[Blazor webassembly] library not working with linker disabled

[julienGrd]

Hello and thanks for your work ! I use your library in one of my blazor webassembly project, but it seem not working when the linkler is disabled

You will find a reproduction project here : https://github.com/julienGrd/blazorWebassembly3.2Preview1

• run the app
• go to fetch data
• open the chrome console, you will see this exception

System.TypeInitializationException: The type initializer for 'System.Linq.Dynamic.Core.DynamicQueryableExtensions' threw an exception. ---> System.Exception: Specific method not found: All ---> System.InvalidOperationException: Sequence contains no matching element

It seem this issue is related to this one on mono, if it can help : mono/mono#12917

if you disable the linker(in the webassembly csproj) there is no longer problem, but it's not a good thing and make the app bigger

 <PropertyGroup>
    <BlazorWebAssemblyEnableLinking>false</BlazorWebAssemblyEnableLinking>
  </PropertyGroup>

thanks for your help !

[StefH]

Is this something which can be fixed by this library, or just as notification?

[julienGrd]

I'm not really sure... at the end of the issue (this one mono/mono#12917) they speak about a PreserveDependencyAttribute which can be add to solve the problem but we have a lack of information. So if you understand what they speak about in the issue maybe you can make something but otherwise i will wait for more information.

[StefH]

If that property solves the issue, that means that property should be defined in the calling application, cannot be defined in this project.

I think...

[julienGrd]

apparently the guys of mono back to us in the month to explain, we will see at this moment.
Im not the only who use this library in blazor webassembly app so anyway it can be nice to put the solution here, even if it impact only the calling app and not the library itselve

[danroth27]

Hi @julienGrd. You should be able to configure the linker for your library by embedding an XML linker config file into the library. I've put together a sample that shows how to do this here: https://github.com/danroth27/ComponentLibWithXmlLinkerConfig. Could you please try this out and see if it works for your scenario?

[julienGrd]

Hi @danroth27 , thanks it seem work perfectly ! just an important thing to make it works, i have to add the file at the project but also edit the csproj to add this directive (like your project)

<ItemGroup>
        <EmbeddedResource Include="LinkerConfig.xml">
            <LogicalName>$(MSBuildProjectName).xml</LogicalName>
        </EmbeddedResource>
    </ItemGroup>

Is this file not impact other .NET standard type of project? because its not a blazor specific library !

@StefH : OK to add this to your project ? otherwise it seem i can make it directly on my client project

[danroth27]

Is this file not impact other .NET standard type of project? because its not a blazor specific library !

All this is doing is embedded the XML linker config file into the assembly. This file will get picked up appropriately by the .NET IL linker wherever it gets used, including Xamarin apps and standalone .NET Core desktop apps. For apps that aren't using the linker this file is completely benign.

In short, this file is not Blazor specific and is safe to add to any .NET Standard library.

[julienGrd]

@danroth27 finally It seem not enough with this library. I fall into another problems when i try to use dynamic group by.
To reproduce :

• open your ComponentLibWithXmlLinkerConfigproject
• put this piece of code on the Initialized of your component
  var test = people.AsQueryable().GroupBy("Name").ToDynamicList<IGrouping<dynamic, Person>>();

you will have this error :

blazor.webassembly.js:1 WASM: System.TypeInitializationException: The type initializer for 'System.Linq.Dynamic.Core.DynamicEnumerableExtensions' threw an exception. ---> System.InvalidOperationException: Sequence contains no matching element
blazor.webassembly.js:1 WASM:   at System.Linq.Enumerable.First[TSource] (System.Collections.Generic.IEnumerable`1[T] source, System.Func`2[T,TResult] predicate) <0x21b7380 + 0x00022> in <filename unknown>:0 
at System.Linq.Dynamic.Core.DynamicEnumerableExtensions..cctor () <0x21b6f98 + 0x0002a> in <filename unknown>:0 

What is strange, is im unable to reproduce this error when i reference the csproj of this project, its only when i reference the nuget package.

@StefH : some idea on this ?

[danroth27]

@julienGrd Makes sense - the type initializer for DynamicEnumerableExtensions uses reflection: https://github.com/StefH/System.Linq.Dynamic.Core/blob/master/src/System.Linq.Dynamic.Core/DynamicEnumerableExtensions.cs#L16-L20. You could address this by updating the xml linker config to preserve the DynamicEnumerableExtensions type.

[julienGrd]

Yes i was thinking was something like that, i still don't really understand how to use the linker :-/. i try both these configuration without make it work

  <assembly fullname="System.Reflection">
    <type fullname="System.Linq.Dynamic.Core.DynamicEnumerableExtensions" preserve="all" />
  </assembly>

<assembly fullname="System.Runtime">
    <type fullname="System.Linq.Dynamic.Core.DynamicEnumerableExtensions" preserve="all" />
  </assembly>

[danroth27]

@julienGrd DynamicEnumerableExtensions lives in the System.Linq.Dynamics.Core assembly, not System.Runtime.

[julienGrd]

ok it works perfect ! i will be happy to have some documentations about the linker when it will be possible !
Thanks for your help i will close this issue.

@StefH if you still want include by default this configuration to make it works in mono projects without client configuration, i can suggest a PR. just reopen this issue and say me.

[danroth27]

@julienGrd Docs on how to configure the linker for libraries are in the works: dotnet/AspNetCore.Docs#17369

[julienGrd]

the final solution to make it works, on the library or on the client project
Linker.xml

<?xml version="1.0" encoding="utf-8" ?>
<!-- IL linker format: https://github.com/mono/linker#link-xml-file-examples -->
<linker>
  <assembly fullname="System.Core">
    <type fullname="System.Linq.Queryable" preserve="all" />
  </assembly>
  <assembly fullname="System.Linq.Dynamic.Core">
    <type fullname="System.Linq.Dynamic.Core.DynamicEnumerableExtensions" preserve="all" />
  </assembly>
</linker>

csproj

<ItemGroup>
    <None Remove="LinkerConfig.xml" />
  </ItemGroup>
  <ItemGroup>
    <EmbeddedResource Include="LinkerConfig.xml">
      <LogicalName>$(MSBuildProjectName).xml</LogicalName>
    </EmbeddedResource>
  </ItemGroup>