如何在反应中调用 Fetch post API 到 ASP.NET 通用处理程序？

Question

我正在将 ReactJS 与 ASP.NET Web 窗体一起使用，在自动完成组件的 onChange 中，调用了一个通用处理程序来更新数据源。

所以在 Autocomplete 组件的 onChange 中使用了 fetch API post call，奇怪的是有时我确实得到了响应，有时 fetch API 被阻止，如 chrome 开发人员工具中所见。在服务器端也应用了所有 CORS 标头，但不明白为什么它只是有时会失败。

错误

index.js:39 POST http://localhost:53107/INV/MKRF/Handlers/Handler.ashx net::ERR_BLOCKED_BY_CLIENT

索引.js

class App extends React.Component {

constructor(props) {
    super(props);
    this.state = {
        itemcodes: [],
        selected: null,
        qty: '',
        rows: []
    };


}


handlechange = (e) => {
    //console.log(e);
    this.setState({
        selected: e.value
    });

    var data = new URLSearchParams();
    data.append("method", "GetAllBAANItemCodes");
    data.append("prefix", this.state.selected);
    fetch('Handlers/Handler.ashx', {
        method: 'POST',
        headers: {
            Accept: "application/json",              
            "Content-Type": "application/x-www-form-urlencoded",
            "Access-Control-Request-Headers": "*",
            "Access-Control-Request-Method": "*"
            //'X-Requested-With': 'XMLHttpRequest'
        },
        credentials: "include",
        body: data
    }).then((response) => { response.json(); })
        .then((data) => { this.setState({ itemcodes: data }); })
        .catch(
            (error) => console.log(error)
        );

}



render() {
    return (
                    <Autocomplete
                        dataSource={this.state.itemcodes}
                        value={this.state.selected}
                        onValueChanged={(e) => this.handlechange(e)}
                        placeholder={'Type first name...'}
                    />


    );
}

}

处理代码

Public Class Handler : Implements IHttpHandler

Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
    Dim method As String = context.Request("method")
    If method = "GetAllBAANItemCodes" Then
        Dim prefix As String = context.Request("prefix")
        Dim conBAAN As New SqlClient.SqlConnection
        conBAAN.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings("BAAN").ConnectionString
        conBAAN.Open()
        Dim itemCodes As New List(Of String)
        Dim cmdBAAN As New SqlClient.SqlCommand
        cmdBAAN.Connection = conBAAN
        cmdBAAN.Connection = conBAAN
        cmdBAAN.CommandType = CommandType.Text
        cmdBAAN.CommandText = <some query>
        cmdBAAN.Parameters.AddWithValue("@SearchText", prefix)
        Dim rdr As SqlDataReader = cmdBAAN.ExecuteReader
        If rdr.HasRows Then
            While rdr.Read
                itemCodes.Add(rdr("t_item").ToString())
            End While
        End If

        rdr.Close()
        cmdBAAN.Dispose()
        conBAAN.Close()

        Dim js As New JavaScriptSerializer()
        context.Response.ContentType = "application/json"
        context.Response.Headers.Add("Access-Control-Allow-Origin", "*")
        context.Response.Headers.Add("Access-Control-Allow-Methods", "*")
        context.Response.Write(JsonConvert.SerializeObject(itemCodes))

Answer 1

是的，正如@sideshowbarker 所建议的那样，浏览器安装了该公司的 ForcePoint 扩展程序，该扩展程序给出了错误。