并不是所有的代码路径都返回C#中的值错误

本文关键字：错误 返回 路径 代码 并不是 | 更新日期: 2023-09-27 18:00:06

我正试图从Page_Load事件加载我的图表，但收到错误"并非所有代码路径都返回值"，我不确定我在这里做错了什么。有人能帮忙吗。

这是我的代码：

protected void Page_Load(object sender, EventArgs e)
{
    Literal2.Text = CreateChart_2();
}    
public string CreateChart_2()
{ 
    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
    // Initialize the string which would contain the chart data in XML format
    StringBuilder xmlStr = new StringBuilder();
    // Provide the relevant customization attributes to the chart
    xmlStr.Append("<chart decimalPrecision='0' showShadow='1' showborder='1' caption='Number of Lots Assigned (YTD)' subcaption='" + result1 + "'   name='MyXScaleAnim' type='ANIMATION' duration='1' start='0' param='_xscale' showNames='1' labelDisplay='Rotate'  useEllipsesWhenOverflow='1' formatNumberScale='0'>");        
    {
        // Establish the connection with the database
        string sqlStatement = "SELECT count (ID)as TotalCount, cat_name FROM MyTable group by cat_name";
        SqlCommand cmd = new SqlCommand(sqlStatement, con);
        con.Open();
        SqlDataReader reader = cmd.ExecuteReader();
        // Begin iterating through the result set
        //SqlDataReader rst = query.ExecuteReader();

        while (reader.Read())
        {
            // Construct the chart data in XML format
            xmlStr.AppendFormat("<set label='{0}' value='{1}' link='{2}'/>", reader["cat_name"].ToString(), reader["TotalCount"].ToString(), Server.UrlEncode("DrillDown1.aspx?AppName=" + reader["cat_name"].ToString()));
        }
        // End the XML string
        xmlStr.Append("</chart>");
        // Close the result set Reader object and the Connection object
        reader.Close();
        con.Close();
        // Set the rendering mode to JavaScript, from the default Flash.
        FusionCharts.SetRenderer("javascript");
        // Call the RenderChart method, pass the correct parameters, and write the return value to the Literal tag
        Literal2.Text = FusionCharts.RenderChart(
            "FusionChartsXT/Column3D.swf", // Path to chart's SWF
            "", // Page which returns chart data. Leave blank when using Data String.
            xmlStr.ToString(), // String containing the chart data. Leave blank when using Data URL.
            "annual_revenue",   // Unique chart ID
            "640", "340",       // Width & Height of chart
            false,              // Disable Debug Mode
            true);
    }
}

并不是所有的代码路径都返回C#中的值错误

您的方法签名表明它应该返回一个string。。但是您在任何地方都没有return语句。

您的呼叫站点是：

Literal2.Text = CreateChart_2();

但你在你的功能中这样做：

Literal2.Text = FusionCharts.RenderChart(
            "FusionChartsXT/Column3D.swf", // Path to chart's SWF
            "", // Page which returns chart data. Leave blank when using Data String.
            xmlStr.ToString(), // String containing the chart data. Leave blank when using Data URL.
            "annual_revenue",   // Unique chart ID
            "640", "340",       // Width & Height of chart
            false,              // Disable Debug Mode
            true);

你有两个选择。

  1. 将函数的返回类型更改为void。这是可取的，因为您已经在方法中设置了Literal的text属性
  2. 将函数的最后一部分更改为return FusionCharts.RenderChart(....

您需要在方法中添加一个返回：

选项1-返回

protected void Page_Load(object sender, EventArgs e)
{
    Literal2.Text = CreateChart_2();
}

public string CreateChart_2()
{
    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
    // Initialize the string which would contain the chart data in XML format
    StringBuilder xmlStr = new StringBuilder();
    // Provide the relevant customization attributes to the chart
    xmlStr.Append("<chart decimalPrecision='0' showShadow='1' showborder='1' caption='Number of Lots Assigned (YTD)' subcaption='" + result1 + "'   name='MyXScaleAnim' type='ANIMATION' duration='1' start='0' param='_xscale' showNames='1' labelDisplay='Rotate'  useEllipsesWhenOverflow='1' formatNumberScale='0'>");

