TraceContext.Write Method

Definition

Namespace:

System.Web

Assembly:

System.Web.dll

Writes trace information to the trace log.

Overloads

Write(String)	Writes a trace message to the trace log.
Write(String, String)	Writes trace information to the trace log, including a message and any user-defined categories.
Write(String, String, Exception)	Writes trace information to the trace log, including any user-defined categories, trace messages, and error information.

Write(String)

Writes a trace message to the trace log.

public:
 void Write(System::String ^ message);

public void Write (string message);

member this.Write : string -> unit

Public Sub Write (message As String)

Parameters

message

String

The trace message to write to the log.

Remarks

Every time the Write method is called, a TraceContext trace message is added to the TraceRecords messages collection, which is accessible when you handle the TraceFinished event. The message is added with its IsWarning property set to false and its ErrorInfo property set to null.

See also

• ASP.NET Tracing Overview

Write(String, String)

Writes trace information to the trace log, including a message and any user-defined categories.

public:
 void Write(System::String ^ category, System::String ^ message);

public void Write (string category, string message);

member this.Write : string * string -> unit

Public Sub Write (category As String, message As String)

Parameters

category

String

The trace category that receives the message.

message

String

The trace message to write to the log.

Examples

The following code example demonstrates how to call the Write method to write an error trace message to the trace log. In this example, the delegate iterates through the trace messages and writes them as an HTML table; however, you can write the same information to a database or a profiling tool consumer.

<%@ Page language="c#" Trace="true" %>
<script runat="server">
void Page_Load(object sender, EventArgs e)
{
    // Register a handler for the TraceFinished event.
    Trace.TraceFinished += new 
        TraceContextEventHandler(this.OnTraceFinished);

    // Write a trace message.
    Trace.Write("Web Forms Infrastructure Methods", "USERMESSAGE: Page_Load complete.");
}
 
// A TraceContextEventHandler for the TraceFinished event.
void OnTraceFinished(object sender, TraceContextEventArgs e)
{
    TraceContextRecord r = null;    
    
    // Iterate through the collection of trace records and write 
    // them to the response stream.
    Response.Write("<table>");
    foreach(object o in e.TraceRecords)
    {
        r = (TraceContextRecord)o;
        Response.Write(String.Format("<tr><td>{0}</td><td>{1}</td></tr>", r.Message, r.Category));        
    }
    Response.Write("</table>");
}       
</script>

<%@ Page language="VB" Trace="true" %>
<script runat="server">
' The Page_Load method.
Private Sub Page_Load(sender As Object, e As EventArgs)

    ' Register a handler for the TraceFinished event.
    AddHandler Trace.TraceFinished, AddressOf OnTraceFinished

    ' Write a trace message.
    Trace.Write("Web Forms Infrastructure Methods", "USERMESSAGE: Page_Load complete.")
End Sub ' Page_Load
 
' A TraceContextEventHandler for the TraceFinished event.
Private Sub OnTraceFinished(sender As Object, e As TraceContextEventArgs)

    Dim r As TraceContextRecord
    Dim o As Object
    
    ' Iterate through the collection of trace records and write 
    ' them to the response stream.
    Response.Write("<table>")
    For Each o In e.TraceRecords
        r = CType(o, TraceContextRecord)
        Response.Write(String.Format("<tr><td>{0}</td><td>{1}</td></tr>", r.Message, r.Category))
    Next
    Response.Write("</table>")

End Sub ' OnTraceFinished
</script>

Remarks

Every time the Write method is called, a TraceContext trace message is added to the TraceRecords messages collection, which is accessible when you handle the TraceFinished event. The message is added with its IsWarning property set to false and its ErrorInfo property set to null.

See also

• ASP.NET Tracing Overview

Write(String, String, Exception)

Writes trace information to the trace log, including any user-defined categories, trace messages, and error information.

public:
 void Write(System::String ^ category, System::String ^ message, Exception ^ errorInfo);

public void Write (string category, string message, Exception errorInfo);

member this.Write : string * string * Exception -> unit

Public Sub Write (category As String, message As String, errorInfo As Exception)

Parameters

category

String

The trace category that receives the message.

message

String

The trace message to write to the log.

errorInfo

Exception

An Exception that contains information about the error.

Examples

The following code example demonstrates how to call the Write method to write an error trace message to the trace log. In this example, different exceptions are traced as errors and warnings. When the page throws an ArgumentException, it writes a warning message using the Warn method. When the page throws an InvalidOperationException, it writes an error message using the Write method.

<%@ Page language="c#" Trace="true" %>
<script runat="server">
void Page_Load(object sender, EventArgs e)
{
    // Register a handler for the TraceFinished event.
    Trace.TraceFinished += new 
        TraceContextEventHandler(this.OnTraceFinished);

    try {
        throw new ArgumentException("Trace Test");
    }
    catch (InvalidOperationException ioe) {    
        // You can write an error trace message using the Write method.
        Trace.Write("Exception Handling", "Exception: Page_Load.", ioe);
    }
    catch (ArgumentException ae) {    
        // You can write a warning trace message using the Warn method.
        Trace.Warn("Exception Handling", "Warning: Page_Load.", ae);
    }
}
 
// A TraceContextEventHandler for the TraceFinished event.
void OnTraceFinished(object sender, TraceContextEventArgs e)
{
    TraceContextRecord r = null;    
    
    // Iterate through the collection of trace records and write 
    // them to the response stream.
    foreach(object o in e.TraceRecords)
    { 
        r = (TraceContextRecord)o;
        if (r.IsWarning) {
            Response.Write(String.Format("warning message: {0} <BR>", r.Message));
        }
        else {
            Response.Write(String.Format("error message: {0} <BR>", r.Message));
        }

    }
}       
</script>

<%@ Page language="VB" Trace="true" %>
<script runat="server">
' The Page_Load method.
Private Sub Page_Load(sender As Object, e As EventArgs)

    ' Register a handler for the TraceFinished event.
    AddHandler Trace.TraceFinished, AddressOf OnTraceFinished

    Try 
    Dim ae As New ArgumentException("Trace Test")
        Throw ae
    
    catch ioe As InvalidOperationException
        ' You can write an error trace message using the Write method.
        Trace.Write("Exception Handling", "Exception: Page_Load.", ioe)
    
    Catch ae As ArgumentException
        ' You can write a warning trace message using the Warn method.
        Trace.Warn("Exception Handling", "Warning: Page_Load.", ae)

    End Try

End Sub ' Page_Load
 
' A TraceContextEventHandler for the TraceFinished event.
Private Sub OnTraceFinished(sender As Object, e As TraceContextEventArgs)

    Dim r As TraceContextRecord
    Dim o As Object
    
    ' Iterate through the collection of trace records and write 
    ' them to the response stream.

    For Each o In e.TraceRecords
        r = CType(o, TraceContextRecord)
    If r.IsWarning Then
            Response.Write(String.Format("warning message: {0} <BR>", r.Message))
        Else
            Response.Write(String.Format("error message: {0} <BR>", r.Message))
        End If
    Next

End Sub	' OnTraceFinished
</script>

Remarks

Every time the Write method is called, a TraceContext trace message is added to the TraceRecords messages collection, which is accessible when you handle the TraceFinished event. The message is added with its IsWarning property set to false, and the ErrorInfo property is set to the object passed by the errorInfo parameter.

See also

• Exception
• ASP.NET Tracing Overview