Newbie -- what are these errors -- System.NullReferenceException

I am new to .NET and C#. I am deploying the SPS web part that appears below
and I am getting System.NullReferenceException in my CreateChildControls
method. The last item shown by my debugger prior to the exception is
"Setting ID."
Any assistance would be greatly appreciated.
Joe Mack
CODE
--
using System;
using System.ComponentModel;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml.Serialization;
using System.Runtime.InteropServices;
using System.Diagnostics;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.WebPartPages;
using Microsoft.SharePoint.WebPartPages.Communication;
using System.Data;
namespace adSearch
{
/// <summary>
/// Description for WebPart1.
/// </summary>
[DefaultProperty("Text"),
ToolboxData("<{0}:adSearchWP runat=server></{0}:adSearchWP>"),
XmlRoot(Namespace="adSearch")]
public class adSearchWP : Microsoft.SharePoint.WebPartPages.WebPart,
Microsoft.SharePoint.WebPartPages.Communication.IRowProvider
{
public event RowProviderInitEventHandler RowProviderInit;
public event RowReadyEventHandler RowReady;
private bool isConnected = false;
private bool submitClicked = false;
private string[] myFieldNames;
private string[] myFieldDisplayNames;
private DataGrid myDataGrid;
// Create Web Part user interface controls.
protected TextBox searchBox;
protected Button searchButton;
public override void EnsureInterfaces()
{
Debug.Write("Ensuring interfaces.");
RegisterInterface("MGRowProvider", //InterfaceName
InterfaceTypes.IRowProvider, //InterfaceType
WebPart.UnlimitedConnections, //MaxConnections
ConnectionRunAt.Server, //RunAtOptions
this, //InterfaceObject
"",
//InterfaceClientReference
"Provide Data To...", //MenuLabel
"Provides a row of data to a consumer Web Part.", //Description
true);
//allowCrossPageConnection
}
public override ConnectionRunAt CanRunAt()
{
return ConnectionRunAt.Server;
}
public override void PartCommunicationConnect(
string interfaceName,
WebPart connectedPart,
string connectedInterfaceName,
ConnectionRunAt runAt)
{
if (interfaceName == "MGRowProvider")
{
Debug.Write("Connected.");
isConnected = true;
EnsureChildControls();
}
}
public override void PartCommunicationInit()
{
if( isConnected)
{
if (RowProviderInit != null)
{
RowProviderInitEventArgs rowProviderInitArgs = new
RowProviderInitEventArgs();
rowProviderInitArgs.FieldList = myFieldNames;
rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
RowProviderInit(this,rowProviderInitArgs
);
}
}
else
Debug.Write("Need to send something...init");
}
public override void PartCommunicationMain()
{
if (isConnected)
{
if (RowReady != null)
{
RowReadyEventArgs rowReadyArgs = new RowReadyEventArgs();
if (submitClicked)
{
DataRow[] dr = new DataRow[1];
dr[0] = ((DataTable)myDataGrid.DataSource).Rows[0];
rowReadyArgs.Rows = dr;
rowReadyArgs.SelectionStatus = "Standard";
}
RowReady(this,rowReadyArgs);
}
}
else
Debug.Write("Need to send something...main");
}
public override InitEventArgs GetInitEventArgs(string interfaceName)
{
if (interfaceName == "MGRowProvider")
{
EnsureChildControls();
RowProviderInitEventArgs rowProviderInitArgs = new
RowProviderInitEventArgs();
rowProviderInitArgs.FieldList = myFieldNames;
rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
return(rowProviderInitArgs);
}
else
return(null);
}
/// <summary>
/// Render this Web Part to the output parameter specified.
/// </summary>
/// <param name="output"> The HTML writer to write out to </param>
protected override void RenderWebPart(HtmlTextWriter output)
{
EnsureChildControls();
Debug.Write("rendering web part.");
output.RenderBeginTag("div");
// Check if connected.
if(isConnected)
{
Debug.Write("Connected. Rendering web part");
// Line break.
output.RenderBeginTag(HtmlTextWriterTag.Br);
output.RenderEndTag();
output.RenderBeginTag(HtmlTextWriterTag.Table);
output.RenderBeginTag(HtmlTextWriterTag.Tr);
output.RenderBeginTag(HtmlTextWriterTag.Th);
output.Write("Search For:");
output.RenderEndTag();
output.RenderBeginTag("td");
searchBox.RenderControl(output);
output.RenderEndTag();
output.RenderBeginTag("td");
searchButton.RenderControl(output);
output.RenderEndTag();
output.RenderEndTag();
output.RenderEndTag();
}
else
{
Debug.Write("Not connected, writing message.");
// The Web Part isn't connected.
output.Write("Not connected.");
}
output.RenderEndTag();
}
protected override void CreateChildControls()
{
Debug.Write("Creating child controls");
try
{
