Question

appointment可以包含多个状态，但appointment和status之间最后创建的关系是约会的当前状态。在我的Appointment Datatable中，我想显示相关的代理InstructionType，SignUpCustomer和最新的status。我希望paginate每页10处记录这些记录。

相关模型是：

Appointment（belongsTo agent, instruction_type and sign_up_customer, belongsToMany status）
Agent
InstructionType
SignUpCustomer

我在我的控制器中有这个查询，它会产生我发送给Datatables的结果。

$query = Appointment::with(['agent', 'instruction_type', 'sign_up_customer']);
            $query->with(['statuses' => function ($query) {
                $query->latest()->first();
            }]);
            $table = Datatables::of($query);

正在制作这两个陈述，第一个是好的，我不需要最后一个。如何优化查询以删除最后一个语句？

select `statuses`.*, `appointment_status`.`appointment_id` as `pivot_appointment_id`, `appointment_status`.`status_id` as `pivot_status_id`, `appointment_status`.`created_at` as `pivot_created_at`, `appointment_status`.`updated_at` as `pivot_updated_at` from `statuses` inner join `appointment_status` on `statuses`.`id` = `appointment_status`.`status_id` where `appointment_status`.`appointment_id` in ('2') order by `created_at` desc limit 1

select `statuses`.*, `appointment_status`.`appointment_id` as `pivot_appointment_id`, `appointment_status`.`status_id` as `pivot_status_id`, `appointment_status`.`created_at` as `pivot_created_at`, `appointment_status`.`updated_at` as `pivot_updated_at`, `appointment_status`.`appointment_id` as `pivot_appointment_id`, `appointment_status`.`status_id` as `pivot_status_id`, `appointment_status`.`created_at` as `pivot_created_at`, `appointment_status`.`updated_at` as `pivot_updated_at` from `statuses` inner join `appointment_status` on `statuses`.`id` = `appointment_status`.`status_id` where `appointment_status`.`appointment_id` in ('2') order by `created_at` desc limit 1

我也试过这个：

型号：

/**
     * @return \Illuminate\Database\Eloquent\Relations\BelongsToMany
     */
    public function statuses()
    {
        return $this->belongsToMany(Status::class, 'appointment_status')->withTimestamps();
    }

    public function latestStatus()
    {
        return $this->statuses()->latest()->first();
    }

控制器：

$query = Appointment::with(['agent', 'instruction_type', 'sign_up_customer', 'latestStatus']);
            $table = Datatables::of($query);

但是我得到了这个错误：Builder.php第2445行中的BadMethodCallException：调用未定义的方法Illuminate \ Database \ Query \ Builder :: addEagerConstraints（）

Answer 1

你能不能使用本地范围吗？ https://laravel.com/docs/5.4/eloquent#local-scopes

public class SplashActivity extends AppCompatActivity 
{
    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);

        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
        finish();
    }
}

我之前没有真正做到这一点，但我认为没有理由说它不起作用（我也不知道最终查询的优化程度如何）。

如何优化此有说服力的查询以删除类似的查询

1 个答案: