在数据透视表 laravel 中删除行和插入行

Question

您好，当出现以下情况时，我正在尝试更新我的 tagtask 表（数据透视表）：

例如，我们已经有一个包含 3 个标签的任务，例如营销、开发、会计。现在我们要编辑该任务并删除这 3 个标签并添加 1 个名为 Cooking 的标签。

所以我已经想到的是从 tagtask 表中删除这 3 个标签并添加标签“烹饪” 在 tagtask 表中。此外，我不会从标签表中删除标签，因为可能有一些任务使用市场营销、开发或会计标签。

不幸的是，关于第一部分我的想法我无法实现。为了向您展示我的尝试，我将首先向您展示我的一段代码：

{{Form::model($task,array('route'=>array('user.tasks.update', $task->id), 'method'=>'put'))}}
    <ul>
        <li>
                {{Form::label('tag', 'tags')}}
                <input type="text" name="tag_name" class="form-control" value='@foreach($task->tagtask as $tt){{$tt->tag['tag_name']}} @endforeach'>
        </li>
        <li>
                {{Form::submit('Edit Task',  array('class' => 'btn btn-default'))}}
        </li>
    </ul>
{{Form::close()}}

这是我的TaskController.php，其中包含以下代码：

<?php 
public function update($id)
    {
        $task = Task::findOrFail($id);
        $str = Input::get('tag_name');
        //Split string by a regular expression
        $arrayTags = preg_split('/[, ;]/', $str);

        $tt_current = Tagtask::where('id_task', $id)->get();
        $tags_raw = Tag::all();
        $tags =  array();

        foreach($tags_raw as $tag) 
        {   
            $tags[$tag->tag_name] = $tag->id;
        }

        foreach($arrayTags as $tag) 
        {

            if(!isset($tags[$tag])){
                //The tag doesn't exist. So we store a tag and get a new ID.
                        $id_tag=DB::table('tags')->insertGetId(
                                array('tag_name' => $tag)
                                );

                        $data_TagTask= array(
                                'id_task' => $id,
                                'id_tag' => $id_tag
                                );

                        $id_tagtask=DB::table('tagtasks')->insertGetId($data_TagTask);
                        $row= DB::table('tagtasks')->where('id', $id_tagtask)->first();

            } else {
                //The tag does exist
                foreach($tt_current as $tt) 
                {   //the following below is maybe wrong..
                    if ($tt->id_tag ==  $tags[$tag] && $tt->id_task == $row->id_task ) {
                        Tagtask::destroy($row->id_task);
                    }
                    //$tags[$tag->tag_name] = $tag->id;
                    //if(isset($tags_current[$id_task]))
                    //unset($tags_current[$id_task]);
                }
            }   
        }
        //print_r($tags)
        //die();
        return Redirect::route('user.tasks.index');
    }

所以我使用该代码实现的是，我可以删除视图中的 3 个标签（如前所述）并添加一个新标签进行更新。新的标签然后存储在tagtask表和tag表中，但问题是旧的3个标签还在tagtask表中。虽然他们应该被删除..有人可以帮助我吗？很高兴我在等你的答复。不管怎样，谢谢你的回答。

Answer 1

您应该为此使用sync。也许我错过了什么，但代码应该是这样的：

public function update($id)
{
    $task = Task::findOrFail($id);
    $str = Input::get('tag_name');
    //Split string by a regular expression
    $arrayTags = preg_split('/[, ;]/', $str);

    $tagIds = [];
    foreach ($arrayTags as $tag) {
        // here you can apply trim or skipping empty tags
        $fTag = Tag::firstOrCreate(['tag_name' => $tag]);
        $tagIds[] = $fTag->id;
    }

    $task->tags()->sync($tagIds);

    return Redirect::route('user.tasks.index');
}

当然，tags 模型需要有 tags 关系

Answer 2

我为感兴趣的人提供解决方案。唯一的更改是在 TaskController.php 中进行的。下面是带有cmets的代码，方便大家理解：

<?php 
public function update($id)
    {
        $str = Input::get('tag_name');
        //Split string by a regular expression
        $inputTags = preg_split('/[, ;]/', $str);

        $tt_current = Tagtask::where('id_task', $id)->get();
        $oldTaskTagsToDestroy = array();

        $tags_raw = Tag::all();
        $tags =  array();

        foreach($tt_current as $item) 
        {   //id_tag is the key with the tagtaskID as value.
            $oldTaskTagsToDestroy[$item->id_tag] = $item->id;
        }

        foreach($tags_raw as $tag) 
        {   //tag_name is the key with the tagID as value.
            $tags[$tag->tag_name] = $tag->id;
        }

        foreach($inputTags as $tag) 
        {
            if(!isset($tags[$tag]))
                /* At first in $tag lives the name of the tag that was given through
                input from a user. After that we return the id through the insertGetId() method and
                put in $tags[$tag]*/
                $tags[$tag] = DB::table('tags')->insertGetId(
                    array('tag_name' => $tag)
                );

                //for example tagtask ID 40 exists, so we don't execute the body of the if statement
            if(!isset($oldTaskTagsToDestroy[ $tags[$tag] ])){

                $data_TagTask= array(
                        'id_task' => $id,
                        'id_tag' => $tags[$tag]
                        );

                DB::table('tagtasks')->insertGetId($data_TagTask);

            } else 
                /*So we remove the key and the value of tagtask ID 40, because it's again present in the new input.
                We must do this, so that the old tasktags ID's will not be deleted from the tagtask table.*/
                unset( $oldTaskTagsToDestroy[ $tags[$tag] ] );
        }
        //And here we remove old tagtask ID's that aren't present anymore/again with the new input. So we delete them from the database.
        foreach($oldTaskTagsToDestroy as $key => $value) 
        {   
                Tagtask::destroy($value);
        }

        return Redirect::route('user.tasks.index');
    }

说实话，我得到了实习主管的帮助。我是一家构建 Web 应用程序的公司的实习生。我正在尽我最大的努力成为一名优秀的程序员。