title: Graphene-Django create multiple instances
body: <p>Let's say I've got a models.py with two tables:</p>
  
  <pre><code>class Category(models.Model):
      cat = models.CharField(max_length=100)
  
  
  class Thing(models.Model):
      desc = models.CharField(max_length=100)
      category = models.ForeignKey(Category, on_delete=models.SET_NULL, null=True, blank=True)
  </code></pre>
  
  <p>and my schemas as follows:</p>
  
  <pre><code>class ThingType(DjangoObjectType):
      class Meta:
          model = Thing
  
  
  class FindThing(graphene.ObjectType):
      things = graphene.List(
          ThingType,
          search=graphene.String(),
          thing=graphene.ID(),
      )
  
      def resolve_things(self, info, thing=None, search=None, **kwargs):
          qs = Thing.objects.all()
  
          if search:
              filter = (
                  Q(desc__icontains=search)
              )
              qs = qs.filter(filter)
          if thing:
              qs = qs.filter(id=thing)
  
          return qs
  
  
  class CreateThing(graphene.Mutation):
      id = graphene.Int()
      desc = graphene.String()
      category = graphene.Field(FindCategory)
  
      class Arguments:
          desc = graphene.String()
          category = graphene.Int()
  
      def mutate(self, info, desc, category):
          thing = Thing(
              desc=desc,
              category=Category.objects.get(id=category)
          )
          thing.save()
  
          return CreateThing(
              id=thing.id,
              desc=thing.desc,
              category=thing.category_id
          )
  </code></pre>
  
  <pre><code>class CategoryType(DjangoObjectType):
      class Meta:
          model = Category
  
  
  class GetCategory(graphene.ObjectType):
      category = graphene.List(
          CategoryType,
          category=graphene.String(),
      )
  
      def resolve_category(self, info, category=None, **kwargs):
          qs = Category.objects.all()
  
          if category:
              get = (
                  Q(category__contains=category)
              )
              qs = qs.get(get)
  
          return qs
  
  
  class FindCategory(graphene.ObjectType):
      categories = graphene.List(
          CategoryType,
          search=graphene.String(),
          cat=graphene.ID(),
      )
  
      def resolve_categories(self, info, cat=None, search=None, **kwargs):
          qs = Category.objects.all()
  
          if search:
              filter = (
                  Q(cat__icontains=search)
              )
              qs = qs.filter(filter)
          if cat:
              qs = qs.filter(id=cat)
  
          return qs
  
  
  class CreateCategory(graphene.Mutation):
      id = graphene.Int()
      cat = graphene.String()
      desc = graphene.String()
  
      class Arguments:
          cat = graphene.String()
          desc = graphene.String()
  
      def mutate(self, info, cat, desc):
          category = Category(
              cat=cat
          )
          category.save()
          thing = Thing(
              desc=desc,
              category_id=category.id
          )
          thing.save()
  
          return CreateCategory(
              id=category.id,
              cat=category.cat,
              desc=thing.desc,
          )
  
  </code></pre>
  
  <p>I've managed to create a schema where one can create a new category that already links to a newly created single thing:</p>
  
  <pre><code>mutation createCategory{
    createCategory(cat:"cat7", desc:"defg"){
      id
      cat
      desc
    }
  }
  </code></pre>
  
  <p>Is it possible to create a CreateCategory django-graphene schema where one can create a category with multiple additional new things?</p>