    {
        // Establish the connection with the database
        string sqlStatement = "SELECT count (ID)as TotalCount, cat_name FROM MyTable group by cat_name";
        SqlCommand cmd = new SqlCommand(sqlStatement, con);
        con.Open();
        SqlDataReader reader = cmd.ExecuteReader();
        // Begin iterating through the result set
        //SqlDataReader rst = query.ExecuteReader();

        while (reader.Read())
        {
            // Construct the chart data in XML format
            xmlStr.AppendFormat("<set label='{0}' value='{1}' link='{2}'/>", reader["cat_name"].ToString(), reader["TotalCount"].ToString(), Server.UrlEncode("DrillDown1.aspx?AppName=" + reader["cat_name"].ToString()));
        }
        // End the XML string
        xmlStr.Append("</chart>");
        // Close the result set Reader object and the Connection object
        reader.Close();
        con.Close();
        // Set the rendering mode to JavaScript, from the default Flash.
        FusionCharts.SetRenderer("javascript");
        // Call the RenderChart method, pass the correct parameters, and write the return value to the Literal tag
        Literal2.Text = FusionCharts.RenderChart(
            "FusionChartsXT/Column3D.swf", // Path to chart's SWF
            "", // Page which returns chart data. Leave blank when using Data String.
            xmlStr.ToString(), // String containing the chart data. Leave blank when using Data URL.
            "annual_revenue",   // Unique chart ID
            "640", "340",       // Width & Height of chart
            false,              // Disable Debug Mode
            true);
    }
    return xmlStr.ToString();
}

选项2-无回报

protected void Page_Load(object sender, EventArgs e)
{
    CreateChart_2();
}

public void CreateChart_2()
{
    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
    // Initialize the string which would contain the chart data in XML format
    StringBuilder xmlStr = new StringBuilder();
    // Provide the relevant customization attributes to the chart
    xmlStr.Append("<chart decimalPrecision='0' showShadow='1' showborder='1' caption='Number of Lots Assigned (YTD)' subcaption='" + result1 + "'   name='MyXScaleAnim' type='ANIMATION' duration='1' start='0' param='_xscale' showNames='1' labelDisplay='Rotate'  useEllipsesWhenOverflow='1' formatNumberScale='0'>");

    {
        // Establish the connection with the database
        string sqlStatement = "SELECT count (ID)as TotalCount, cat_name FROM MyTable group by cat_name";
        SqlCommand cmd = new SqlCommand(sqlStatement, con);
        con.Open();
        SqlDataReader reader = cmd.ExecuteReader();
        // Begin iterating through the result set
        //SqlDataReader rst = query.ExecuteReader();

        while (reader.Read())
        {
            // Construct the chart data in XML format
            xmlStr.AppendFormat("<set label='{0}' value='{1}' link='{2}'/>", reader["cat_name"].ToString(), reader["TotalCount"].ToString(), Server.UrlEncode("DrillDown1.aspx?AppName=" + reader["cat_name"].ToString()));
        }
        // End the XML string
        xmlStr.Append("</chart>");
        // Close the result set Reader object and the Connection object
        reader.Close();
        con.Close();
        // Set the rendering mode to JavaScript, from the default Flash.
        FusionCharts.SetRenderer("javascript");
        // Call the RenderChart method, pass the correct parameters, and write the return value to the Literal tag
        Literal2.Text = FusionCharts.RenderChart(
            "FusionChartsXT/Column3D.swf", // Path to chart's SWF
            "", // Page which returns chart data. Leave blank when using Data String.
            xmlStr.ToString(), // String containing the chart data. Leave blank when using Data URL.
            "annual_revenue",   // Unique chart ID
            "640", "340",       // Width & Height of chart
            false,              // Disable Debug Mode
            true);
    }

}

或者，如果您不想从CreateChart_2()返回任何内容，则可以将签名更改为：

public void CreateChart_2()

因此您不需要返回。

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