Django rest framework and foreignkey

Hi,

I try to save foreign key in django restframework serializer.

My goal is to save in database information from iframely.com and this part works good. But I need to also save it in specific category. After add field "Board(my category name field)" I have error: null value in column "board_id" violates not-null constraint

Maybe here someone help me.

My model:

class Embed(models.Model):
    url = models.URLField(max_length=255)
    title = models.CharField(max_length=255)
    description = models.TextField()
    thumbnail_url = models.URLField(max_length=255)
    html = models.TextField()
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    board = models.ForeignKey(Board, on_delete=models.CASCADE, verbose_name='Kategoria')

Form:

class SubmitEmbed(forms.Form):
    url = forms.URLField()
    board = forms.ModelChoiceField(queryset=Board.objects.all())

Serializer:

class EmbedSerializer(serializers.ModelSerializer):
    author = serializers.HiddenField(default=serializers.CurrentUserDefault())
    board = serializers.RelatedField(read_only=True)

    class Meta:
        model = Embed
        fields = '__all__'

View:

def save_embed(request):

    if request.method == "POST":
        form = SubmitEmbed(request.POST)
        if form.is_valid():
            url = form.cleaned_data['url']
            r = requests.get('http://iframe.ly/api/oembed?url=' + url + '&key=' + settings.IFRAMELY_KEY)
            json = r.json()
            serializer = EmbedSerializer(data=json, context={'request': request})
            if serializer.is_valid():
                embed = serializer.save()
                return render(request, 'embed/embeds.html', {'embed': embed})
    else:
        form = SubmitEmbed()

    return render(request, 'embed/embedadd.html', {'form': form})