laravel防止重复记录 [英] laravel preventing duplicate record

问题描述

如何正确检查数据库中是否已存在数据并将消息返回到视图中

How to properly check if a data already exist in DB and return message into view

$check = PropertyReservation::where('res_id', Auth::user()->res_id)->where('property_no',$reservation->property_no)->first();

        if($check){
            return redirect('/reservations')->with('success','You have an existing reservation for this item ' );
        }

        else{
            $reservation->reservation_name = $resident->resident_fname;
            $reservation->reservation_type = $request->input('reservation_type');
            $reservation->reservation_quantity = $request->input('reservation_quantity');
            $reservation->save();
        }

        return redirect('/reservations');

推荐答案

您的检查也将正常进行，就好像查询没有保留一样，它返回null，这意味着您的else块将执行.但是查询生成器上有一个更好的方法叫做exists.因此，您也可以尝试以下方法:

Your check will work as well, as if there is no reservation for your query it returns null which means your else block will execute. But there is a better method on the query builder called exists. So you can try this as well:

if(PropertyReservation::where('res_id', Auth::user()->res_id)->where('property_no',$reservation->property_no)->exists();
{
   // redirect back
}

// no need for else block as this will execute if the condition above is false
// save the reservation

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