为什么我不能使用我的JSON数据？

Question

我想从AJAX函数读取一些JSON数据。这里是我使用AJAX：

   $.ajax({ 
       type: 'POST', 
       cache: false, 
       url: 'Default.aspx/GetCoords', 
       data: "{}", 
       contentType: 'application/json; charset=utf-8', 
       dataType: 'json', 
       success: function (data) { 
        var text = JSON.stringify(data); 
        $("#jsonData").html(text); 
        alert(text); 
       }, 
       error: function (xhr, ajaxOptions, thrownError) { 
        alert(xhr.status); 
        alert(thrownError); 
       } 
      }); 

我也有到位的字符串化使用JSON.parse和对象返回undefined或根本没有。这是来自一个C＃的功能，看起来像这样：

[WebMethod] 
    [ScriptMethod] 
    public static string GetCoords() 
    { 
     DataTable dt = new DataTable(); 
     using (SqlConnection con = new SqlConnection(connectionString)) 
     { 
      using (SqlCommand cmd = new SqlCommand("SELECT TOP 10 * FROM DRAW ORDER BY DrawID DESC;", con)) 
      { 
       con.Open(); 
       SqlDataAdapter da = new SqlDataAdapter(cmd); 
       da.Fill(dt); 
       JavaScriptSerializer serializer = new JavaScriptSerializer(); 
       List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>(); 
       Dictionary<string, object> row; 
       foreach (DataRow dr in dt.Rows) 
       { 
        row = new Dictionary<string, object>(); 
        foreach (DataColumn col in dt.Columns) 
        { 
         row.Add(col.ColumnName, dr[col]); 
        } 
        rows.Add(row); 
       } 
       System.Diagnostics.Debug.WriteLine(serializer.Serialize(rows)); 
       return serializer.Serialize(rows);     
      } 
     } 
    } 

它返回JSON数据：这里是什么样子的调试器控制台，当我调用该函数在一个段落标签：

[{"DrawID":925,"xCoord":466,"yCoord":201},{"DrawID":924,"xCoord":385,"yCoord":318},{"DrawID":923,"xCoord":768,"yCoord":159},{"DrawID":922,"xCoord":543,"yCoord":214},{"DrawID":921,"xCoord":329,"yCoord":172}] 

然而，当我将其发送到段落标记在JQuery中或把它在一个HTML段落，这里是什么样子：

{"d":"[{\"DrawID\":925,\"xCoord\":466,\"yCoord\":201},{\"DrawID\":924,\"xCoord\":385,\"yCoord\":318},{\"DrawID\":923,\"xCoord\":768,\"yCoord\":159},{\"DrawID\":922,\"xCoord\":543,\"yCoord\":214},{\"DrawID\":921,\"xCoord\":329,\"yCoord\":172}]"} 

我有两个问题： （1）为什么我无法使用这些数据将xCoords和yCoords插入到画布中？我尝试了很多格式：（data.d [0] .xCoord，d [0] .xCoord，text.d [0] .xCoord，text [0] .xCoord等等）。 （2）上面的第二种格式是否会在试图提取用于在画布上绘画的数据时出现问题（这是我想知道的反斜杠）？

谢谢。

Answer 1

在你的成功的功能，你不字符串化或json.Parse的“数据”变量，而是data.d变量。 'd'是您需要解析的json返回的成员。

因此，改变var text = JSON.stringify(data);到var text = JSON.stringify(data.d);，你应该是金。

Answer 2

您需要使用parseJSON，因为这样的：

myThing = {"d":"[{\"DrawID\":925,\"xCoord\":466,\"yCoord\":201},{\"DrawID\":924,\"xCoord\":385,\"yCoord\":318},{\"DrawID\":923,\"xCoord\":768,\"yCoord\":159},{\"DrawID\":922,\"xCoord\":543,\"yCoord\":214},{\"DrawID\":921,\"xCoord\":329,\"yCoord\":172}]"}; 

myJSON = $.parseJSON(myThing.d); 
alert (myJSON[0].DrawID); //etc 

Answer 3

[WebMethod] 
[ScriptMethod] 
public static Dictionary<string, object>[] GetCoords() 
{ 
    DataTable dt = new DataTable(); 
    using (SqlConnection con = new SqlConnection(connectionString)) 
    { 
     using (SqlCommand cmd = new SqlCommand("SELECT TOP 10 * FROM DRAW ORDER BY DrawID DESC;", con)) 
     { 
      con.Open(); 
      SqlDataAdapter da = new SqlDataAdapter(cmd); 
      da.Fill(dt); 
      JavaScriptSerializer serializer = new JavaScriptSerializer(); 
      List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>(); 
      Dictionary<string, object> row; 
      foreach (DataRow dr in dt.Rows) 
      { 
       row = new Dictionary<string, object>(); 
       foreach (DataColumn col in dt.Columns) 
       { 
        row.Add(col.ColumnName, dr[col]); 
       } 
       rows.Add(row); 
      } 
      System.Diagnostics.Debug.WriteLine(serializer.Serialize(rows)); 
      return rows.ToArray();     
     } 
    } 
} 

的Java脚本：

  $.ajax({ 
      type: 'POST', 
      cache: false, 
      url: 'Default.aspx/GetCoords', 
      data: "{}", 
      contentType: 'application/json; charset=utf-8', 
      dataType: 'json', 
      success: function (data) { 

       $.each(data, function(index, value) { 
        var x = value.xCoord; 
        /// do something with it ;) 
       }); 
       var text = JSON.stringify(data); 
       $("#jsonData").html(text); 
       alert(text); 
      }, 
      error: function (xhr, ajaxOptions, thrownError) { 
       alert(xhr.status); 
       alert(thrownError); 
      } 
     }); 

Answer 4

我必须在我的C＃代码@lujcon返回行说：

[WebMethod] 
[ScriptMethod] 
public static List<Dictionary<string, object>> GetCoords() 
{ 
    DataTable dt = new DataTable(); 
    using (SqlConnection con = new SqlConnection(connectionString)) 
    { 
     using (SqlCommand cmd = new SqlCommand("SELECT TOP 10 * FROM DRAW ORDER BY DrawID DESC;", con)) 
     { 
      con.Open(); 
      SqlDataAdapter da = new SqlDataAdapter(cmd); 
      da.Fill(dt); 
      JavaScriptSerializer serializer = new JavaScriptSerializer(); 
      List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>(); 
      Dictionary<string, object> row; 
      foreach (DataRow dr in dt.Rows) 
      { 
       row = new Dictionary<string, object>(); 
       foreach (DataColumn col in dt.Columns) 
       { 
        row.Add(col.ColumnName, dr[col]); 
       } 
       rows.Add(row); 
      } 
      System.Diagnostics.Debug.WriteLine(serializer.Serialize(rows)); 
      return rows;     
     } 
    } 
} 

然后，我有我的var text = JSON.stringify(data);改变变种文字= JSON.stringify(data.d);正如@JustinRusso所说。现在工作。感谢大家。