我正在尝试使用laravel框架制作基本的简单CRUD，我设法制作了没有选择形式的简单CRUD，但是当我使用选择形式时，却收到错误消息

完全错误

SQLSTATE
[23000]：完整性约束违规：1452不能添加或更新子行，外键约束失败（activity_report_2015-04-22。tn_project，约束fk_client_id外键（cv_client_id）参考tn_client（cn_id））（SQL：INSERT
INTO
tn_project（cv_created_by，cn_created_at，cv_id，cv_name，cv_client_id，cn_invoice_method，cn_project_rate，cn_note）值（ada，2016-02-18
23:52:45，TestProject，TestName，$ client-> cn_id，$ invoice->
cn_id，1.2，JustTest））

的价值 cv_client_id 和 cv_invoice_method 来自不同的表，该表是 tn_client 和
tn_invoice_method ，我注意到，为什么价值 cv_client_id 和 cv_invoice_method
结果查询比Rathen市的价值，任何想法？

如果你们需要更多信息，请告诉我

看法

<div class="form-group">
    <label class="col-md-3 control-label">Client</label>
    <div class="col-md-9">
        <select name="clientId" id="clientId" class="form-control" placeholder="Select Client">   
            @foreach ($clients as $client) 
                <option value='$client->cn_id'>{{$client->cv_name}}</option>;   
            @endforeach     
        </select>
    </div>
</div>
<div class="form-group">
    <label class="col-md-3 control-label">Invoice Method</label>
    <div class="col-md-9">
        <select type="hidden" name="invoiceId" id="invoiceId" class="form-control">
            @foreach ($invoices as $invoice) 
                <option value='$invoice->cn_id'>{{$invoice->cv_method}}</option>;   
            @endforeach 
        </select>
    </div>
</div>

控制器

public function createOrEdit(){
    $currentUsername = Auth::user()->name;

    $isUpdate = false;
    $projectId = Input::get('prevId');

    //populate data
    $project = new Project;
    if($projectId != ""){
        $project = Project::where('cv_id','=',$projectId)->firstOrFail();
        $project->cv_updated_by = $currentUsername;
        $project->cn_updated_at = Carbon::now();
        $isUpdate = true;
    } else{
        $project->cv_created_by = $currentUsername;
        $project->cn_created_at = Carbon::now();
    }

    $project->cv_id = Input::get('projectId');
    $project->cv_name = Input::get('projectName');
    $project->cv_client_id = Input::get('clientId');
    $project->cn_invoice_method = Input::get('invoiceId');
    $project->cn_project_rate = Input::get('projectRate');
    $project->cn_note = Input::get('note');

    //execute
    if($isUpdate){
        Log::info("entering update mode");
        Project::where('cv_id','=',$projectId)->update(['cv_id'=>$project->cv_id,
                    'cv_name'=>$project->cv_name,
                    'cv_client_id'=>$project->cv_client_id,
                    'cn_invoice_method'=>$project->cn_invoice_method,
                    'cn_project_rate'=>$project->cn_project_rate,
                    'cn_note'=>$project->cn_note,
                    'cn_updated_at'=>$project->cn_updated_at,
                    'cv_updated_by'=>$project->cv_updated_by]);
    }else{
        $project->save();
    }

    return Response::json(
            array(
                    'content' => Project::with('client','invoice')->get(),
                    'status' => 'success',
                )
        );
}

注意：如果我在控制器中手动输入了 cv_client_id 和 cv_invoice_method的 值，则可以正常工作