Question

http://logging.apache.org/log4net/release/config-examples.html

Given the log table here:

CREATE TABLE [dbo].[Log] (
    [Id] [int] IDENTITY (1, 1) NOT NULL,
    [Date] [datetime] NOT NULL,
    [Thread] [varchar] (255) NOT NULL,
    [Level] [varchar] (50) NOT NULL,
    [Logger] [varchar] (255) NOT NULL,
    [Message] [varchar] (4000) NOT NULL,
    [Exception] [varchar] (2000) NULL,

    [Product] [varchar] 100 not null
)

and the appender config here:

<appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender">
    <bufferSize value="100" />
    <connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
    <connectionString value="data source=[database server];initial catalog=[database name];integrated security=false;persist security info=True;User ID=[user];Password=[password]" />
    <commandText value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message],[Exception], [Product]) VALUES (@log_date, @thread, @log_level, @logger, @message, @exception, @product)" />
    <parameter>
        <parameterName value="@log_date" />
        <dbType value="DateTime" />
        <layout type="log4net.Layout.RawTimeStampLayout" />
    </parameter>
    <parameter>
        <parameterName value="@thread" />
        <dbType value="String" />
        <size value="255" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%thread" />
        </layout>
    </parameter>
    <parameter>
        <parameterName value="@log_level" />
        <dbType value="String" />
        <size value="50" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%level" />
        </layout>
    </parameter>
    <parameter>
        <parameterName value="@logger" />
        <dbType value="String" />
        <size value="255" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%logger" />
        </layout>
    </parameter>
    <parameter>
        <parameterName value="@message" />
        <dbType value="String" />
        <size value="4000" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%message" />
        </layout>
    </parameter>
    <parameter>
        <parameterName value="@exception" />
        <dbType value="String" />
        <size value="2000" />
        <layout type="log4net.Layout.ExceptionLayout" />
    </parameter>
</appender>

How can I add a constant parameter for the “product” column- without any code changes? Config-only change if possible!

For example, I want to do something like this:

<parameter>
    <parameterName value="@product" />
    <dbType value="String" />
    <size value="100" />

    <constantValue value="Product A" /> <!-- how do i do this? -->

</parameter>

EDIT: The answer is simple. Edit the command text!

<commandText value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message],[Exception], [Product]) VALUES (@log_date, @thread, @log_level, @logger, @message, @exception, 'Product A')" />

Answer 1

While you could simply add a ‘SomeConstant’ value to the insert statement, we use the following method with the AdoNetAppender. We add a @source column to our log table so we can have many servers all logging to the same table, yet give us some SYSLOG like functionality.

  ...
  <commandText value="INSERT INTO Log ([Date],[Source],[Level],[Logger],[Message],[Exception]) VALUES (@log_date, @source, @log_level, @logger, @message, @exception)" />

  ...
  <parameter>
    <parameterName value="@source"/>
    <dbType value="String"/>
    <size value="32"/>
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="WEB1"/>
    </layout>
  </parameter>

The PatternLayout readily accepts string constants, why complicate it!

Enjoy.