虽然我在.NET和Javascript方面很有经验,但我目前正在学习React,在获取REST API的过程中,我得到了这个错误。
CORS策略已阻止从源“http://localhost:3000”在“https://localhost:7142/api/Campaign”进行提取的访问:请求的资源上不存在“Access-Control-Allow-Origin”标头。如果不透明响应满足您的需要,请将请求的模式设置为“no-cors”以在禁用CORS的情况下提取资源。
这是我的Startup.cs
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Newtonsoft.Json.Serialization;
using Microsoft.Extensions.FileProviders;
using System.IO;
namespace WebAPI
{
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
//Enable CORS
services.AddCors(c => c.AddPolicy(name:"MyPolicy", options =>
{
options.WithOrigins("http://localhost:3000")
.AllowAnyMethod()
.AllowAnyHeader();
}));
//JSON Serializer
services.AddControllersWithViews().AddNewtonsoftJson(options =>
options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore)
.AddNewtonsoftJson(options => options.SerializerSettings.ContractResolver
= new DefaultContractResolver());
services.AddControllers();
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
app.UseRouting();
//Enable CORS
app.UseCors("MyPolicy");
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllers();
});
app.UseStaticFiles(new StaticFileOptions
{
FileProvider = new PhysicalFileProvider(
Path.Combine(Directory.GetCurrentDirectory(), "Photos")),
RequestPath = "/Photos"
});
}
}
}
我相信这个问题必须处理CORS政策,但已经尝试了一切。有什么突出的人吗?
这是我的Campaign.js
import React,{Component} from 'react';
import { variables } from './Variables';
export class Campaign extends Component{
constructor(props){
super(props);
this.state={
campaigns:[]
}
}
refreshList(){
debugger;
//fetch(variables.API_URL+'Campaign')
fetch('https://localhost:7142/api/Campaign')
.then(response=>response.json())
.then(data=>{
this.setState({campaigns:data});
console.log(data);
});
}
componentDidMount(){
this.refreshList();
}
render(){
const {
campaigns
}=this.state;
return(
<div>
<table className='table table-striped'>
<thead>
<tr>
<th>
CampaignId
</th>
<th>
CampaignName
</th>
<th>
Options
</th>
</tr>
</thead>
<tbody>
{campaigns.map(camp=>
<tr key={camp.campaign_id}>
<td>{camp.campaign_id}</td>
<td>{camp.campaign_name}</td>
<td>
<button type="button" className="btn btn-light mr-1">
<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-pencil-square" viewBox="0 0 16 16">
<path d="M15.502 1.94a.5.5 0 0 1 0 .706L14.459 3.69l-2-2L13.502.646a.5.5 0 0 1 .707 0l1.293 1.293zm-1.75 2.456-2-2L4.939 9.21a.5.5 0 0 0-.121.196l-.805 2.414a.25.25 0 0 0 .316.316l2.414-.805a.5.5 0 0 0 .196-.12l6.813-6.814z"/>
<path fill-rule="evenodd" d="M1 13.5A1.5 1.5 0 0 0 2.5 15h11a1.5 1.5 0 0 0 1.5-1.5v-6a.5.5 0 0 0-1 0v6a.5.5 0 0 1-.5.5h-11a.5.5 0 0 1-.5-.5v-11a.5.5 0 0 1 .5-.5H9a.5.5 0 0 0 0-1H2.5A1.5 1.5 0 0 0 1 2.5v11z"/>
</svg>
</button>
<button type="button" className="btn btn-light mr-1">
<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-trash-fill" viewBox="0 0 16 16">
<path d="M2.5 1a1 1 0 0 0-1 1v1a1 1 0 0 0 1 1H3v9a2 2 0 0 0 2 2h6a2 2 0 0 0 2-2V4h.5a1 1 0 0 0 1-1V2a1 1 0 0 0-1-1H10a1 1 0 0 0-1-1H7a1 1 0 0 0-1 1H2.5zm3 4a.5.5 0 0 1 .5.5v7a.5.5 0 0 1-1 0v-7a.5.5 0 0 1 .5-.5zM8 5a.5.5 0 0 1 .5.5v7a.5.5 0 0 1-1 0v-7A.5.5 0 0 1 8 5zm3 .5v7a.5.5 0 0 1-1 0v-7a.5.5 0 0 1 1 0z"/>
</svg>
</button>
</td>
</tr>
)}
</tbody>
</table>
</div>
)
}
}
export default Campaign;
2条答案
按热度按时间aiqt4smr1#
希望我能帮助你..我也是新学习React和抓取。我遇到了这个问题,以及当我试图发送'POST'请求到一个真实的数据库在firebase。我已经修复了这个错误的方法是添加'folder-name.json'在我的网址我正在抓取的结尾。
}
如果这没有帮助,我读到你需要在你的后端服务器安装CORS来获取数据。你可能会在这个网站找到有用的信息[链接]:网站名称:http://www.stackhawk.com/blog/react-cors-guide-what-it-is-and-how-to-enable-it/#:~:文本= CORS%20错误。,在%20端口%203000上的客户端%20的React。
kknvjkwl2#
是的,这确实与CORS有关,跨源资源共享。因此,本质上,API从标识为localhost的服务器获取请求,这是另一个域,因此它是对象。
这是因为.net希望你作为一个开发者选择使用外部域数据,以被动地帮助你抵御DOS攻击。你要做的是告诉.net这个地方是可以的,或者选择允许所有地方,如果你是这样的人,所以在Startup.cs中配置API时