c# - 对象引用未设置到数据集中对象的实例

Question

我正在使用以下代码来填充数据集

public static DataSet GetDataSetBySP(string spName)
    {
        try
        {
            using (SqlConnection conn = new SqlConnection(ConnString))
            {
                conn.Open();
                SqlCommand cmd = conn.CreateCommand();
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.CommandText = spName;
                cmd.CommandTimeout = 60;
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds);

                conn.Close();
                return ds;
            }
        }
        catch
        {
            return null;
        }
    }

我第一次调用该函数时，我只得到了第一个充满数据的表，其他表看起来像这样

Data Visualizer 中的错误类似于

DataSet Visualizer

Unhandled exception has occurred in a component in your application.If you click Continue,the application will ignore this error and attempt to continue.

Object referance not set to an instance of an object


See the end of this message for details on invoking 
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
   at EnhancedDataSetVisualizer.VisualizerCommunicator.GetTableCellValue(Int32 rowIndex, Int32 colIndex)
   at EnhancedDataSetVisualizer.DataSetForm.dataGridView_CellValueNeeded(Object sender, DataGridViewCellValueEventArgs e)
   at System.Windows.Forms.DataGridView.OnCellValueNeeded(DataGridViewCellValueEventArgs e)
   at System.Windows.Forms.DataGridView.OnCellValueNeeded(Int32 columnIndex, Int32 rowIndex)
   at System.Windows.Forms.DataGridViewCell.GetValue(Int32 rowIndex)
   at System.Windows.Forms.DataGridViewCell.PaintWork(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, Int32 rowIndex, DataGridViewElementStates cellState, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts)
   at System.Windows.Forms.DataGridViewRow.PaintCells(Graphics graphics, Rectangle clipBounds, Rectangle rowBounds, Int32 rowIndex, DataGridViewElementStates rowState, Boolean isFirstDisplayedRow, Boolean isLastVisibleRow, DataGridViewPaintParts paintParts)
   at System.Windows.Forms.DataGridViewRow.Paint(Graphics graphics, Rectangle clipBounds, Rectangle rowBounds, Int32 rowIndex, DataGridViewElementStates rowState, Boolean isFirstDisplayedRow, Boolean isLastVisibleRow)
   at System.Windows.Forms.DataGridView.PaintRows(Graphics g, Rectangle boundingRect, Rectangle clipRect, Boolean singleHorizontalBorderAdded)
   at System.Windows.Forms.DataGridView.PaintGrid(Graphics g, Rectangle gridBounds, Rectangle clipRect, Boolean singleVerticalBorderAdded, Boolean singleHorizontalBorderAdded)
   at System.Windows.Forms.DataGridView.OnPaint(PaintEventArgs e)
   at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer, Boolean disposeEventArgs)
   at System.Windows.Forms.Control.WmPaint(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.DataGridView.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)


************** Loaded Assemblies **************
mscorlib
    Assembly Version: 2.0.0.0
    Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
    CodeBase: file:///C:/WINDOWS/Microsoft.NET/Framework/v2.0.50727/mscorlib.dll
----------------------------------------
Microsoft.VisualStudio.CommonIDE
    Assembly Version: 9.0.0.0
    Win32 Version: 9.0.30729.1
    CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/Microsoft.VisualStudio.CommonIDE/9.0.0.0__b03f5f7f11d50a3a/Microsoft.VisualStudio.CommonIDE.dll
----------------------------------------
System.Windows.Forms
    Assembly Version: 2.0.0.0
    Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
    CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Windows.Forms/2.0.0.0__b77a5c561934e089/System.Windows.Forms.dll
----------------------------------------
System
    Assembly Version: 2.0.0.0
    Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
    CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System/2.0.0.0__b77a5c561934e089/System.dll
----------------------------------------
System.Drawing
    Assembly Version: 2.0.0.0
    Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
    CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Drawing/2.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
----------------------------------------
System.Configuration
    Assembly Version: 2.0.0.0
    Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
    CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Configuration/2.0.0.0__b03f5f7f11d50a3a/System.Configuration.dll
----------------------------------------
System.Xml
    Assembly Version: 2.0.0.0
    Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
    CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Xml/2.0.0.0__b77a5c561934e089/System.Xml.dll
----------------------------------------
Microsoft.VisualStudio.DebuggerVisualizers
    Assembly Version: 9.0.0.0
    Win32 Version: 9.0.30729.1
    CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/Microsoft.VisualStudio.DebuggerVisualizers/9.0.0.0__b03f5f7f11d50a3a/Microsoft.VisualStudio.DebuggerVisualizers.dll
----------------------------------------
Microsoft.VisualStudio.Debugger.DataSetVisualizer
    Assembly Version: 9.0.0.0
    Win32 Version: 9.0.30729.1
    CodeBase: file:///C:/Program%20Files/Microsoft%20Visual%20Studio%209.0/Common7/Packages/Debugger/Visualizers/Microsoft.VisualStudio.Debugger.DataSetVisualizer.dll
----------------------------------------
System.Data
    Assembly Version: 2.0.0.0
    Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
    CodeBase: file:///C:/WINDOWS/assembly/GAC_32/System.Data/2.0.0.0__b77a5c561934e089/System.Data.dll
----------------------------------------

************** JIT Debugging **************
To enable just-in-time (JIT) debugging, the .config file for this
application or computer (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging
enabled.

For example:

<configuration>
    <system.windows.forms jitDebugging="true" />
</configuration>

When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.

谁能告诉我为什么我会看到这个？但是第二次，当我刷新我的 aspx 页面时，我得到了所有包含正确数据的正确表格。

提前致谢

新编辑

大家好，感谢您的快速回复。但我没有在 catch 中收到任何错误。数据集完全成功填充，即使我得到正确的第一个表的数据，但我发现 2 个表的其余部分没有代码异常。

最新更新

另外我在另一个测试中发现，Dataset Visualizer 没有显示那个数据表节点。它包含记录/表格但仍然显示上述错误。可能是由于某些问题

Answer 1

您是否正在检查返回值是否不为空？您的函数中可能存在一些异常。我会重新制作 catch 部分以

    catch
    {
        return new DataSet();
    }

或者更好的是，我会创建一些错误事件来显示一些错误的消息框。

    catch(Exception exc)
    {
        Error(exc);
        return new DataSet();
    }