Django REST framework+Vue 打造生鲜电商项目（笔记二）

（转自https://www.cnblogs.com/derek1184405959/p/8768059.html）（有修改）

接下来开始引入django resfulframework，体现它的强大之处

1、写view函数

# goods/view.py

from django.views.generic import View
from goods.models import Goods

class GoodsListView(View):
    def get(self,request):
        #通过django的view实现商品列表页
        json_list = []
        #获取所有商品
        goods = Goods.objects.all()
        for good in goods:
            json_dict = {}
            #获取商品的每个字段，键值对形式
            json_dict['name'] = good.name
            json_dict['category'] = good.category.name
            json_dict['market_price'] = good.market_price
            json_list.append(json_dict)

        from django.http import HttpResponse
        import json
        #返回json，一定要指定类型content_type='application/json'
        return HttpResponse(json.dumps(json_list),content_type='application/json')

2、配置url

from goods.view import GoodsListView

urlpatterns = [
   #商品列表页
    path('goods/',GoodsListView.as_view(),name='goods-list')
]

 访问http://127.0.0.1:8000/goods/  可以获取商品列表信息的json数据

二、django的serializer序列化model

当字段比较多时，一个字段一个字段的提取很麻烦，可以用model_to_dict，将model整个转化为dict

# goods/view.py

from django.views.generic import View
from goods.models import Goods

class GoodsListView(View):
    def get(self,request):
        #通过django的view实现商品列表页
        json_list = []
        #获取所有商品
        goods = Goods.objects.all()
       
        from django.forms.models import model_to_dict
        for good in goods:
            json_dict = model_to_dict(good)
            json_list.append(json_dict)

        from django.http import HttpResponse
        import json
        #返回json，一定要指定类型content_type='application/json'
        return HttpResponse(json.dumps(json_list),content_type='application/json')

但是这样有个问题，就是ImageFieldFile 和add_time字段不能序列化

这时就要用到django的serializers

# goods/view_base.py

from django.views.generic import View
from goods.models import Goods

class GoodsListView(View):
    def get(self,request):
        #通过django的view实现商品列表页
        json_list = []
        #获取所有商品
        goods = Goods.objects.all()
       
        import json
        from django.core import serializers
        from django.http import JsonResponse

        json_data = serializers.serialize('json',goods)
        json_data = json.loads(json_data)
        #In order to allow non-dict objects to be serialized set the safe parameter to False.
        return JsonResponse(json_data,safe=False) # 注意，这里用的JsonResponse，这样就不用json.dumps了

注意，这里的图片路径是相对路径。还有其中的goods_desc之所以会那样是因为我们后台在添加数据用的是富文本，不是文本框，因此可以上传图片啥的，保存起来就是这个效果。

django的serializer虽然可以很简单实现序列化，但是有几个缺点

　　（1）字段序列化定死的，要想重组的话非常麻烦

　　（2）从上面截图可以看出来，images保存的是一个相对路径，我们还需要补全路径，而这些drf都可以帮助我们做到

以上写了这么多只是为了引入django rest framework和简单介绍django的序列化用法，下面就是重点讲解django rest framework了

 三、3种方式实现商品列表页

1、安装djangorestframework、coreapi（drf的文档支持）、django-guardian（drf对象级别的权限支持）

2、配置def文档的url

# urls.py

from rest_framework.documentation import include_docs_urls

urlpatterns = [
    #drf文档，title自定义
    path('docs',include_docs_urls(title='仙剑奇侠传')),
]

3、配置rest_framework

#setting.py

INSTALLED_APPS = [
    'rest_framework',
]

# urls.py

urlpatterns = [
    path('api-auth/',include('rest_framework.urls')),
]

4、第一种方法：APIview方式实现商品列表页

（1）goods文件夹下面新建serializers.py

用drf的序列化实现商品列表页展示，代码如下：

# goods/serializers.py

from rest_framework import serializers


class GoodsSerializer(serializers.Serializer):
    name = serializers.CharField(required=True,max_length=100)
    click_num = serializers.IntegerField(default=0)
    goods_front_image = serializers.ImageField()

