Django REST Swagger如何指定api参数

为什么要指定swagger的api参数

api的参数有多种类型：

• query 参数，如 /users?role=admin
• path 参数，如 /users/{id}
• header 参数，如 X-MyHeader: Value
• body 参数，描述POST，PUT，PATCH请求的body
• form 参数，描述 Content-Type of application/x-www-form-urlencoded 和 multipart/form-data 的请求报文body的参数

swagger指定api参数就可以在文档相应的api条目中显示出api的描述、正常输出、异常输出、参数的名称、描述、是否必填、值类型、参数类型对不同的参数类型有不同的显示效果。swagger是可交互的api文档，可以直接填入文档显示的参数的值并发送请求，返回的结果就会在文档中显示。

难点

对 Django REST Swagger < 2 的版本，要指定swagger的api参数非常容易，只要将相关说明以特定格式和yaml格式写在相应api的视图函数的文档字符串（DocStrings）里，swagger就会自动渲染到文档中。比如这样的格式：

def cancel(self, request, id):
    """
    desc: 取消任务，进行中的参与者得到报酬
    ret: msg
    err: 404页面/msg
    input:
    - name: id
        desc: 任务id
        type: string
        required: true
        location: path
    """

但是在2.0版本之后，Django REST Swagger废弃了对yaml文档字符串的支持，不会渲染出任何内容。

一种解决方案

在Django REST framework基于类的api视图中定义filter_class过滤出模型（models）的特定字段，swagger会根据这些字段来渲染。

from django_filters.rest_framework.filterset import FilterSet

class ProductFilter(FilterSet):

    class Meta(object):
        models = models.Product
        fields = (
            'name', 'category', 'id', )


class PurchasedProductsList(generics.ListAPIView):
    """
    Return a list of all the products that the authenticated
    user has ever purchased, with optional filtering.
    """
    model = Product
    serializer_class = ProductSerializer
    filter_class = ProductFilter

    def get_queryset(self):
        user = self.request.user
        return user.purchase_set.all()

这个解决方法只解决了一半问题，只能用在面向模型的api，只能过滤模型的一些字段，而且api参数名与模型字段名不一致时还要额外处理。

启发

查阅Django REST Swagger的文档，Advanced Usage提到，基于类的文档api视图是这样的：

from rest_framework.response import Response
from rest_framework.schemas import SchemaGenerator
from rest_framework.views import APIView
from rest_framework_swagger import renderers


class SwaggerSchemaView(APIView):
    permission_classes = [AllowAny]
    renderer_classes = [
        renderers.OpenAPIRenderer,
        renderers.SwaggerUIRenderer
    ]

    def get(self, request):
        generator = SchemaGenerator()
        schema = generator.get_schema(request=request)

        return Response(schema)

说明文档是根据schema变量来渲染的，所以可以通过重载schema变量，利用yaml包解析出api视图函数的文档字符串中的参数定义赋值给schema变量。

更好的解决方法

创建schema_view.py：

from django.utils.six.moves.urllib import parse as urlparse
from rest_framework.schemas import AutoSchema
import yaml
import coreapi
from rest_framework_swagger.views import get_swagger_view


class CustomSchema(AutoSchema):
    def get_link(self, path, method, base_url):

        view = self.view
        method_name = getattr(view, 'action', method.lower())
        method_docstring = getattr(view, method_name, None).__doc__
        _method_desc = ''

        fields = self.get_path_fields(path, method)

        try:
            a = method_docstring.split('---')
        except:
            fields += self.get_serializer_fields(path, method)
        else:
            yaml_doc = None
            if method_docstring:
                try:
                    yaml_doc = yaml.load(a[1])
                except:
                    yaml_doc = None

            # Extract schema information from yaml

            if yaml_doc and type(yaml_doc) != str:
                _desc = yaml_doc.get('desc', '')
                _ret = yaml_doc.get('ret', '')
                _err = yaml_doc.get('err', '')
                _method_desc = _desc + '\n<br/>' + 'return: ' + _ret + '<br/>' + 'error: ' + _err
                params = yaml_doc.get('input', [])

                for i in params:
                    _name = i.get('name')
                    _desc = i.get('desc')
                    _required = i.get('required', False)
                    _type = i.get('type', 'string')
                    _location = i.get('location', 'form')
                    field = coreapi.Field(
                        name=_name,
                        location=_location,
                        required=_required,
                        description=_desc,
                        type=_type
                    )
                    fields.append(field)
            else:
                _method_desc = a[0]
                fields += self.get_serializer_fields(path, method)

        fields += self.get_pagination_fields(path, method)
        fields += self.get_filter_fields(path, method)

        manual_fields = self.get_manual_fields(path, method)
        fields = self.update_fields(fields, manual_fields)

        if fields and any([field.location in ('form', 'body') for field in fields]):
            encoding = self.get_encoding(path, method)
        else:
            encoding = None

        if base_url and path.startswith('/'):
            path = path[1:]

        return coreapi.Link(
            url=urlparse.urljoin(base_url, path),
            action=method.lower(),
            encoding=encoding,
            fields=fields,
            description=_method_desc
        )


schema_view = get_swagger_view(title='API')

urls.py中指向schema_view：

from .schema_view import schema_view

urlpatterns = [
    url(r'^v1/api/', include([
        url(r'^doc/', schema_view),
    ])),

然后在需要指定api参数的视图类（如APIView或ModelViewSet）中重载schema：

schema = CustomSchema()