Debug.Write("Setting ID.");
searchBox.ID = "srchBox";
Debug.Write("Done setting ID. Setting width.");
this.searchBox.Width=Unit.Percentage(100);
Debug.Write("Done setting width. Adding search box.");
this.Controls.Add(searchBox);
Debug.Write("Created Search Box");
}
catch (Exception ex)
{
Debug.Write("Exception - search box: " + ex);
}
try
{
this.searchButton.Text = "Submit";
this.searchButton.Click += new System.EventHandler(searchButton_Click);
this.Controls.Add(searchButton);
Debug.Write("Created Search Button");
}
catch (Exception ex)
{
Debug.Write("Exception - search button: " + ex);
}
}
private void searchButton_Click(object sender, EventArgs e)
{
submitClicked = true; //user clicked button, set to true
Debug.Write("Button clicked.");
DataTable dataTable = new DataTable();
// Add three column objects to the table.
DataColumn anrColumn = new DataColumn();
anrColumn.DataType = System.Type.GetType("System.String");
anrColumn.ColumnName = "anr";
anrColumn.Caption = "ANR";
dataTable.Columns.Add(anrColumn);
DataRow dataRow;
dataRow = dataTable.NewRow();
// Then add the new row to the collection.
dataRow["anr"] = searchBox.Text;
dataTable.Rows.Add(dataRow);
myDataGrid.DataSource = dataTable;
myDataGrid.ID = "DataGrid";
myDataGrid.Attributes.Add("WDFLibID", "ServerSideRowProvider_DataGrid");
myDataGrid.DataBind();
//Set the DataTable FieldName information.
//This information will be passed to the Consumer by
//firing the RowProviderInit event.
int columnCount = dataTable.Columns.Count;
myFieldNames = new string[columnCount];
myFieldDisplayNames = new string[columnCount];
for(int i = 0; i < columnCount; i++)
{
myFieldNames[i] = dataTable.Columns[i].ColumnName;
myFieldDisplayNames[i] = dataTable.Columns[i].Caption;
}
}
}
}System.NullReferenceException iundicates that you are, in your code
somewhere, referencing an object that doesn't exist. For example:
object o;
string s = o.ToString(); // As o is not initialized to anything, you will
get a System.NullReferenceException
HTH,
Kevin Spencer
.Net Developer
Microsoft MVP
Neither a follower
nor a lender be.
"Joe" <Joe@.discussions.microsoft.com> wrote in message
news:F9BD4158-B270-44D2-8572-379F055F4F4C@.microsoft.com...
> I am new to .NET and C#. I am deploying the SPS web part that appears
below
> and I am getting System.NullReferenceException in my CreateChildControls
> method. The last item shown by my debugger prior to the exception is
> "Setting ID."
> Any assistance would be greatly appreciated.
> Joe Mack
> --
> CODE
> --
> using System;
> using System.ComponentModel;
> using System.Web.UI;
> using System.Web.UI.WebControls;
> using System.Xml.Serialization;
> using System.Runtime.InteropServices;
> using System.Diagnostics;
> using Microsoft.SharePoint;
> using Microsoft.SharePoint.Utilities;
> using Microsoft.SharePoint.WebPartPages;
> using Microsoft.SharePoint.WebPartPages.Communication;
> using System.Data;
> namespace adSearch
> {
> /// <summary>
> /// Description for WebPart1.
> /// </summary>
> [DefaultProperty("Text"),
> ToolboxData("<{0}:adSearchWP runat=server></{0}:adSearchWP>"),
> XmlRoot(Namespace="adSearch")]
> public class adSearchWP : Microsoft.SharePoint.WebPartPages.WebPart,
> Microsoft.SharePoint.WebPartPages.Communication.IRowProvider
> {
> public event RowProviderInitEventHandler RowProviderInit;
> public event RowReadyEventHandler RowReady;
> private bool isConnected = false;
> private bool submitClicked = false;
> private string[] myFieldNames;
> private string[] myFieldDisplayNames;
> private DataGrid myDataGrid;
>
> // Create Web Part user interface controls.
> protected TextBox searchBox;
> protected Button searchButton;
> public override void EnsureInterfaces()
> {
> Debug.Write("Ensuring interfaces.");
> RegisterInterface("MGRowProvider", //InterfaceName
> InterfaceTypes.IRowProvider, //InterfaceType
> WebPart.UnlimitedConnections, //MaxConnections
> ConnectionRunAt.Server, //RunAtOptions
> this, //InterfaceObject
> "",
> //InterfaceClientReference
> "Provide Data To...", //MenuLabel
> "Provides a row of data to a consumer Web Part.", //Description
> true);
> //allowCrossPageConnection
> }
> public override ConnectionRunAt CanRunAt()
> {
> return ConnectionRunAt.Server;
> }
> public override void PartCommunicationConnect(
> string interfaceName,
> WebPart connectedPart,
> string connectedInterfaceName,
> ConnectionRunAt runAt)
> {
> if (interfaceName == "MGRowProvider")
> {
> Debug.Write("Connected.");
