T4 Templating with 3rd party assemblies

Question

I have the need to do JSON schema generation within a T4 template, and found Newtonsoft's new Schema class more than adequate for the purpose at hand (within a console application, tested), however, I cannot seem to make it play ball with the rest, as the instance to Newtonsoft always returns null.

T4 declaration:

<#@ template debug="true" hostspecific="true" language="C#" #>
<#@ assembly name="System.Core" #>
<#@ assembly name="Newtonsoft.Json.dll" #>
<#@ assembly name="Newtonsoft.Json.Schema.dll" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ output extension=".cs" #>

The assembly references point to the DLL files, and I have folder look ups set in the project settings for the project, screen shot below:

Trying to do something like the below, fails, because Newtonsoft cannot be found:

var schema = Newtonsoft.Json.Schema.JSchema.Parse(jsoncontent);

Error thrown is: Metadata file 'Newtonsoft.Json.Schema.dll" could not be found.

Answer 1

T4 templates do not use the reference path defined in the project. T4 does support some variables inside Visual Studio:

<#@ assembly name="$(SolutionDir)\MyProject\bin\Debug\SomeLibrary.Dll" #>

There is an existing StackOverflow question about this.

If you are referencing the .dll and it is being copied into the output directory you should be able to use $(TargetDir) in the path so you do not need to include the NuGet package version number which will change when you update the NuGet package.