php - 拉拉维尔 5.3 : Many to many realtionship's data

Question

我在用户和项目之间有多对多关系

关系名称为:User 模型有 projects 和 Project 模型有 users。并且格式正确。

我对数据表使用以下代码:

public function handleProjects(Request $request)
    {
        $responseData = \App\Misc::handleDatatable([
            "request" => $request,
            "model" => "\App\Project",
            "actions" => [
            "delete" => function($records) {
                foreach($records as $record) {
                    $record->delete();
                }
                return [
                "status" => "OK",
                "message" => "Successfully deleted the selected product types!",
                ];
            },
            ],
            "columns" => [
            "title" => "title",
            "users.username" => "users.username",
            "level" => "level",
            "users.username" => "users.username",
            "created_at" =>  function($value) {
                return $value->diffForHumans();
            }
            ],
            ]);
        return response()->json($responseData);
    }

请注意"users.username"=> "users.username",最后第8行，如何从users表中获取用户名？

上面提到了关系名称。

它给了我以下错误:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'users.username' in 'field list' (SQL: SELECT projects.*, categories.name AS b74HW, subcategory.name AS rLTng, users.username AS fUfHg from `projects` left join `categories` as `categories` on `categories`.`id` = `projects`.`categories_id` left join `sub_category` as `subcategory` on `subcategory`.`id` = `projects`.`subcategory_id` group by `id` order by `projects`.`id` desc limit 15 offset 0) 

Answer 1

这个错误非常直接。您没有在查询中使用联接，因此假设您有一个名为 users.username 的列，并且在 users 表中有一个名为 username 的列。

你如何称呼这种关系？像这样的东西:

$data = Users::find(1)->with('projects')->get();
//这个用户的id为1，并立即加载关系。

另外不要忘记循环遍历结果，例如:

foreach($data->projects as $project) {
...
}