OData v4 Function always returns 404

Question

Trying to move from OData v3 to OData v4. Why do I keep getting a 404 when trying to use OData Functions?

Web API Config:

ODataModelBuilder builder = new ODataConventionModelBuilder();
//etc
builder.EntitySet<LocalizableString>("LocalizableStringApi");
//etc
var getComparitiveTableFunction = builder.EntityType<LocalizableString>().Collection.Function("GetComparitiveTable");
getComparitiveTableFunction.Parameter<string>("cultureCode");
getComparitiveTableFunction.ReturnsCollection<ComparitiveLocalizableString>();
//etc
config.MapODataServiceRoute("OData_Kore_CMS", "odata/kore/cms", builder.GetEdmModel());

C# Code:

[EnableQuery(AllowedQueryOptions = AllowedQueryOptions.All)]
[HttpGet]
//[ODataRoute("Default.GetComparitiveTable(cultureCode={cultureCode})")] // Tried this, but gets errors and I noticed the function is in the OData model anyway without this, so should be fine.
public virtual IHttpActionResult GetComparitiveTable([FromODataUri] string cultureCode)
{
    // Implementation
    return Ok(query);
}

XML Returned from $metadata:

<Schema Namespace="Default">
    <Function Name="GetComparitiveTable" IsBound="true">
        <Parameter Name="bindingParameter" Type="Collection(Kore.Localization.Domain.LocalizableString)"/>
        <Parameter Name="cultureCode" Type="Edm.String" Unicode="false"/>
        <ReturnType Type="Collection(Kore.Localization.Models.ComparitiveLocalizableString)"/>
    </Function>
    ...

As you can see, it's in the schema / OData model... yet the following query does not work:

http://localhost:30863/odata/kore/cms/LocalizableStringApi/Default.GetComparitiveTable(cultureCode='en-US')

I have also tried the following:

http://localhost:30863/odata/kore/cms/LocalizableStringApi/GetComparitiveTable(cultureCode='en-US')
http://localhost:30863/odata/kore/cms/Default.GetComparitiveTable(cultureCode='en-US')
http://localhost:30863/odata/kore/cms/GetComparitiveTable(cultureCode='en-US')

All of the above result in a 404.

So... what am I doing wrong here?

Answer 1

I solved this by adding the following line in my web.config, under <system.webServer>:

<modules runAllManagedModulesForAllRequests="true">

This may cause performance issues though, if I remember correctly. So it's not ideal. Any better solutions are very welcome...