Question

我有以下问题：我想从后面的代码调用AktualisiereSilomethode，它应该返回一个字符串列表，但我得到的只是一个错误。似乎ajax方法不会调用代码，但我不知道为什么。我会非常幸运地得到一些帮助。如果您需要更多信息或更多代码，请写信给我。

我的代码： 1. Ajax.js

//GET-Abfrage der Silos
function GetSiloListe() {
    alert("In AJAX Aufruf");
    $.ajax({
        type: "POST",
        contentType: "application/json; charset=utf-8",
        url: "Karte.aspx/AktualisiereSilo",
        //data: "{}", (changed it)
        dataType: "json",
        success:function (data, textStatus, jQxhr) { alert("Success " + data); },
        error: function (textStatus, errorThrown) { alert("Status: " + textStatus); alert("Error: " + errorThrown); },
    });
}

我在脚本标签中的karte.aspx中的电话

function siloUpdate（）{ GetSiloListe（）; }

我的代码（karte.aspx.vb）

<WebMethod()> _
    <ScriptMethod(ResponseFormat:=ResponseFormat.Json)>

     Public Shared Function AktualisiereSilo() As String
        Dim siloModel As SiloModell = New SiloModell
        Dim siloList As List(Of SiloModell) = New List(Of SiloModell)
        Dim Datab As Database = New Database
        Dim list As String = ""
        Datab.InitializeDatabase()
        siloList = Datab.siloListQuery()

        For Each el In siloList
            list = list + el.longitude + "/" + el.latitude + ";"
        Next
        Return list
    End Function

Answer 1

Imports System.Web.Services

<WebMethod()> _
 Public Shared Function AktualisiereSilo() As String
        Dim siloModel As SiloModell = New SiloModell
        Dim siloList As List(Of SiloModell) = New List(Of SiloModell)
        Dim Datab As Database = New Database
        Dim list As String = ""
        Datab.InitializeDatabase()
        siloList = Datab.siloListQuery()
        For Each el In siloList
            list = list + el.longitude + "/" + el.latitude + ";"
        Next
        Return list
End Function

因为您的数据类型是Json。
（dataType：＆＃34; json＆＃34;）
所以试试这个以获得价值。

Public Shared Function AktualisiereSilo() As String
        'Json string
        Return "[{ ""name"": ""guest01"", ""age"": ""29"", ""height"": ""7"" }]"
End Function

function GetSiloListe() {
    alert("In AJAX Aufruf");
    $.ajax({
        type: "POST",
        contentType: "application/json; charset=utf-8",
        url: "Default.aspx/AktualisiereSilo",
        dataType: "json",
        success:function (data, textStatus, jQxhr) {
        var data = $.parseJSON(data.d);
        var numOfData = data.length; 
        for (var i = 0; i < numOfData; i++) {
              alert(data[i]["name"]);   
              alert(data[i]["age"]);    
              alert(data[i]["height"]); 
        }
        },
        error: function (textStatus, errorThrown) { alert("Status: " + textStatus); alert("Error: " + errorThrown); },
    });
}

您需要确保字符串返回格式是json类型。

Imports System.Web.Services

<WebMethod()> _
 Public Shared Function AktualisiereSilo() As String
        Dim siloModel As SiloModell = New SiloModell
        Dim siloList As List(Of SiloModell) = New List(Of SiloModell)
        Dim Datab As Database = New Database
        Dim list As String = ""
        Datab.InitializeDatabase()
        siloList = Datab.siloListQuery()
        For Each el In siloList
            list = list + el.longitude + "/" + el.latitude + ";"
        Next
        Return list
End Function

Answer 2

如果您没有发送任何内容，则无需添加数据

function GetSiloListe() {
    alert("In AJAX Aufruf");
    $.ajax({
        type: "POST",
        contentType: "application/json; charset=utf-8",
        url: "Karte.aspx/AktualisiereSilo",

        dataType: "json",
        success:function (data, textStatus, jQxhr) { alert("Success " + data); },
        error: function (textStatus, errorThrown) { alert("Status: " + textStatus); alert("Error: " + errorThrown); },
    });
}

并在你的VB中改变它

<WebMethod()>
<ScriptMethod(ResponseFormat:=ResponseFormat.Json)>
Public Shared Function AktualisiereSilo() As String
        Dim siloModel As SiloModell = New SiloModell
        Dim siloList As List(Of SiloModell) = New List(Of SiloModell)
        Dim Datab As Database = New Database
        Dim list As String = ""
        Datab.InitializeDatabase()
        siloList = Datab.siloListQuery()

        For Each el In siloList
            list = list + el.longitude + "/" + el.latitude + ";"
        Next
        Return list
    End Function

Answer 3

您必须将WebMethod添加到您的方法中才能在http响应中获得所需的结果。当您致电Karte.aspx时，它会经历here所述的完整生命周期。

通过this，我希望它能清除你的概念。

如果您不想要webmethod

，可以使用this

JQuery-Ajax不会调用VB.NET背后的代码

3 个答案: