React Native+DRF项目：图片上传后cv2.imread报文件名转换错误

安全阿岳

2026-7-24

React Native + DRF 图片上传报错：TypeError: Can't convert object to 'str' for 'filename'

开发React Native前端+Django REST Framework后端应用，前端通过FormData向后端发送图片时触发错误：TypeError: Can't convert object to 'str' for 'filename'。使用本地绝对路径测试接口正常，但处理前端上传的图片时出现该错误。

前端代码

const estPrice = async () => {
        const formData = new FormData();
        console.log(Page1)
        formData.append("book_page1", {
            name: "page1.jpg",
            uri: Page1,
            type: "image/jpg",
        });
        formData.append("book_page2", {
            name: "page2.jpg",
            uri: Page2,
            type: "image/jpg",
        });
        formData.append("book_page3", {
            name: "page3.jpg",
            uri: Page3,
            type: "image/jpg",
        });

        try {
            const result = await authAxios.post("/sell/estprice", formData);
            console.log(result)
        } catch (error) {
            console.log(error);
        }
};

后端代码

class BookEstimatedPriceView(GenericAPIView):
    def post(self, request):
        data = request.data
        print(data)
        img1 = data.get('book_page1', '');
        img2 = data.get('book_page2', '');
        img3 = data.get('book_page3', '');
        print(img1)

        def rgb_to_hex(rgb_color):
            hex_color = "#"
            for i in rgb_color:
                i = int(i)
                hex_color += ("{:02x}".format(i))
            return hex_color

        # img1 = 'C:/Users/Aditya Pandit/Desktop/Image/Aditya@123/photo1.jpg'
        # img2 = 'C:/Users/Aditya Pandit/Desktop/Image/Aditya@123/photo2.jpg'
        # img3 = 'C:/Users/Aditya Pandit/Desktop/Image/Aditya@123/photo3.jpg'

        img1 = cv2.imread(img1)
        img2 = cv2.imread(img2)
        img3 = cv2.imread(img3)

        img1 = cv2.cvtColor(img1, cv2.COLOR_BGR2GRAY)
        img2 = cv2.cvtColor(img2, cv2.COLOR_BGR2GRAY)
        img3 = cv2.cvtColor(img3, cv2.COLOR_BGR2GRAY)

        n_clusters = 1
       
        list_hex = []
        img_list = [img1, img2, img3]
        for item in img_list:
            kmeans = KMeans(n_clusters)
            kmeans.fit(item)
            colors = kmeans.cluster_centers_
            labels = kmeans.labels_

            label_count = [0 for i in range(n_clusters)]

            for ele in labels:
                label_count[ele] += 1
            index_color = label_count.index(max(label_count))
        

            dict_colour_percen = {}
            print
            for index, ele in enumerate(label_count):
                #print(str(ele)+' labels with pixel value -> '),
                hex_color = rgb_to_hex(colors[index])
                #print(hex_color,)
                list_hex.append(hex_color)
                color_percen = float(ele)/len(labels)*100
                print('Percentage ->'+str(color_percen))
                dict_colour_percen[hex_color] = color_percen
                print()
            plt.show()
            print()

        list_first_index = []
        for items in list_hex:
            list_first_index.append(items[1:2])
        print(list_first_index)
        price = 200
        estimated_price = 0
        list_per = []
        for items in list_first_index:
            #for color in list_color_palette:
            if(items=='0' or items=='1'):
                list_per.append(20)
            if(items=='2'):
                list_per.append(26.3)
            if(items=='3'):
                list_per.append(32.6)
            if(items=='4'):
                list_per.append(38.9)
            if(items=='5'):
                list_per.append(45.2)
            if(items=='6'):
                list_per.append(51.5)
            if(items=='7'):
                list_per.append(57.8)
            if(items=='8'):
                list_per.append(64.1)
            if(items=='9'):
                list_per.append(70.4)
            if(items=='a'):
                list_per.append(76.7)
            if(items=='b'):
                list_per.append(83)
            if(items=='c'):
                list_per.append(89.3)
            if(items=='d'):
                list_per.append(90)
            if(items=='e'):
                list_per.append(90)
            if(items=='f'):
                list_per.append(90)
        print(list_per)
        sum = 0
        for item in list_per:
            sum+=item
        avg_per=sum/len(list_per)
        print(avg_per)
        estimated_price = price*(avg_per/100)
        print(estimated_price)
        

        data = {
            'est_price': estimated_price
        }

        return Response(data, status=status.HTTP_200_OK);

