
                "Category": "Fast Food Restaurant"
                "Amount": 3
            },
            {
                "Category": "Italian Restaurant"
                "Amount": 1
            },
            {
                "Category": "Steakhouse Restaurant"
                "Amount": 3
            }
        ]
    },
    {
        "User Id": 2,
        "Like Categories": [
            {
                "Category": "Thai Restaurant"
                "Amount": 1
            },
            {
                "Category": "Kebab Shop"
                "Amount": 3
            },
            {
                "Category": "Pizza Place"
                "Amount": 2
            },
            {
                "Category": "Steakhouse"
                "Amount": 1
            }
        }
    }
]

我尝试将数据库中的数据存储到基于上述格式的对象数组中。但输出不是我想要的。我的代码：

public function showUserLikesData() {

        $users = User::all();

        $counter = 0;
        $countUser = 0;
        $countThatCategory = 0;
        $categoryName = '';

        foreach($users as $user) {

            $userLikesData[$countUser]['User Id'] = $user->id;

            foreach ($user->likeCategories as $likeCategory) {

                 $categoryName = $likeCategory->pivot->category_name;

                foreach ($user->likeCategories as $likeCategory) {
                    $checkCategoryName = $likeCategory->pivot->category_name;

                    if ($categoryName == $checkCategoryName) {
                           $countThatCategory++;
                    }
                }

                $userLikesData[$countUser]['Like Categories'][$counter]['Category'] = $categoryName;
                $userLikesData[$countUser]['Like Categories'][$counter]['Amount'] = $countThatCategory;

                $countThatCategory = 0;

                $counter++;
            }
            $countUser++;
            $counter=0;
        }

        return $userLikesData;
    }

我得到的object array：

[
    {
        "User Id": 1,
        "Like Categories": [
            {
                "Category": "Chinese Restaurant",
                "Amount": 1
            },
            {
                "Category": "Korean Restaurant",
                "Amount": 2
            },
            {
                "Category": "Korean Restaurant",
                "Amount": 2
            },
            {
                "Category": "Fast Food Restaurant",
                "Amount": 3
            },
            {
                "Category": "Fast Food Restaurant",
                "Amount": 3
            },
            {
                "Category": "Fast Food Restaurant",
                "Amount": 3
            },
            {
                "Category": "Italian Restaurant",
                "Amount": 1
            },
            {
                "Category": "Steakhouse",
                "Amount": 3
            },
            {
                "Category": "Steakhouse",
                "Amount": 3
            },
            {
                "Category": "Steakhouse",
                "Amount": 3
            }
        ]
    },
    {
        "User Id": 2,
        "Like Categories": [
            {
                "Category": "Thai Restaurant",
                "Amount": 1
            },
            {
                "Category": "Kebab Shop",
                "Amount": 3
            },
            {
                "Category": "Kebab Shop",
                "Amount": 3
            },
            {
                "Category": "Kebab Shop",
                "Amount": 3
            },
            {
                "Category": "Pizza Place",
                "Amount": 2
            },
            {
                "Category": "Pizza Place",
                "Amount": 2
            },
            {
                "Category": "Steakhouse",
                "Amount": 1
            }
        ]
    }
]

【问题讨论】：

等等 .. 输出有什么区别？
@AntonyMN 有一些冗余密钥。可能是因为我如何循环
也许我想问的是......你得到的和你想要的有什么区别？也就是说，解释你真正想做的事情，也许有更简单的方法，或者有一个可用的 laravel 函数
@AntonyMN 我编辑了我的帖子 :)

标签： php arrays laravel laravel-5 eloquent

【解决方案1】：

如果您需要相同的输出，只需替换它

$users = User::all();

到

$users = User::all()->toArray();

【讨论】：