我尝试设置类别为我的职位没有一个形式，与javascript
模板：

<form enctype="multipart/form-data" method="POST" action="" accept=".mp4" style="text-align: center;">
    {% csrf_token %}
    <p style="color: gray; padding-top: 20px;">or</p>
    <select name="" id="ms" multiple="multiple">
    {% for category in categories%}
            <!-- <option type="checkbox" value="{{category}}">{{category}}</option> -->
            <input id="category" class="category" catid="{{category.id}}" type="checkbox" value="{{category.id}}">{{category}}</input>
            {% endfor %}
    </select>
    <input type="text" name="title" id="title" placeholder="Title">
    <input type="text" name="tags" id="tags" placeholder="Tags: Please separate by comma ','">
    <textarea name="description" id="description" cols="30" rows="10" placeholder="Please describe your video..."></textarea>
    <div class="form-group">
            <label>Select file to upload.</label>
            <input type="file" name="file" accept=".mp4" class="form-control" id="fileupload" placeholder="Select file">
    </div>
    <input type="submit" value="Upload" id="submit" class="btn btn-success">     
</form>

约旦：

var id_categories = []; 
    var category = document.querySelectorAll("input[type=checkbox]:checked")
    for (var i = 0; i < category.length; i++) {
        id_categories.push(category[i].value)
      }
    var formData = new FormData();
    formData.append('categories', id_categories)

我认为：

categories_1 = Category.objects.all()
if request.method == 'POST':
 categories = request.POST['categories']
 FileFolder.save()
 tag_list = taggit.utils._parse_tags(tags)
 FileFolder.tags.add(*tag_list)
 categories_post = Category.objects.filter(id__in=[categories])
            if categories_post:
                for category in categories_post:
                    FileFolder.categories.add(category)
return render(request, 'main/create_post.html', {'categories': categories_1})

它返回：
ValueError：字段"id"应为数字，但得到的却是"3，4"。
但是当我手动输入[3，4]时，它工作了，有什么想法吗？