How can Xml Documentation for Web Api include documentation from beyond the main project?

Question

The documentation for enabling XmlDoc integration into your Web Api projects appears to only handle situations where all of your API types are part of your WebApi project.

Answer 1

I ran into this too, but I didn't want to edit or duplicate any of the generated code to avoid problems later.

Building on the other answers, here's a self-contained documentation provider for multiple XML sources. Just drop this into your project:

/// 
A custom  that reads the API documentation from a collection of XML documentation files.
public class MultiXmlDocumentationProvider : IDocumentationProvider, IModelDocumentationProvider
{
    /*********
    ** Properties
    *********/
    /// 
The internal documentation providers for specific files.
    private readonly XmlDocumentationProvider[] Providers;


    /*********
    ** Public methods
    *********/
    /// 
Construct an instance.
    /// The physical paths to the XML documents.
    public MultiXmlDocumentationProvider(params string[] paths)
    {
        this.Providers = paths.Select(p => new XmlDocumentationProvider(p)).ToArray();
    }

    /// 
Gets the documentation for a subject.
    /// The subject to document.
    public string GetDocumentation(MemberInfo subject)
    {
        return this.GetFirstMatch(p => p.GetDocumentation(subject));
    }

    /// 
Gets the documentation for a subject.
    /// The subject to document.
    public string GetDocumentation(Type subject)
    {
        return this.GetFirstMatch(p => p.GetDocumentation(subject));
    }

    /// 
Gets the documentation for a subject.
    /// The subject to document.
    public string GetDocumentation(HttpControllerDescriptor subject)
    {
        return this.GetFirstMatch(p => p.GetDocumentation(subject));
    }

    /// 
Gets the documentation for a subject.
    /// The subject to document.
    public string GetDocumentation(HttpActionDescriptor subject)
    {
        return this.GetFirstMatch(p => p.GetDocumentation(subject));
    }

    /// 
Gets the documentation for a subject.
    /// The subject to document.
    public string GetDocumentation(HttpParameterDescriptor subject)
    {
        return this.GetFirstMatch(p => p.GetDocumentation(subject));
    }

    /// 
Gets the documentation for a subject.
    /// The subject to document.
    public string GetResponseDocumentation(HttpActionDescriptor subject)
    {
        return this.GetFirstMatch(p => p.GetResponseDocumentation(subject));
    }


    /*********
    ** Private methods
    *********/
    /// 
Get the first valid result from the collection of XML documentation providers.
    /// The method to invoke.
    private string GetFirstMatch(Func expr)
    {
        return this.Providers
            .Select(expr)
            .FirstOrDefault(p => !String.IsNullOrWhiteSpace(p));
    }
}

...and enable it in your HelpPageConfig with the paths to the XML documents you want:

config.SetDocumentationProvider(new MultiXmlDocumentationProvider(HttpContext.Current.Server.MapPath("~/App_Data/Api.xml"), HttpContext.Current.Server.MapPath("~/App_Data/Api.Models.xml")));