Question

我是Django初学者，面对这个错误“music_song.album_id可能不是NULL”，我试图解决这个错误，但遗憾的是无法解决它。我把几乎所有的代码放在这里，所以请Django专家审查代码并告诉我从哪里做错了？

Views.py

def model_form_upload(request, pk):
    all_song = Song.objects.all()
    print'\n-------------------------------------------------------'
    if request.method == 'POST':
        print request.FILES
        form = SongForm(request.POST, request.FILES)
        if form.is_valid():
            songName = request.FILES['audio_file'] #getting song name
            fs = FileSystemStorage() #allocate memory
            uploaded_file_url = fs.url(songName) #getting url of uploaded file
            form.save() #song saved

            return render(request, 'music/model_form_upload.html', {'uploaded_file_url': uploaded_file_url, 
                                                              'form': form})
    else:
        form = SongForm()
    return render(request, 'music/model_form_upload.html', {'form': form, 'all_song': all_song})

forms.py

class SongForm(forms.ModelForm):
    class Meta:
        model = Song
        fields = ('song_title', 'audio_file')

models.py

from django.db import models
from django.core.urlresolvers import reverse
from .validators import validate_file_extension


class Album(models.Model):
    artist = models.CharField(max_length=100)
    album_title = models.CharField(max_length=100)
    genre = models.CharField(max_length=100)
    album_logo = models.FileField()

    def get_absolute_url(self):
        return reverse('music:upload', kwargs={'pk': self.pk})

    def __str__(self): 
        return self.artist


class Song(models.Model):
    album = models.ForeignKey(Album, on_delete=models.CASCADE)
    song_title = models.CharField(max_length=250, blank=True)
    audio_file = models.FileField(validators=[validate_file_extension], max_length=500)
    uploaded_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.song_title

urls.py

url(r'^(?P<pk>[0-9]+)/upload/$', views.model_form_upload, name='upload')

model_form_upload.html

 <form method="post" enctype="multipart/form-data">
    {% csrf_token %}
    {{ form.as_p }}
    <button type="submit">Upload</button>
  </form>



 {% if uploaded_file_url %}
        <strong>Song:</strong>
        <audio controls>
            <source src="{{ uploaded_file_url }}" type="audio/mpeg">
        </audio>


          <h2>Modal Example</h2>
          <!-- Trigger the modal with a button -->
          <button type="button" class="btn btn-info btn-lg" data-toggle="modal" data-target="#myModal">Open Modal</button>

          <!-- Modal -->
          <div class="modal fade" id="myModal" role="dialog">
            <div class="modal-dialog">

              <!-- Modal content-->
              <div class="modal-content">
                <div class="modal-header">
                  <button type="button" class="close" data-dismiss="modal">&times;</button>
                  <h4 class="modal-title">Modal Header</h4>
                </div>
                <div class="modal-body">
                  <p>Some text in the modal.</p>
                  <strong>Song:</strong>
        <audio controls>
            <source src="{{ uploaded_file_url }}" type="audio/mpeg">
        </audio>

                </div>
                <div class="modal-footer">
                  <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
                </div>
              </div>

            </div>
          </div>

{% endif %}

Answer 1

没有将album_id传递到您的上下文中，因此弹出此错误消息。因此，在您的模型中添加一个专辑字段。

<强> forms.py

class SongForm(forms.ModelForm):
    class Meta:
        model = Song
        fields = ('song_title', 'audio_file', 'album')

然后在您的视图中获取相册并将album.id传递到您的上下文中。

<强> views.py

def model_form_upload(request, pk):
    all_song = Song.objects.all()
    print'\n-------------------------------------------------------'
    if request.method == 'POST':
        print request.FILES
        form = SongForm(request.POST, request.FILES)
        if form.is_valid():
            album = request.POST['album'] #getting the album object
            songName = request.FILES['audio_file'] #getting song name
            fs = FileSystemStorage() #allocate memory
            uploaded_file_url = fs.url(songName) #getting url of uploaded file
            form.save() #song saved

            return render(request, 'music/model_form_upload.html', {'uploaded_file_url': uploaded_file_url, 'form': form, 'id': album.id})
    else:
        form = SongForm()
    return render(request, 'music/model_form_upload.html', {'form': form, 'all_song': all_song})

希望有所帮助

Answer 2

这只是因为您尝试创建没有Album实例的歌曲，根据您的模型结构album = your models.ForeignKey(Album, on_delete=models.CASCADE)，您设置了专辑字段non-null，因此{{1不能保持为空或空。

您可以将该字段设置为可空，而不是ForeignKey，只需将models.CASCADE加信号models.SET_NULL添加到相册即可删除所有相关歌曲。

/pre_delete/post_delete

或者您可以在歌曲中使用字段class Album(models.Model): artist = models.CharField(max_length=100) ''' codes ''' class Song(models.Model): album = models.ForeignKey(Album, on_delete=models.SET_NULL, null=True,blank=True) @receiver(pre_delete, sender=Album) def delete_songs_with_album(sender, instance, *args, **kwargs): instance.song_set.all().delete()，而不是通过删除该字段来稍微更改模型结构，并在album = models.ForeignKey(Album, on_delete=models.CASCADE)中添加新字段ManyToManyField 1}}

Song

在后一种情况下，您仍然可以使用相册删除所有歌曲

IntegrityError：music_song.album_id可能不为NULL

2 个答案: