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 :)

Hatti

It is not a language. File is only read and is XML format. – Everything

The OP is speaking of the embedded expressions like [System.DateTime]::UtcNow.ToString(mmff). – Shiah

Looks a bit like PowerShell – Humanoid

I would not recommend using time to produce version numbers. It can break MSBuild's incremental build model and produce longer build times. – Incorrupt

Saw this example about semantic versioning. It uses git's commit info instead of time – Tanner

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

Parable

new DateTime could be used as e.g. $([System.DateTime]::new(2021,1,1)) – Haunt

@Haunt good to know. I'll add to my answer. Thanks. – Parable

Is this supported by any compiler of the .NET platform (Framework and/or Core, Mono...), or only dedicated to Visual Studio? – Inflammable

@OlivierRogier it's MSBuild, so presumably it would work outside of VS. – Parable

DayOfAYear will only work with 1st of January then ) if I have the first day of February will not.... – Hatti

@Serge sorry not following you. Maybe you don't need <January> at all then...? – Parable

I mean, if we put the december 2020 then it would be a negative value, because in december 2020 DayOfYear will be greater than in January or Mai 2021... – Hatti

Based on the fact you have a node called DaysFromLastRelease it sounds like you are wanting to calculate Now - LastBuildDate and then get that in a # of days right? What I provided in my answer is kind of hardcoded, so that's why I said it would be a base, and not a full solution. Full solution would have to account for oddities such as a negative value. MSBuild while powerful, may have met its match in what you want to do... not sure ;) – Parable

not working of DayOfYear of the last date is less than the DayOfYear of previous date (if next year) – Hatti

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.

Tenure

I added .Date after UtcNow - the TotalDays implementation rounds PM to the next day, which breaks the strict increasing logic <VersionPatch Condition="'$(VersionPatch)' == ''">$([System.DateTime]::UtcNow.Date.Subtract($([System.DateTime]::new(2001, 1, 1))).TotalDays.ToString("0"))</VersionPatch> – Intermediate

I tested it and it works for me. My PC is set to use 24h format by default, maybe that's the point here. – Zacynthus