Laravel 6-``未定义变量:值''仅在第一次出现错误 [英] Laravel 6 - `Undefined variable: value` only error in the first time

问题描述

第一次将数据从表保存到数据库时，会出现此错误.

In the first time I want to save data to database from table this error appear.

ErrorException 未定义的变量:值

ErrorException Undefined variable: value

所以我必须手动输入tinker或mysql

so I have to manually input the data from tinker or mysql

我的控制器

public function store(Request $request)

{

    $validateData = $request->validate([

        'name_device_type' => 'required|max:255',

        'signature' => 'Nullable'

    ]);



    $id = DeviceType::getidDeviceTypes();

    foreach ($id as $value);   // Error happend in this line.

    $lastdevicetypeId = $value->id;

    $newdevicetypeId = $lastdevicetypeId + 1;

    $GetnewdevicetypeId = sprintf('DT%04d', $newdevicetypeId);



    $devicetypes = new DeviceType();

    $devicetypes->idDeviceType = $GetnewdevicetypeId;

    $devicetypes->name_device_type = $request->input('name_device_type');

    $devicetypes->signature = $request->input('signature');

    $devicetypes->save();



    return redirect('/devicetypes')->with('success', 'New Device Type is added');

}

我的迁移表

public function up()
    {
        Schema::create('device_types', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->string('idDeviceType');
            $table->string('name_device_type');
            $table->mediumText('signature');
            $table->timestamps();
        });
    }

我的create.blade.php

My create.blade.php

{!! Form::open(['action' => 'DeviceTypesController@store', 'method' => 'POST']) !!}
        <div class="form-group">
            {!! Form::label('name_device_type', 'Type Device'); !!}
            {!! Form::text('name_device_type', '', ['class' => 'form-control', 'placeholder' => 'Type Device']); !!}
        </div>
        <div class="form-group">
            {!! Form::label('signature', 'Signature (Optional)'); !!}
            {!! Form::textarea('signature', '', ['id' => 'classic-ckeditor5', 'class' => 'form-control', 'placeholder' => 'Signature']); !!}
        </div>
        {{ Form::button('<i class="far fa-save"></i> Submit', ['type' => 'submit', 'class' => 'btn btn-info'] )  }}
    {!! Form::close() !!}

模型

class DeviceType extends Model
{
    // Table Name
    protected $table = 'device_types';
    // Primary Key
    protected $primaryKey = 'idDeviceTypes';
    // Timestamps
    public $timestamps = true;

    public $incrementing = false;

    public static function getidDeviceType(){
        return $getidDeviceType = DB::table('device_types')->orderBy('id','desc')->take(1)->get();
    }
}

但是如果表中有数据，此错误就会消失，而且如果我删除所有数据并使表为空，也会再次出现此错误.

But if the table has data this error disappear, also this error will appear again if I remove every data and made the table empty.

推荐答案

您可以获取表的最大'id'并将其添加1，而不必获取整个记录:

You could grab the max 'id' of the table and add 1 to it without having to grab a whole record:

...
// validation

$newdevicetypeId = DeviceType::max('id') + 1;

$GetnewdevicetypeId = sprintf('DT%04d', $newdevicetypeId);

// new DeviceType
...

可以选择创建一个模型事件，该事件可以在创建记录后设置此特定字段，因此它可以使用自己的ID.

There is the option of having a model event that can set this particular field after the record has been created so it has its own id to use.

这篇关于Laravel 6-``未定义变量:值''仅在第一次出现错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！