> isConnected = true;
> EnsureChildControls();
> }
> }
> public override void PartCommunicationInit()
> {
> if( isConnected)
> {
> if (RowProviderInit != null)
> {
> RowProviderInitEventArgs rowProviderInitArgs = new
> RowProviderInitEventArgs();
> rowProviderInitArgs.FieldList = myFieldNames;
> rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
> RowProviderInit(this,rowProviderInitArgs
);
> }
> }
> else
> Debug.Write("Need to send something...init");
> }
> public override void PartCommunicationMain()
> {
> if (isConnected)
> {
> if (RowReady != null)
> {
> RowReadyEventArgs rowReadyArgs = new RowReadyEventArgs();
> if (submitClicked)
> {
> DataRow[] dr = new DataRow[1];
> dr[0] = ((DataTable)myDataGrid.DataSource).Rows[0];
> rowReadyArgs.Rows = dr;
> rowReadyArgs.SelectionStatus = "Standard";
> }
> RowReady(this,rowReadyArgs);
> }
> }
> else
> Debug.Write("Need to send something...main");
> }
> public override InitEventArgs GetInitEventArgs(string interfaceName)
> {
> if (interfaceName == "MGRowProvider")
> {
> EnsureChildControls();
> RowProviderInitEventArgs rowProviderInitArgs = new
> RowProviderInitEventArgs();
> rowProviderInitArgs.FieldList = myFieldNames;
> rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
> return(rowProviderInitArgs);
> }
> else
> return(null);
> }
> /// <summary>
> /// Render this Web Part to the output parameter specified.
> /// </summary>
> /// <param name="output"> The HTML writer to write out to </param>
> protected override void RenderWebPart(HtmlTextWriter output)
> {
> EnsureChildControls();
> Debug.Write("rendering web part.");
> output.RenderBeginTag("div");
> // Check if connected.
> if(isConnected)
> {
> Debug.Write("Connected. Rendering web part");
> // Line break.
> output.RenderBeginTag(HtmlTextWriterTag.Br);
> output.RenderEndTag();
> output.RenderBeginTag(HtmlTextWriterTag.Table);
> output.RenderBeginTag(HtmlTextWriterTag.Tr);
> output.RenderBeginTag(HtmlTextWriterTag.Th);
> output.Write("Search For:");
> output.RenderEndTag();
> output.RenderBeginTag("td");
> searchBox.RenderControl(output);
> output.RenderEndTag();
> output.RenderBeginTag("td");
> searchButton.RenderControl(output);
> output.RenderEndTag();
> output.RenderEndTag();
> output.RenderEndTag();
> }
> else
> {
> Debug.Write("Not connected, writing message.");
> // The Web Part isn't connected.
> output.Write("Not connected.");
> }
> output.RenderEndTag();
> }
> protected override void CreateChildControls()
> {
> Debug.Write("Creating child controls");
> try
> {
> Debug.Write("Setting ID.");
> searchBox.ID = "srchBox";
> Debug.Write("Done setting ID. Setting width.");
> this.searchBox.Width=Unit.Percentage(100);
> Debug.Write("Done setting width. Adding search box.");
> this.Controls.Add(searchBox);
> Debug.Write("Created Search Box");
> }
> catch (Exception ex)
> {
> Debug.Write("Exception - search box: " + ex);
> }
> try
> {
> this.searchButton.Text = "Submit";
> this.searchButton.Click += new System.EventHandler(searchButton_Click);
> this.Controls.Add(searchButton);
> Debug.Write("Created Search Button");
> }
> catch (Exception ex)
> {
> Debug.Write("Exception - search button: " + ex);
> }
> }
> private void searchButton_Click(object sender, EventArgs e)
> {
> submitClicked = true; //user clicked button, set to true
> Debug.Write("Button clicked.");
> DataTable dataTable = new DataTable();
> // Add three column objects to the table.
> DataColumn anrColumn = new DataColumn();
> anrColumn.DataType = System.Type.GetType("System.String");
> anrColumn.ColumnName = "anr";
> anrColumn.Caption = "ANR";
> dataTable.Columns.Add(anrColumn);
> DataRow dataRow;
> dataRow = dataTable.NewRow();
> // Then add the new row to the collection.
> dataRow["anr"] = searchBox.Text;
> dataTable.Rows.Add(dataRow);
> myDataGrid.DataSource = dataTable;
> myDataGrid.ID = "DataGrid";
> myDataGrid.Attributes.Add("WDFLibID", "ServerSideRowProvider_DataGrid");
> myDataGrid.DataBind();
> //Set the DataTable FieldName information.
> //This information will be passed to the Consumer by
> //firing the RowProviderInit event.
> int columnCount = dataTable.Columns.Count;
> myFieldNames = new string[columnCount];
> myFieldDisplayNames = new string[columnCount];
> for(int i = 0; i < columnCount; i++)
> {
> myFieldNames[i] = dataTable.Columns[i].ColumnName;
> myFieldDisplayNames[i] = dataTable.Columns[i].Caption;
> }
> }
> }
> }
>
>
On Tue, 9 Nov 2004 10:53:03 -0800, Joe <Joe@.discussions.microsoft.com>
wrote:

>I am new to .NET and C#. I am deploying the SPS web part that appears belo
w
>and I am getting System.NullReferenceException in my CreateChildControls
>method. The last item shown by my debugger prior to the exception is
>"Setting ID."
>Any assistance would be greatly appreciated.
>Joe Mack
> <SNIP CODE>
You are not instantiating search Box before assigning the .ID in this
line:
searchBox.ID = "srchBox";
You need to instantiate the control like so:
searchBox = new TextBox();
This also goes for any other controls you use as well.
Thanks,
Chris Simmons
newsgroup.replies@.netchris.com

Newbie -- what are these errors -- System.NullReferenceException

I am new to .NET and C#. I am deploying the SPS web part that appears below
and I am getting System.NullReferenceException in my CreateChildControls
method. The last item shown by my debugger prior to the exception is
"Setting ID."

Any assistance would be greatly appreciated.

Joe Mack

-----
CODE
-----
using System;
using System.ComponentModel;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml.Serialization;
using System.Runtime.InteropServices;
using System.Diagnostics;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.WebPartPages;
using Microsoft.SharePoint.WebPartPages.Communication;
using System.Data;

namespace adSearch
{
/// <summary>
/// Description for WebPart1.
/// </summary>
[DefaultProperty("Text"),
ToolboxData("<{0}:adSearchWP runat=server></{0}:adSearchWP>"),
XmlRoot(Namespace="adSearch")]
public class adSearchWP : Microsoft.SharePoint.WebPartPages.WebPart,
Microsoft.SharePoint.WebPartPages.Communication.IR owProvider
{
public event RowProviderInitEventHandler RowProviderInit;
public event RowReadyEventHandler RowReady;

private bool isConnected = false;
private bool submitClicked = false;

private string[] myFieldNames;
private string[] myFieldDisplayNames;

private DataGrid myDataGrid;

// Create Web Part user interface controls.
protected TextBox searchBox;
protected Button searchButton;

public override void EnsureInterfaces()
{
Debug.Write("Ensuring interfaces.");
RegisterInterface("MGRowProvider", //InterfaceName
InterfaceTypes.IRowProvider, //InterfaceType
WebPart.UnlimitedConnections, //MaxConnections
ConnectionRunAt.Server, //RunAtOptions
this, //InterfaceObject
"",
//InterfaceClientReference
"Provide Data To...", //MenuLabel
"Provides a row of data to a consumer Web Part.", //Description
true);
//allowCrossPageConnection
}

public override ConnectionRunAt CanRunAt()
{
return ConnectionRunAt.Server;
}

public override void PartCommunicationConnect(
string interfaceName,
WebPart connectedPart,
string connectedInterfaceName,
ConnectionRunAt runAt)
{
if (interfaceName == "MGRowProvider")
{
Debug.Write("Connected.");
isConnected = true;
EnsureChildControls();
}
}

public override void PartCommunicationInit()
{
if( isConnected)
{
if (RowProviderInit != null)
{
RowProviderInitEventArgs rowProviderInitArgs = new
RowProviderInitEventArgs();
rowProviderInitArgs.FieldList = myFieldNames;
rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
RowProviderInit(this,rowProviderInitArgs);
}
}
else
Debug.Write("Need to send something...init");
}

public override void PartCommunicationMain()
{
if (isConnected)
{
if (RowReady != null)
{
RowReadyEventArgs rowReadyArgs = new RowReadyEventArgs();

if (submitClicked)
{
DataRow[] dr = new DataRow[1];
dr[0] = ((DataTable)myDataGrid.DataSource).Rows[0];
rowReadyArgs.Rows = dr;
rowReadyArgs.SelectionStatus = "Standard";
}
RowReady(this,rowReadyArgs);
}
}
else
Debug.Write("Need to send something...main");
}

public override InitEventArgs GetInitEventArgs(string interfaceName)
{
if (interfaceName == "MGRowProvider")
{
EnsureChildControls();
RowProviderInitEventArgs rowProviderInitArgs = new
RowProviderInitEventArgs();
rowProviderInitArgs.FieldList = myFieldNames;
rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
return(rowProviderInitArgs);
}
else
return(null);
}

/// <summary>
/// Render this Web Part to the output parameter specified.
/// </summary>
/// <param name="output"> The HTML writer to write out to </param>
protected override void RenderWebPart(HtmlTextWriter output)
{
EnsureChildControls();
Debug.Write("rendering web part.");
output.RenderBeginTag("div");

// Check if connected.
if(isConnected)
{
Debug.Write("Connected. Rendering web part");
// Line break.
output.RenderBeginTag(HtmlTextWriterTag.Br);
output.RenderEndTag();

output.RenderBeginTag(HtmlTextWriterTag.Table);
output.RenderBeginTag(HtmlTextWriterTag.Tr);
output.RenderBeginTag(HtmlTextWriterTag.Th);
output.Write("Search For:");
output.RenderEndTag();
output.RenderBeginTag("td");
searchBox.RenderControl(output);
output.RenderEndTag();
output.RenderBeginTag("td");
searchButton.RenderControl(output);
output.RenderEndTag();
output.RenderEndTag();
output.RenderEndTag();

}
else
{
Debug.Write("Not connected, writing message.");
// The Web Part isn't connected.
output.Write("Not connected.");
}
output.RenderEndTag();
}
protected override void CreateChildControls()
{
Debug.Write("Creating child controls");
try
{
Debug.Write("Setting ID.");
searchBox.ID = "srchBox";
Debug.Write("Done setting ID. Setting width.");
this.searchBox.Width=Unit.Percentage(100);
Debug.Write("Done setting width. Adding search box.");
this.Controls.Add(searchBox);
Debug.Write("Created Search Box");
}
catch (Exception ex)
{
Debug.Write("Exception - search box: " + ex);
}

try
{
this.searchButton.Text = "Submit";
this.searchButton.Click += new System.EventHandler(searchButton_Click);
this.Controls.Add(searchButton);
Debug.Write("Created Search Button");
}
catch (Exception ex)
{
Debug.Write("Exception - search button: " + ex);
}

}

private void searchButton_Click(object sender, EventArgs e)
{
submitClicked = true; //user clicked button, set to true
Debug.Write("Button clicked.");
DataTable dataTable = new DataTable();
// Add three column objects to the table.
DataColumn anrColumn = new DataColumn();
anrColumn.DataType = System.Type.GetType("System.String");
anrColumn.ColumnName = "anr";
anrColumn.Caption = "ANR";
dataTable.Columns.Add(anrColumn);
DataRow dataRow;
dataRow = dataTable.NewRow();
// Then add the new row to the collection.
dataRow["anr"] = searchBox.Text;
dataTable.Rows.Add(dataRow);

myDataGrid.DataSource = dataTable;
myDataGrid.ID = "DataGrid";
myDataGrid.Attributes.Add("WDFLibID", "ServerSideRowProvider_DataGrid");
myDataGrid.DataBind();