报错信息

Internal Server Error: /api/sell/estprice
Traceback (most recent call last):
  File "C:\Users\Aditya Pandit\.virtualenvs\bookmart-ySyK5Yky\Lib\site-packages\django\core\handlers\exception.py", line 55, in inner
    response = get_response(request)
               ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Aditya Pandit\.virtualenvs\bookmart-ySyK5Yky\Lib\site-packages\django\core\handlers\base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Aditya Pandit\.virtualenvs\bookmart-ySyK5Yky\Lib\site-packages\django\views\decorators\csrf.py", line 56, in wrapper_view
    return view_func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Aditya Pandit\.virtualenvs\bookmart-ySyK5Yky\Lib\site-packages\django\views\generic\base.py", line 104, in view
    return self.dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Aditya Pandit\.virtualenvs\bookmart-ySyK5Yky\Lib\site-packages\rest_framework\views.py", line 509, in dispatch
    response = self.handle_exception(exc)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Aditya Pandit\.virtualenvs\bookmart-ySyK5Yky\Lib\site-packages\rest_framework\views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "C:\Users\Aditya Pandit\.virtualenvs\bookmart-ySyK5Yky\Lib\site-packages\rest_framework\views.py", line 480, in raise_uncaught_exception
    raise exc
  File "C:\Users\Aditya Pandit\.virtualenvs\bookmart-ySyK5Yky\Lib\site-packages\rest_framework\views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Aditya Pandit\Desktop\bookmart\bookmart\sell\views.py", line 70, in post
    img1 = cv2.imread(img1)
           ^^^^^^^^^^^^^^^^
TypeError: Can't convert object to 'str' for 'filename'

解决方案

问题本质

DRF接收FormData上传的图片时，request.data.get('book_page1')返回的是InMemoryUploadedFile对象，而非本地文件路径字符串。cv2.imread()仅接受字符串路径或特定格式的文件流，直接传入对象会触发类型错误。

方法一：直接读取文件字节流转换为OpenCV格式

修改后端中读取图片的逻辑，无需保存文件到本地：

import cv2
import numpy as np

# 新增工具函数
def read_uploaded_image(uploaded_file):
    if not uploaded_file:
        return None
    # 读取文件字节并转换为numpy数组
    file_bytes = np.frombuffer(uploaded_file.read(), np.uint8)
    # 解码为OpenCV可处理的图片格式
    return cv2.imdecode(file_bytes, cv2.IMREAD_COLOR)

# 替换原有的图片读取代码
img1 = read_uploaded_image(data.get('book_page1'))
img2 = read_uploaded_image(data.get('book_page2'))
img3 = read_uploaded_image(data.get('book_page3'))

# 后续灰度转换前先判断图片是否有效
if img1 is not None:
    img1 = cv2.cvtColor(img1, cv2.COLOR_BGR2GRAY)
if img2 is not None:
    img2 = cv2.cvtColor(img2, cv2.COLOR_BGR2GRAY)
if img3 is not None:
    img3 = cv2.cvtColor(img3, cv2.COLOR_BGR2GRAY)

方法二：临时保存文件后读取路径（可选）

如果需要保留cv2.imread()的调用方式，可以先将上传文件保存到临时目录：

from django.core.files.storage import default_storage
from django.core.files.base import ContentFile

# 保存文件到临时路径
if data.get('book_page1'):
    temp_file1 = default_storage.save('temp/page1.jpg', ContentFile(data.get('book_page1').read()))
    img1 = cv2.imread(default_storage.path(temp_file1))
# img2、img3同理

# 注意：需定期清理temp目录下的临时文件，避免存储空间占用

前端额外检查

React Native中上传图片时，Android与iOS的uri格式存在差异：

Android uri通常为content://开头，axios会自动处理FormData的Content-Type，无需手动设置。
iOS uri需确保为file://前缀，确认Page1/Page2/Page3变量的格式正确。

内容的提问来源于stack exchange，提问作者Kratos

React Native+DRF项目：图片上传后cv2.imread报文件名转换错误

前端代码 #

后端代码 #

报错信息 #

解决方案 #

问题本质 #

方法一：直接读取文件字节流转换为OpenCV格式 #

方法二：临时保存文件后读取路径（可选） #

前端额外检查 #