这里的serializers.py可以理解成Django中在建立验证表单Form，联系这个知识点可以有助于理解。

（2）goods/views.py

# googd/views.py

from rest_framework.views import APIView
from goods.serializers import GoodsSerializer
from .models import Goods
from rest_framework.response import Response


class GoodsListView(APIView):
    '''
    商品列表
    '''
    def get(self,request,format=None):
        goods = Goods.objects.all()
        goods_serialzer = GoodsSerializer(goods,many=True)
        return Response(goods_serialzer.data)

（3）drf的Modelserializer实现商品列表页

上面是用Serializer实现的，需要自己手动添加字段，如果用Modelserializer，会更加的方便，直接用__all__就可以全部序列化

# goods/serializers.py

from rest_framework import serializers
from .models import Goods

#Serializer实现商品列表页
# class GoodsSerializer(serializers.Serializer):
#     name = serializers.CharField(required=True,max_length=100)
#     click_num = serializers.IntegerField(default=0)
#     goods_front_image = serializers.ImageField()

#ModelSerializer实现商品列表页
class GoodsSerializer(serializers.ModelSerializer):
    class Meta:
        model = Goods
        fields = '__all__'

外键category只显示分类的id，如果我们也要把外键对应的内容也显示出来。用serializers，它还可以嵌套使用，覆盖外键字段

# goods/serializers.py

from rest_framework import serializers
from .models import Goods,GoodsCategory

#Serializer实现商品列表页
# class GoodsSerializer(serializers.Serializer):
#     name = serializers.CharField(required=True,max_length=100)
#     click_num = serializers.IntegerField(default=0)
#     goods_front_image = serializers.ImageField()


class CategorySerializer(serializers.ModelSerializer):
    class Meta:
        model = GoodsCategory
        fields = "__all__"


#ModelSerializer实现商品列表页
class GoodsSerializer(serializers.ModelSerializer):
    #覆盖外键字段
    category = CategorySerializer()
    class Meta:
        model = Goods
        fields = '__all__'

5、第二种方法：GenericView实现商品列表页

（1）mixins和generic一起使用

generic里面的GenericAPIView继承APIView，封装了很多方法，比APIView功能更强大

用的时候需要定义queryset和serializer_class
GenericAPIView里面默认为空

queryset = None

serializer_class = None
mixins里的ListModelMixin里面list方法帮我们做好了分页和序列化的工作，只要调用就好了

通过查看源码帮助自己更好的理解

class GenericAPIView(views.APIView):
    """
    Base class for all other generic views.
    """
    # You'll need to either set these attributes,
    # or override `get_queryset()`/`get_serializer_class()`.
    # If you are overriding a view method, it is important that you call
    # `get_queryset()` instead of accessing the `queryset` property directly,
    # as `queryset` will get evaluated only once, and those results are cached
    # for all subsequent requests.
    queryset = None
    serializer_class = None

    # If you want to use object lookups other than pk, set 'lookup_field'.
    # For more complex lookup requirements override `get_object()`.
    lookup_field = 'pk'
    lookup_url_kwarg = None

    # The filter backend classes to use for queryset filtering
    filter_backends = api_settings.DEFAULT_FILTER_BACKENDS

    # The style to use for queryset pagination.
    pagination_class = api_settings.DEFAULT_PAGINATION_CLASS

    def get_queryset(self):
        """
        Get the list of items for this view.
        This must be an iterable, and may be a queryset.
        Defaults to using `self.queryset`.

        This method should always be used rather than accessing `self.queryset`
        directly, as `self.queryset` gets evaluated only once, and those results
        are cached for all subsequent requests.

        You may want to override this if you need to provide different
        querysets depending on the incoming request.

        (Eg. return a list of items that is specific to the user)
        """
        assert self.queryset is not None, (
            "'%s' should either include a `queryset` attribute, "
            "or override the `get_queryset()` method."
            % self.__class__.__name__
        )

        queryset = self.queryset
        if isinstance(queryset, QuerySet):
            # Ensure queryset is re-evaluated on each request.
            queryset = queryset.all()
        return queryset

GenericAPIView部分源码