//Set the DataTable FieldName information.
//This information will be passed to the Consumer by
//firing the RowProviderInit event.
int columnCount = dataTable.Columns.Count;
myFieldNames = new string[columnCount];
myFieldDisplayNames = new string[columnCount];

for(int i = 0; i < columnCount; i++)
{
myFieldNames[i] = dataTable.Columns[i].ColumnName;
myFieldDisplayNames[i] = dataTable.Columns[i].Caption;
}
}

}
}System.NullReferenceException iundicates that you are, in your code
somewhere, referencing an object that doesn't exist. For example:

object o;

string s = o.ToString(); // As o is not initialized to anything, you will
get a System.NullReferenceException

--
HTH,
Kevin Spencer
..Net Developer
Microsoft MVP
Neither a follower
nor a lender be.

"Joe" <Joe@.discussions.microsoft.com> wrote in message
news:F9BD4158-B270-44D2-8572-379F055F4F4C@.microsoft.com...
> I am new to .NET and C#. I am deploying the SPS web part that appears
below
> and I am getting System.NullReferenceException in my CreateChildControls
> method. The last item shown by my debugger prior to the exception is
> "Setting ID."
> Any assistance would be greatly appreciated.
> Joe Mack
> -----
> CODE
> -----
> using System;
> using System.ComponentModel;
> using System.Web.UI;
> using System.Web.UI.WebControls;
> using System.Xml.Serialization;
> using System.Runtime.InteropServices;
> using System.Diagnostics;
> using Microsoft.SharePoint;
> using Microsoft.SharePoint.Utilities;
> using Microsoft.SharePoint.WebPartPages;
> using Microsoft.SharePoint.WebPartPages.Communication;
> using System.Data;
> namespace adSearch
> {
> /// <summary>
> /// Description for WebPart1.
> /// </summary>
> [DefaultProperty("Text"),
> ToolboxData("<{0}:adSearchWP runat=server></{0}:adSearchWP>"),
> XmlRoot(Namespace="adSearch")]
> public class adSearchWP : Microsoft.SharePoint.WebPartPages.WebPart,
> Microsoft.SharePoint.WebPartPages.Communication.IR owProvider
> {
> public event RowProviderInitEventHandler RowProviderInit;
> public event RowReadyEventHandler RowReady;
> private bool isConnected = false;
> private bool submitClicked = false;
> private string[] myFieldNames;
> private string[] myFieldDisplayNames;
> private DataGrid myDataGrid;
>
> // Create Web Part user interface controls.
> protected TextBox searchBox;
> protected Button searchButton;
> public override void EnsureInterfaces()
> {
> Debug.Write("Ensuring interfaces.");
> RegisterInterface("MGRowProvider", //InterfaceName
> InterfaceTypes.IRowProvider, //InterfaceType
> WebPart.UnlimitedConnections, //MaxConnections
> ConnectionRunAt.Server, //RunAtOptions
> this, //InterfaceObject
> "",
> //InterfaceClientReference
> "Provide Data To...", //MenuLabel
> "Provides a row of data to a consumer Web Part.", //Description
> true);
> //allowCrossPageConnection
> }
> public override ConnectionRunAt CanRunAt()
> {
> return ConnectionRunAt.Server;
> }
> public override void PartCommunicationConnect(
> string interfaceName,
> WebPart connectedPart,
> string connectedInterfaceName,
> ConnectionRunAt runAt)
> {
> if (interfaceName == "MGRowProvider")
> {
> Debug.Write("Connected.");
> isConnected = true;
> EnsureChildControls();
> }
> }
> public override void PartCommunicationInit()
> {
> if( isConnected)
> {
> if (RowProviderInit != null)
> {
> RowProviderInitEventArgs rowProviderInitArgs = new
> RowProviderInitEventArgs();
> rowProviderInitArgs.FieldList = myFieldNames;
> rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
> RowProviderInit(this,rowProviderInitArgs);
> }
> }
> else
> Debug.Write("Need to send something...init");
> }
> public override void PartCommunicationMain()
> {
> if (isConnected)
> {
> if (RowReady != null)
> {
> RowReadyEventArgs rowReadyArgs = new RowReadyEventArgs();
> if (submitClicked)
> {
> DataRow[] dr = new DataRow[1];
> dr[0] = ((DataTable)myDataGrid.DataSource).Rows[0];
> rowReadyArgs.Rows = dr;
> rowReadyArgs.SelectionStatus = "Standard";
> }
> RowReady(this,rowReadyArgs);
> }
> }
> else
> Debug.Write("Need to send something...main");
> }
> public override InitEventArgs GetInitEventArgs(string interfaceName)
> {
> if (interfaceName == "MGRowProvider")
> {
> EnsureChildControls();
> RowProviderInitEventArgs rowProviderInitArgs = new
> RowProviderInitEventArgs();
> rowProviderInitArgs.FieldList = myFieldNames;
> rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
> return(rowProviderInitArgs);
> }
> else
> return(null);
> }
> /// <summary>
> /// Render this Web Part to the output parameter specified.
> /// </summary>
> /// <param name="output"> The HTML writer to write out to </param>
> protected override void RenderWebPart(HtmlTextWriter output)
> {
> EnsureChildControls();
> Debug.Write("rendering web part.");
> output.RenderBeginTag("div");
> // Check if connected.
> if(isConnected)
> {
> Debug.Write("Connected. Rendering web part");
> // Line break.
> output.RenderBeginTag(HtmlTextWriterTag.Br);
> output.RenderEndTag();
> output.RenderBeginTag(HtmlTextWriterTag.Table);
> output.RenderBeginTag(HtmlTextWriterTag.Tr);
> output.RenderBeginTag(HtmlTextWriterTag.Th);
> output.Write("Search For:");
> output.RenderEndTag();
> output.RenderBeginTag("td");
> searchBox.RenderControl(output);
> output.RenderEndTag();
> output.RenderBeginTag("td");
> searchButton.RenderControl(output);
> output.RenderEndTag();
> output.RenderEndTag();
> output.RenderEndTag();
> }
> else
> {
> Debug.Write("Not connected, writing message.");
> // The Web Part isn't connected.
> output.Write("Not connected.");
> }
> output.RenderEndTag();
> }
> protected override void CreateChildControls()
> {
> Debug.Write("Creating child controls");
> try
> {
> Debug.Write("Setting ID.");
> searchBox.ID = "srchBox";
> Debug.Write("Done setting ID. Setting width.");
> this.searchBox.Width=Unit.Percentage(100);
> Debug.Write("Done setting width. Adding search box.");
> this.Controls.Add(searchBox);
> Debug.Write("Created Search Box");
> }
> catch (Exception ex)
> {
> Debug.Write("Exception - search box: " + ex);
> }
> try
> {
> this.searchButton.Text = "Submit";
> this.searchButton.Click += new System.EventHandler(searchButton_Click);
> this.Controls.Add(searchButton);
> Debug.Write("Created Search Button");
> }
> catch (Exception ex)
> {
> Debug.Write("Exception - search button: " + ex);
> }
> }
> private void searchButton_Click(object sender, EventArgs e)
> {
> submitClicked = true; //user clicked button, set to true
> Debug.Write("Button clicked.");
> DataTable dataTable = new DataTable();
> // Add three column objects to the table.
> DataColumn anrColumn = new DataColumn();
> anrColumn.DataType = System.Type.GetType("System.String");
> anrColumn.ColumnName = "anr";
> anrColumn.Caption = "ANR";
> dataTable.Columns.Add(anrColumn);
> DataRow dataRow;
> dataRow = dataTable.NewRow();
> // Then add the new row to the collection.
> dataRow["anr"] = searchBox.Text;
> dataTable.Rows.Add(dataRow);
> myDataGrid.DataSource = dataTable;
> myDataGrid.ID = "DataGrid";
> myDataGrid.Attributes.Add("WDFLibID", "ServerSideRowProvider_DataGrid");
> myDataGrid.DataBind();
> //Set the DataTable FieldName information.
> //This information will be passed to the Consumer by
> //firing the RowProviderInit event.
> int columnCount = dataTable.Columns.Count;
> myFieldNames = new string[columnCount];
> myFieldDisplayNames = new string[columnCount];
> for(int i = 0; i < columnCount; i++)
> {
> myFieldNames[i] = dataTable.Columns[i].ColumnName;
> myFieldDisplayNames[i] = dataTable.Columns[i].Caption;
> }
> }
> }
> }
Kevin:

Thanks.

I was failing to instantiate my objects in the CreateChildControls method.
All I did was add two lines: "searchBox = new TextBox();" and
"searchButton = new Button();"

Joe

"Kevin Spencer" wrote:

> System.NullReferenceException iundicates that you are, in your code
> somewhere, referencing an object that doesn't exist. For example:
> object o;
> string s = o.ToString(); // As o is not initialized to anything, you will
> get a System.NullReferenceException
> --
> HTH,
> Kevin Spencer
> ..Net Developer
> Microsoft MVP
> Neither a follower
> nor a lender be.
> "Joe" <Joe@.discussions.microsoft.com> wrote in message
> news:F9BD4158-B270-44D2-8572-379F055F4F4C@.microsoft.com...
> > I am new to .NET and C#. I am deploying the SPS web part that appears
> below
> > and I am getting System.NullReferenceException in my CreateChildControls
> > method. The last item shown by my debugger prior to the exception is
> > "Setting ID."
> > Any assistance would be greatly appreciated.
> > Joe Mack
> > -----
> > CODE
> > -----
> > using System;
> > using System.ComponentModel;
> > using System.Web.UI;
> > using System.Web.UI.WebControls;
> > using System.Xml.Serialization;
> > using System.Runtime.InteropServices;
> > using System.Diagnostics;
> > using Microsoft.SharePoint;
> > using Microsoft.SharePoint.Utilities;
> > using Microsoft.SharePoint.WebPartPages;
> > using Microsoft.SharePoint.WebPartPages.Communication;
> > using System.Data;
> > namespace adSearch
> > {
> > /// <summary>
> > /// Description for WebPart1.
> > /// </summary>
> > [DefaultProperty("Text"),
> > ToolboxData("<{0}:adSearchWP runat=server></{0}:adSearchWP>"),
> > XmlRoot(Namespace="adSearch")]
> > public class adSearchWP : Microsoft.SharePoint.WebPartPages.WebPart,
> > Microsoft.SharePoint.WebPartPages.Communication.IR owProvider
> > {
> > public event RowProviderInitEventHandler RowProviderInit;
> > public event RowReadyEventHandler RowReady;
> > private bool isConnected = false;
> > private bool submitClicked = false;
> > private string[] myFieldNames;
> > private string[] myFieldDisplayNames;
> > private DataGrid myDataGrid;
> > // Create Web Part user interface controls.
> > protected TextBox searchBox;
> > protected Button searchButton;
> > public override void EnsureInterfaces()
> > {
> > Debug.Write("Ensuring interfaces.");
> > RegisterInterface("MGRowProvider", //InterfaceName
> > InterfaceTypes.IRowProvider, //InterfaceType
> > WebPart.UnlimitedConnections, //MaxConnections
> > ConnectionRunAt.Server, //RunAtOptions
> > this, //InterfaceObject
> > "",
> > //InterfaceClientReference
> > "Provide Data To...", //MenuLabel
> > "Provides a row of data to a consumer Web Part.", //Description
> > true);
> > //allowCrossPageConnection
> > }
> > public override ConnectionRunAt CanRunAt()
> > {
> > return ConnectionRunAt.Server;
> > }
> > public override void PartCommunicationConnect(
> > string interfaceName,
> > WebPart connectedPart,
> > string connectedInterfaceName,
> > ConnectionRunAt runAt)
> > {
> > if (interfaceName == "MGRowProvider")
> > {
> > Debug.Write("Connected.");
> > isConnected = true;
> > EnsureChildControls();
> > }
> > }
> > public override void PartCommunicationInit()
> > {
> > if( isConnected)
> > {
> > if (RowProviderInit != null)
> > {
> > RowProviderInitEventArgs rowProviderInitArgs = new
> > RowProviderInitEventArgs();
> > rowProviderInitArgs.FieldList = myFieldNames;
> > rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
> > RowProviderInit(this,rowProviderInitArgs);
> > }
> > }
> > else
> > Debug.Write("Need to send something...init");
> > }
> > public override void PartCommunicationMain()
> > {
> > if (isConnected)
> > {
> > if (RowReady != null)
> > {
> > RowReadyEventArgs rowReadyArgs = new RowReadyEventArgs();
> > if (submitClicked)
> > {
> > DataRow[] dr = new DataRow[1];
> > dr[0] = ((DataTable)myDataGrid.DataSource).Rows[0];
> > rowReadyArgs.Rows = dr;
