Patching in a custom StandardValues provider

Question

I am trying to add a custom StandardValues provider to a Sitecore 8.1 site (8.1.0 rev 160519) and I am not having a good time.

To do this I reflected the standard Sitecore.Data.StandardValuesProvider in Sitecore.Kernel, copied all the codez and made the change I want. It compiles, so I assume it'll work :D

btw I am modifying the behaviour of private SafeDictionary<ID, string> GetStandardValues(Item item), for reasons

I attempt to wire up the patch thusly: -

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <standardValues>
      <providers>
        <add name="sitecore">
          <patch:attribute name="type">[REDACTED].Web.Sitecore.Providers.[REDACTED]StandardValuesProvider, [REDACTED].Web</patch:attribute>
        </add>
      </providers>
    </standardValues>
  </sitecore>
</configuration>

But although my patch looks like it's worked in /showconfig.aspx, the site itself doesn't load: -

Server Error in '/' Application.

Unexpected provider type: 

[REDACTED].Web.Sitecore.Providers.[REDACTED]StandardValuesProvider

Expected: Sitecore.Data.StandardValuesProvider

Kind of like.. it doesn't want to see another kind of provider besides the default one ?

Has anyone tried to do this and succeeded ?

Answer 1

As Kasper Gadensgaard mentioned in the comments, the StandardValuesManager requires a provider inherited from the StandardValuesProvider class:

public static class StandardValuesManager
{
    private static readonly ProviderHelper<StandardValuesProvider, StandardValuesProviderCollection> _helper = 
        new ProviderHelper<StandardValuesProvider, StandardValuesProviderCollection>("standardValues");
    ...
}