Gurobi 11.0 nuget package and netstandard 2.0

Answered

Christoph Hofer-Temmel

February 26, 2024 12:48

• 
• 
• 

 Our use case is: We develop F# libraries (netstandard2.0 and MSIL) wrapping Gurobi. The resulting libraries are handed over the operations side, but also tested interactively with fsi (F# interpreter).

In particular, our dependency chain looks like: Gurobi nuget package => F# project 1 => ... => F# project n. 

Since Gurobi 10 there is an official nuget package: How do I use Gurobi with NuGet? – Gurobi Help Center. We wanted to use it instead of vendoring the relevant dlls by hand.

When integrating Gurobi via a NuGet PackageReference
 

<PackageReference Include="Gurobi.Optimizer" Version="11.0.0" />

 
into a project with 

<TargetFrameworks>netstandard2.0</TargetFrameworks> 

only the gurobi110.netstandard20.dll gets copied
to the output directory. When executing the code this results in the following error:
 

System.DllNotFoundException: Unable to load DLL 'gurobi110' or one of its dependencies: The 

The error message is correct because the gurobi110.dll is not present in the output directory.

The dll is only copied to the output directory by this PreBuildEvent inside the Gurobi nuget package, which only copies the dll when the TargetFramework is e.g. net48 but not when it's netstandard2.0.

<Target
  Name="Windows Build"
  AfterTargets="PreBuildEvent"
  Condition="($(TargetFramework.TrimEnd('0123456789')) == 'net' OR $(TargetFramework) == '') AND $([MSBuild]::IsOSPlatform('Windows'))">
    <Copy DestinationFolder="$(OutputPath)" SourceFiles="$(MSBuildThisFileDirectory)..\runtimes\win-x64\native\gurobi100.dll" />
</Target>

This blocks our usage of the Gurobi nuget package. How can we include gurobi110.dll in the build folders of all our projects 1 to n?

Related to

• .NET

0

• 

  Elisabeth Rodríguez Heck

  • Gurobi Staff

  February 28, 2024 09:53

  This was handled in a ticket.

  0
• 

  Christoph Hofer-Temmel

  March 11, 2024 09:46

  • 
  • 
  • 

  Just to make some of the non-private ticket information public:
  
  1) Adding the missing information to the nuget package (i.e., for `netstandard`) solves this problem only with the first project. Projects 2 to n do not get a copy of the Gurobi libraries. This seems to be an old MSBuild based build-chain limitation. See https://stackoverflow.com/questions/856278/why-the-native-dll-is-not-copied-to-the-output-directory.
       1a) You can work around this by a direct reference to the Gurobi nuget package.
       1a) Or do a custom post-build action.
       1c) You can add a <RuntimeIdentifiers>...</RuntimeIdentifiers> in each downstream project.
                * This builds with a single RID.
                * With multiple RIDs this needs a build flag to choose a RID.
                * This looses "full" netstandard, but works as the interactive use case has an intelligent user in front of the screen ... and we know where we currently run.
       1d) You can switch to exe instead of Library for your project type. Loosing netstandard.
  
  

   

  0

Please sign in to leave a comment.