输入在laravel 5.3上发送NULL数组

Question

i have this error when I try to send an array to my database table. i have this on my update method

$post = Post::findOrFail($id);
$post->PostTitle = $request->PostTitle;
$post->post = $request->post;

$tags = new Tag;

foreach ($request->tags as $tags) {

    $tag = Tag::create(['tag' => $tags]);

    if ($tag->save()) {
        $post->tags()->sync($tag->id);
    }
}

this is my html form

<div class="post-panel-3">
        <div class="form-group">
          <label for="postTags">Etiquetas: </label>
            <input type="text" name="tags[]" class="form-control" placeholder="Etiquetas" value="<?php if(isset($post->tags)){ foreach($post->tags as $tag); echo $tag->tag;} ?>" id="tagBox2">

I have ManyToMany relationship model, all run fine in create method but no on update. I think i miss something but not finded yet.

Answer 1

The sync() method takes an array as parameter. You are passing an object.

Create an array of IDs first, then pass it to the sync function.

$ids = [];
foreach ($request->tags as $tags) {
    $tag = Tag::create(['tag'=>$tags]);
    $ids[] = $tag->id;
}

//sync 
$post->tags()->sync($ids); //array of ids