“http://localhost:3000”已被 CORS 策略阻止：请求的资源上不存在“Access-Control-Allow-Origin”标头答案

【问题标题】：'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource“http://localhost:3000”已被 CORS 策略阻止：请求的资源上不存在“Access-Control-Allow-Origin”标头
【发布时间】：2021-02-20 22:50:50
【问题描述】：

我正在使用 Django 和 React 使用 Rest Framework 进行项目。我在 settings.py 中设置了CORS_ALLOW_ALL_ORIGINS=True 仍然收到错误Access to XMLHttpRequest at 'http://127.0.0.1:8000/api/encrypt/' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

我正在使用 axios 发布和获取请求。令人惊讶的是，即使在发出错误发布请求但获取请求失败之后。这是使用 axios 的反应文件

sendImage =()=> {
     this.activateSpinner()
     let formData = new FormData()
     formData.append('to_be_hidden', this.state.files[0], this.state.files[0].name)
     formData.append('used_to_hide', this.state.files[1], this.state.files[1].name)
     axios.post('http://127.0.0.1:8000/api/encrypt/', formData, {
         headers: {
            'accept': 'application/json',
            'content-type': 'multipart/form-data'
         }
     })
     .then(resp=>{
         this.getImageClass(resp)
         console.log(resp.data.id)
     })
     .catch(err=>{
         console.log("Code broke at send image")
         console.log(err)
     })
 }

 getImageClass =(obj)=> {
     axios.get(`http://127.0.0.1:8000/api/encrypt/${obj.data.id}/`, {
         headers: {
            'accept': 'application/json',
         }
     })
     .then(resp=>{
         this.setState({recentImage:resp})
         console.log(resp)
     })
     .catch(err=>{
        console.log("Code broke at get image")
        console.log(err)
    })
    this.deactivateSpinner()

 }

【问题讨论】：

标签： reactjs django django-rest-framework cross-domain django-cors-headers

【解决方案1】：

这绝对是后端的问题，我是说 Django。

CORS_ALLOW_ALL_ORIGINS=True 设置CORS_ALLOW_ALL_ORIGINS 值后，还需要设置ALLOWED_HOSTS 的值。例如 ALLOWED_HOSTS=['*']

请查看以下链接。

https://pypi.org/project/django-cors-headers/

https://dzone.com/articles/how-to-fix-django-cors-error

【讨论】：

【解决方案2】：

ALLOWED_HOSTS=['*']

INSTALLED_APPS = [
    'django.contrib.admin',
     ...
    'corsheaders',
   
]

MIDDLEWARE = [
    "django.middleware.security.SecurityMiddleware",
     ....
   
    "corsheaders.middleware.CorsMiddleware",
]

CORS_ORIGIN_ALLOW_ALL = True

CORS_ALLOW_CREDENTIALS = True


CORS_ALLOW_METHODS = [
    "DELETE",
    "GET",
    "OPTIONS",
    "PATCH",
    "POST",
    "PUT",
]
CORS_ALLOW_HEADERS = [
    "accept",
    "accept-encoding",
    "authorization",
    "content-type",
    "dnt",
    "origin",
    "user-agent",
    "x-csrftoken",
    "x-requested-with",
]

【讨论】：