Question

I have a really weird issue that I can’t figure out with comparing objects on IIS 7. We are in the process of deploying our old IIS 6 based ASP.NET application on IIS 7, however we have this equality comparison issue that we can’t seem to figure out.

Let me start out by saying that I have the same assemblies and code running both on IIS 6 and IIS 7, however the comparison of the objects is differing with the same code both on IIS 6 and IIS 7. Here is an example of what my object looks like:

class Country : EntityBase {     public int CountryID { get; set; }     public string Name { get; set; }      public override bool Equals(object obj) {         if (obj == null || !(obj is Country))             return false;          Country c = (Country)obj;         return CountryID == c.CountryID;     }      public override int GetHashCode() {         return CountryID.GetHashCode();     } } 

I have the following code in an ASPX page both on IIS 6 and IIS 7:

<% foreach(var country in proposalCountries) { %> <%= country.Country.CountryID %> <%= country.Country.CountryID.GetHashCode() %> <%= country.Country.GetHashCode() %>  <%= proposalCountryServices.Count(c => c.Country == country.Country) %> <%= proposalCountryServices.Count(c => (c.Country != null && country.Country != null) && c.Country.Equals(country.Country)) %>) <%= proposalCountryServices.Count(c => Object.Equals(c.Country, country.Country)) %> <% } %> 

Here are my results:

IIS 6:

100 <-- CountryID 100 <-- CountryID Hash Code 100 <-- Country Hash Code  1 <-- Something Found 1 <-- Something Found 1 <-- Something Found 

IIS 7:

100 <-- CountryID 100 <-- CountryID Hash Code 100 <-- Country Hash Code  0 <-- Nothing Found 1 <-- Something Found 1 <-- Something Found 

Is there a difference between .NET 3.5 SP1 on Windows 2003 vs Windows 2008? I am really at a loss of what the problem could be. Has anybody experienced a similar issue?

Update 1:

To answer Jon’s question. The two collections are loaded using NHibernate. But I feel I should reiterate that both IIS 6 and IIS 7 are using the exact same build of the application, so unless NHibernate or DynamicProxy2 is changing how things are loaded based on Windows 2003 or Windows 2007, which I haven’t been able to find anything about on Google, I don’t know what to make of it.

This is also a system wide issue of whenever I am comparing two of my entity objects. So it could have something to do with the DynamicProxy2 wrapper, but both objects are Country objects and given the overrides I have created everything should work the same in IIS 6 and IIS 7.

Update 2:

This appears to be a DynamicProxy2 or NHibernate issue. Because I tried the following code:

<%     var c1 = new ICost.Business.Entities.Country {         CountryID = 100     };     var c2 = new ICost.Business.Entities.Country {         CountryID = 100     }; %> <%= c1.CountryID == c2.CountryID %> <%= c1.GetHashCode() == c2.GetHashCode() %> <%= c1.Equals(c2) %> <%= Object.Equals(c1, c2) %> <%= c1 == c2 %> 

And for both IIS 6 and IIS 7 the result was, true, true, true, true, false. See my answer below for what I did to solve this.

Update 3:

This also might have had something to do with it: Looks like you forgot to register the http module with Windsor Castle with IIS7

Answer 1

This is the solution that worked for me:

public static bool operator ==(BaseEntity a, BaseEntity b) {     return Object.Equals(a, b); }  public static bool operator !=(BaseEntity a, BaseEntity b) {     return !Object.Equals(a, b); } 

Apparently NHibernate or DynamicProxy was doing some kind of magic under Windows 2003 to get the ‘==’ operator to work with out the operator being overloaded.