Newtonsoft.Json reference complaining on Azure Functions

@JustInChronicles, I'm adding this here as an answer for reference, but the expected behavior should be that indirect dependencies of private assemblies are resolved from your bin folder, as expected.

I put together the following test to reproduce your scenario:

• Created a simple class library with a simple type that uses Json.NET to serialize an object and return the JSON string. This assembly references Json.NET 8.0.3. The result includes the Json.NET assembly version it is using
• Created a function that references that type only with a #r "DependencyWithJsonRef.dll" and returns the result produced by the method mentioned above
• Deployed DependencyWithJsonRef.dll and Newtonsoft.Json.dll (8.0.3) to my function's bin folder

Invoking the function produces the expected result.

Here is the function, for reference:

#r "DependencyWithJsonRef.dll"

using System.Net;

public static string Run(HttpRequestMessage req, TraceWriter log)
{
    var myType = new DependencyWithJsonRef.TestType();
    return myType.GetFromJson();
}

As you can see, no explicit reference to indirect dependencies (Json.NET) required.

This is the output I get:

{
    "Prop1":"Test",
    "Prop2":1,
    "AssemblyName": "Newtonsoft.Json, Version=8.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed"
}

Quick note: One thing you may want to check, particularly if you've updated that dependency while developing your function is that assembly resultion results were not cached. A sure way to make sure you're starting with a clean slate is to (after you deploy your function and assemblies) go to Kudu and kill the non-scm w3wp process to see if that helps. I'd be curious to know if that does the trick as there are a few things we can to to improve this if it does.

After some trial-and-error approach. I found what the issue was here.

@FabioCavalcante gave me a hint using a file-based reference,

#r "Newtonsoft.Json.dll"

It didn't work actually. I've copied those four files to Azure Functions' bin directory:

• AzureFunctionsSample.Services.dll
• AzureFunctionsSample.Services.pdb
• Newtonsoft.Json.dll
• Newtonsoft.Json.xml

It still gave me the same error, even though I did the file-based reference. Then, I found another file, AzureFunctionsSample.Services.dll.config that actually defines assembly binding redirects like:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-8.0.0.0" newVersion="8.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

After I copied this config file to the Azure Functions' bin directory, it worked!

Lessons Learnt

• Use the file-based reference for Newtonsoft.Json, #r "Newtonsoft.Json.dll", if your external assembly also has a reference to it.
• Make sure that the assembly binding redirect configuration exists in Azure Functions' bin directory.

Correct me, if I'm still wrong.

Cheers,