visual studio - Check if PropertyGroup item is set to a value in .csproj -

i using .targets files include common functionality in .csproj files.

in target file, want check if property set before, , if yes, not set again.

i need because using specific target file in many solutions, , want include custum property if wasn't set before.

the property talking

<propertygroup> <codeanalysisruleset>$(solutiondir)customizedallrules.ruleset</codeanalysisruleset> </propertygroup>

if ruleset specified before importing target file, don't want include again in .targets file.

how check in .csproj if <codeanalysisruleset>...</codeanalysisruleset> set before?

the pattern i've seen set conditionally based on comparing empty value:

<propertygroup>     <codeanalysisruleset condition="'$(codeanalysisruleset)' == ''">$(solutiondir)customizedallrules.ruleset</codeanalysisruleset> </propertygroup> 

[edit: responding comment code example]

here's longer example works me:

<project toolsversion="4.0" defaulttargets="build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">     <propertygroup>         <propertyvalue condition="$(propertyvalue) == ''">default value</propertyvalue>     </propertygroup>     <target name="build">         <message text="$(propertyvalue)" />     </target> </project> 

gives console output:

project "d:\temp\test.proj" on node 1 (default targets). build:   default value done building project "d:\temp\test.proj" (default targets).