> > rowReadyArgs.SelectionStatus = "Standard";
> > }
> > RowReady(this,rowReadyArgs);
> > }
> > }
> > else
> > Debug.Write("Need to send something...main");
> > }
> > public override InitEventArgs GetInitEventArgs(string interfaceName)
> > {
> > if (interfaceName == "MGRowProvider")
> > {
> > EnsureChildControls();
> > RowProviderInitEventArgs rowProviderInitArgs = new
> > RowProviderInitEventArgs();
> > rowProviderInitArgs.FieldList = myFieldNames;
> > rowProviderInitArgs.FieldDisplayList = myFieldDisplayNames;
> > return(rowProviderInitArgs);
> > }
> > else
> > return(null);
> > }
> > /// <summary>
> > /// Render this Web Part to the output parameter specified.
> > /// </summary>
> > /// <param name="output"> The HTML writer to write out to </param>
> > protected override void RenderWebPart(HtmlTextWriter output)
> > {
> > EnsureChildControls();
> > Debug.Write("rendering web part.");
> > output.RenderBeginTag("div");
> > // Check if connected.
> > if(isConnected)
> > {
> > Debug.Write("Connected. Rendering web part");
> > // Line break.
> > output.RenderBeginTag(HtmlTextWriterTag.Br);
> > output.RenderEndTag();
> > output.RenderBeginTag(HtmlTextWriterTag.Table);
> > output.RenderBeginTag(HtmlTextWriterTag.Tr);
> > output.RenderBeginTag(HtmlTextWriterTag.Th);
> > output.Write("Search For:");
> > output.RenderEndTag();
> > output.RenderBeginTag("td");
> > searchBox.RenderControl(output);
> > output.RenderEndTag();
> > output.RenderBeginTag("td");
> > searchButton.RenderControl(output);
> > output.RenderEndTag();
> > output.RenderEndTag();
> > output.RenderEndTag();
> > }
> > else
> > {
> > Debug.Write("Not connected, writing message.");
> > // The Web Part isn't connected.
> > output.Write("Not connected.");
> > }
> > output.RenderEndTag();
> > }
> > protected override void CreateChildControls()
> > {
> > Debug.Write("Creating child controls");
> > try
> > {
> > Debug.Write("Setting ID.");
> > searchBox.ID = "srchBox";
> > Debug.Write("Done setting ID. Setting width.");
> > this.searchBox.Width=Unit.Percentage(100);
> > Debug.Write("Done setting width. Adding search box.");
> > this.Controls.Add(searchBox);
> > Debug.Write("Created Search Box");
> > }
> > catch (Exception ex)
> > {
> > Debug.Write("Exception - search box: " + ex);
> > }
> > try
> > {
> > this.searchButton.Text = "Submit";
> > this.searchButton.Click += new System.EventHandler(searchButton_Click);
> > this.Controls.Add(searchButton);
> > Debug.Write("Created Search Button");
> > }
> > catch (Exception ex)
> > {
> > Debug.Write("Exception - search button: " + ex);
> > }
> > }
> > private void searchButton_Click(object sender, EventArgs e)
> > {
> > submitClicked = true; //user clicked button, set to true
> > Debug.Write("Button clicked.");
> > DataTable dataTable = new DataTable();
> > // Add three column objects to the table.
> > DataColumn anrColumn = new DataColumn();
> > anrColumn.DataType = System.Type.GetType("System.String");
> > anrColumn.ColumnName = "anr";
> > anrColumn.Caption = "ANR";
> > dataTable.Columns.Add(anrColumn);
> > DataRow dataRow;
> > dataRow = dataTable.NewRow();
> > // Then add the new row to the collection.
> > dataRow["anr"] = searchBox.Text;
> > dataTable.Rows.Add(dataRow);
> > myDataGrid.DataSource = dataTable;
> > myDataGrid.ID = "DataGrid";
> > myDataGrid.Attributes.Add("WDFLibID", "ServerSideRowProvider_DataGrid");
> > myDataGrid.DataBind();
> > //Set the DataTable FieldName information.
> > //This information will be passed to the Consumer by
> > //firing the RowProviderInit event.
> > int columnCount = dataTable.Columns.Count;
> > myFieldNames = new string[columnCount];
> > myFieldDisplayNames = new string[columnCount];
> > for(int i = 0; i < columnCount; i++)
> > {
> > myFieldNames[i] = dataTable.Columns[i].ColumnName;
> > myFieldDisplayNames[i] = dataTable.Columns[i].Caption;
> > }
> > }
> > }
> > }
>
On Tue, 9 Nov 2004 10:53:03 -0800, Joe <Joe@.discussions.microsoft.com>
wrote:

