Django的tastypie：发布到资源具有多对多场通过关系

Question

我工作的一个API的一个项目，我有一个关系订单/产品通过OrderProducts这样的：

在models.py

class Product(models.Model): 
    ... 

class Order(models.Model): 
    products = models.ManyToManyField(Product, verbose_name='Products', through='OrderProducts') 
    ... 

class OrderProducts(models.Model): 
    order = models.ForeignKey(Order) 
    product = models.ForeignKey(Product) 
    ... 

现在，当我通过API加载顺序我想获得相关产品为好，所以我想这（与Django的tastypie）：

为了/ api.py

class OrderResource(ModelResource): 
    products = fields.ToManyField('order.api.ProductResource', products, full=True) 

    class Meta: 
     queryset = Order.objects.all() 
     resource_name = 'order' 

一切适用于列出订单资源。我通过嵌入产品数据获得订单资源。

问题是我无法使用api创建或编辑Order对象。由于我在ManytoMany关系中使用贯穿模型，所以ManyToManyField（产品）没有.add（）方法。但是tastypie正在尝试在OrderResource中的产品字段上调用.add（）时向其发布/放置数据。

{"error_message": "'ManyRelatedManager' object has no attribute 'add'", "traceback": "Traceback (most recent call last):\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 192, in wrapper\n response = callback(request, *args, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 397, in dispatch_list\n return self.dispatch('list', request, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 427, in dispatch\n response = method(request, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1165, in post_list\n updated_bundle = self.obj_create(bundle, request=request, **self.remove_api_resource_names(kwargs))\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1784, in obj_create\n self.save_m2m(m2m_bundle)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1954, in save_m2m\n related_mngr.add(*related_objs)\n\nAttributeError: 'ManyRelatedManager' object has no attribute 'add'\n"} 

Answer 1

解决方案在于覆盖资源上的save_m2m（）方法。在我的情况下，我需要manytomany领域只列出，所以重写save_m2m（）方法什么都不做。

Answer 2

既然你需要多对多场只上市，一个更好的解决办法是在OrderResource的products字段添加readonly=True。这消除了重写save_m2m方法的需要。为了完整：

class OrderResource(ModelResource): 
    products = fields.ToManyField('order.api.ProductResource', products, 
            readonly=True, full=True) 

    class Meta: 
     queryset = Order.objects.all() 
     resource_name = 'order' 

Answer 3

如果允许修改，加入auto_created = True可能会解决你的问题，即，

class OrderProducts(models.Model): 
    class Meta: 
     auto_created = True 

如果你不能改变，请尝试以下tastypie补丁。

---------------------------- tastypie/resources.py ---------------------------- 
index 2cd869e..aadf874 100644 
@@ -2383,7 +2383,20 @@ class BaseModelResource(Resource): 
        related_resource.save(updated_related_bundle) 
       related_objs.append(updated_related_bundle.obj) 

-   related_mngr.add(*related_objs) 
+   if hasattr(related_mngr, 'through'): 
+    through = getattr(related_mngr, 'through') 
+    if not through._meta.auto_created: 
+     for related_obj in related_objs: 
+      args = dict() 
+      args[related_mngr.source_field_name] = bundle.obj 
+      args[related_mngr.target_field_name] = related_obj 
+      through_obj = through(**args) 
+      through_obj.save() 
+    else: 
+     related_mngr.add(*related_objs) 
+   else: 
+    related_mngr.add(*related_objs) 

    def detail_uri_kwargs(self, bundle_or_obj): 
     """ 

在Django 1.7中，错误消息更改为“无法在指定中间模型的ManyToManyField上设置值”。解决方案是一样的。