How do I get the difference between two dates in a .csproj file?

Question

I saw some code like this , in a csproj file

$([System.DateTime]::UtcNow.ToString(mmff))

to autoincrement the assembly version:

<VersionSuffix>2.0.0.$([System.DateTime]::UtcNow.ToString(mmff))</VersionSuffix>
<AssemblyVersion Condition=" '$(VersionSuffix)' == '' ">0.0.0.1</AssemblyVersion>

What kind of language/script is that? How do I use it to get the difference between two dates?

I tried to do something like this:

<VersionMajor>2</VersionMajor>
<VersionMinor>1</VersionMinor>
<DaysFromLastRelease>$(([System.DateTime]::UtcNow - new [System.DateTime](2021,1,1))::TotalDays)</DaysFromLastRelease>

but it does not work:)

Answer 1

.csproj files are basically MSBuild files (XML). The embedded syntax you are referring to is called a Property Function .

It appears that subtraction using the minus ( - ) might not be supported. There is a Subtract() property function in Property Functions .

Perhaps this could be the base for a solution. I have not tried it!

<Now>$([System.DateTime]::UtcNow.DayOfYear)</Now>

<January>$([System.DateTime]::new(2021,1,1)).DayOfYear</January>
<!-- or... (not sure about the below)
<January>$([System.DateTime]::Parse("1/1/2021").DayOfYear)</January>
 -->

<DaysFromLastRelease>$([MSBuild]::Subtract($(Now), $(January)))</DaysFromLastRelease>

Other possibilities

• calculate the date difference by writing an MSBuild task
• call out to a simple program you write
• somehow use an external program to set an environment variable, and then reference that variable in your .csproj

Answer 2

That's what worked for me:

<PropertyGroup>
    <VersionMajor Condition="'$(VersionMajor)' == ''">0</VersionMajor>
    <VersionMinor Condition="'$(VersionMinor)' == ''">0</VersionMinor>
    <VersionPatch Condition="'$(VersionPatch)' == ''">$([System.DateTime]::UtcNow.Subtract($([System.DateTime]::new(2001,1,1))).TotalDays.ToString("0"))</VersionPatch>
    <VersionRevision Condition="'$(VersionRevision)' == ''">$([System.DateTime]::UtcNow.TimeOfDay.TotalMinutes.ToString("0"))</VersionRevision>
    <Version>$(VersionMajor).$(VersionMinor).$(VersionPatch).$(VersionRevision)</Version>
</PropertyGroup>

Here I manually set VersionMajor and VersionMinor. Then I have autoincremented values for Patch and revision.

• Patch: number of days since 2001/01/01 (first day of century XXI).
• Revision: total minutes of the day

That's good enought untill June 2180 (Remember máx versión number is 65534).

---

Extra tip: I put all this lines into a Version.Build.props file into Properties folder. Then I import it from csproj file with this tag:

<Import Project="$([MSBuild]::GetPathOfFileAbove('Version.Build.props', '$(MSBuildThisFileDirectory)/Properties/'))" />

This way, I can manually set proyect versions manually in my csproj file, left them in auto or a mix of them by just setting VersionMajor and VersionMinor which is what I actually do.