>I am new to .NET and C#. I am deploying the SPS web part that appears below
>and I am getting System.NullReferenceException in my CreateChildControls
>method. The last item shown by my debugger prior to the exception is
>"Setting ID."
>Any assistance would be greatly appreciated.
>Joe Mack
> <SNIP CODE
You are not instantiating search Box before assigning the .ID in this
line:
searchBox.ID = "srchBox";

You need to instantiate the control like so:
searchBox = new TextBox();

This also goes for any other controls you use as well.

--
Thanks,
Chris Simmons
newsgroup.replies@.netchris.com

Newbie confusion?

Friends, I am a very seasoned developer, but very new to ASP.NET.
Occasionally I get errors displayed in the browser while visiting my ASP.NET
site:
Compiler Error Message: CS0433: The type 'RSWEBNET.InventoryGrid' exists in
both 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET
Files\rswebnet\420cd3b1\409a151c\App_Web
_inventorygrid.aspx.cdcab7d2.x0wll1w
6.dll'
and 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET
Files\rswebnet\420cd3b1\409a151c\assembl
y\dl3\0d390d9e\09072fd1_062dc601\RSW
ebNET.DLL'
Anyway, there is a conflict between to DLLs, I guess. Of course, I didn't
put these DLLs into these places. I'm sure I can fix this and move on by
simply deleting a directory or two. But my questions...
Why do these directories exist when the "real" DLLs live under
C:\Inetpub\wwwroot\RSWebNET?
Are the mechanisms that are supped eliminate DLL-hell actually creating a
new DLL-hell on my behalf?
Am I missing some fundamental clues, and if so, can you refer me to an
informative link or two?
I sincerely appreciate any time you spend reading and responding to this. I
hope I can help you folks at some point in the future. Thanks in advance
for your time and words!
James Hunter RossI'm not positive where you are getting the duplicate definition's from,
but to answer your other question, those DLL's are being created under
those temporary directories so that ASP.NET can lock the files for use
for the web server, but allowing you to edit the application at the
same time. It's basically shadow copies.
As for your your other problem, it looks like you are defining a class
InventoryGrid in inventorygrid.aspx, and using a reference to
RSWebNET.DLL which defines InventoryGrid as well, but it's hard to
tell.
Darren Kopp
http://blog.secudocs.com/

Newbie confusion?

Friends, I am a very seasoned developer, but very new to ASP.NET.
Occasionally I get errors displayed in the browser while visiting my ASP.NET
site:

Compiler Error Message: CS0433: The type 'RSWEBNET.InventoryGrid' exists in
both 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Tem porary ASP.NET
Files\rswebnet\420cd3b1\409a151c\App_Web_inventory grid.aspx.cdcab7d2.x0wll1w6.dll'
and 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Tem porary ASP.NET
Files\rswebnet\420cd3b1\409a151c\assembly\dl3\0d39 0d9e\09072fd1_062dc601\RSWebNET.DLL'

Anyway, there is a conflict between to DLLs, I guess. Of course, I didn't
put these DLLs into these places. I'm sure I can fix this and move on by
simply deleting a directory or two. But my questions...

Why do these directories exist when the "real" DLLs live under
C:\Inetpub\wwwroot\RSWebNET?
Are the mechanisms that are supped eliminate DLL-hell actually creating a
new DLL-hell on my behalf?
Am I missing some fundamental clues, and if so, can you refer me to an
informative link or two?

I sincerely appreciate any time you spend reading and responding to this. I
hope I can help you folks at some point in the future. Thanks in advance
for your time and words!

James Hunter RossI'm not positive where you are getting the duplicate definition's from,
but to answer your other question, those DLL's are being created under
those temporary directories so that ASP.NET can lock the files for use
for the web server, but allowing you to edit the application at the
same time. It's basically shadow copies.

As for your your other problem, it looks like you are defining a class
InventoryGrid in inventorygrid.aspx, and using a reference to
RSWebNET.DLL which defines InventoryGrid as well, but it's hard to
tell.

Darren Kopp
http://blog.secudocs.com/