Only outputs the inner layout when the specified condition has been met. See Conditions page.

Supported in .NET, Silverlight, Compact Framework and Mono.

##Configuration Syntax

${when:when=Condition:inner=Layout:else=Layout}

or by using ambient property to modify output of other layout renderer:

${other:when=Condition}

##Parameters ###Transformation Options

• when - Condition that must be met for the inner layout to be printed. Condition Required.
• inner - Wrapped layout. Layout
• else - Layout if the condition is not true (introduced in NLog 4.3.5)

##Examples

• {message:when=logger=='logger'}: print the message when the logger name is equal to "logger".
• ${when:when='${aspnet-request:serverVariable=HTTPS}' == 'on'}:inner=1:else:0} convert a layout string result to a bit (1 or 0) that can be inserted into a SQL bit field.

##Escaping

When using : and } in a internal layout those characters need to be scape (there is no need to scape \).

• : because it's a value separator.
• } because it's the end of the layout

Working examples:

• ${when:when=1 == 1:Inner=Test\: Hello}
• ${when:when=1 == 1:Inner=Test\\Hello}
• ${when:when=1 == 1:Inner=Test\Hello}
• ${when:when=1 == 1:Inner=Test{Hello\}}

###Before 4.2

The colon (:) character should be wrapped within {literal:text=\:} instead of placed directly within the inner layout.

Working Example

Non-working Example

When the colon character is not wrapped only the last literal instance, in this case the word 'World', appears.

⭐ Workaround identified by: @reedyrm