Dependency injection into custom ViewPage generates weird error

Question

i'm trying to inject stuff into a custom ViewPage (ModelViewPage, from MvcContrib)

public class ValidatedModelViewPage<T> : ModelViewPage<T> where T : class
    {
        public ValidatedModelViewPage(IEnumerable<IBehavior<IMemberElement>> elementBehaviors)
           : base(elementBehaviors.ToArray()) { }
    }

and my Autofac registrations look like this:

            builder.RegisterCollection<IBehavior<IMemberElement>>().As<IEnumerable<IBehavior<IMemberElement>>>();
            builder.Register<NotNullBehavior>().MemberOf<IEnumerable<IBehavior<IMemberElement>>>();
            builder.Register<StringLenghBehavior>().MemberOf<IEnumerable<IBehavior<IMemberElement>>>();

            builder.RegisterGeneric(typeof(ValidatedModelViewPage<>));

but i get this error when i try to access a view:

Compiler Error Message: CS1729: 'UKFS.Web.Views.ValidatedModelViewPage<UKFS.Data.Entities.Skadeanmälan>' does not contain a constructor that takes '0' arguments

Source Error:

Line 194:        private static object @__fileDependencies;
Line 195:        
Line 196:        [System.Diagnostics.DebuggerNonUserCodeAttribute()]
Line 197:        public views_skadeanmälan_edit_aspx() {
Line 198:            string[] dependencies;


Source File: c:\Users\Carl\AppData\Local\Temp\Temporary ASP.NET Files\root\be9ddc15\a84d5058\App_Web_edit.aspx.b2d4184a.thgwih90.0.cs    Line: 196

i were clueless, but then i looked at App_Web_edit.aspx.b2d4184a.thgwih90.0.cs and found this:

Line 190:      public class views_skadeanmälan_edit_aspx : UKFS.Web.Views.ValidatedModelViewPage<Skadeanmälan>, System.Web.SessionState.IRequiresSessionState, System.Web.IHttpHandler {
Line 191:          
Line 192:          private static bool @__initialized;
Line 193:          
Line 194:          private static object @__fileDependencies;
Line 195:          
Line 196:          [System.Diagnostics.DebuggerNonUserCodeAttribute()]
Line 197:          public views_skadeanmälan_edit_aspx() {

of course, the generated class views_skadeanmälan_edit_aspx inheritates from my UKFS.Web.Views.ValidatedModelViewPage, and when it tries to instance it with the default construct.. so can you solve it?

Answer 1

You won't be able to constructor inject into ViewPages because the aspx compiler generates an empty ctor and as it derives from your base-class, your base-class must also have a empty ctor.

I'd look for property injection instead, otherwise try to accomplish the following:

• Find the place where viewpages are instantiated, and get the Autofact there to instantiate the page
• get the aspx compiler to not generate the empty ctor

I don't know how to do those things, so I'd aim for property injection instead