Question

I have a custom configuration section and i want to generate an xsd scheme using the xsd tool, however i get the following error :

Microsoft (R) Xml Schemas/DataTypes support utility
[Microsoft (R) .NET Framework, Version 4.0.30319.1]
Copyright (C) Microsoft Corporation. All rights reserved.
Error: There was an error processing 'C:\Development\XXX Application Framewo
rk\XXX.AppFramework\bin\Debug\XXX.AppFramework.dll'.
- There was an error reflecting type 'XXX.AppFramework.Configuration.AppFr
ameworkEnvironmentConfiguration'.
- You must implement a default accessor on System.Configuration.ConfigurationL
ockCollection because it inherits from ICollection.

However i do not implement ICollection on my section, it looks like this :

public class AppFrameworkEnvironmentConfiguration : ConfigurationElement
{
    [ConfigurationProperty("Name")]
    public string Name
    {
        get { return (string)this["Name"]; }
        set { this["Name"] = value; }
    }

    [ConfigurationProperty("Description")]
    public string Description
    {
        get { return (string)this["Description"]; }
        set { this["Description"] = value; }
    }

    [ConfigurationProperty("ApplicationName")]
    public string ApplicationName
    {
        get { return (string)this["ApplicationName"]; }
        set { this["ApplicationName"] = value; }
    }

    [ConfigurationProperty("DeploymentMode",DefaultValue=DeploymentMode.Local)]
    public DeploymentMode DeploymentMode
    {
        get { return (DeploymentMode)this["DeploymentMode"]; }
        set { this["DeploymentMode"] = value; }
    }


}

It doesnt look like ConfigurationElement implements ICollection so im not sure why i am getting this error ?

Having had a deep look through reflector to find when this error is thrown, im even more perplexed, first off my little test does indeed evaluate to false :

bool test = typeof(ICollection).IsAssignableFrom(typeof    (XXX.AppFramework.Configuration.AppFrameworkEnvironmentConfiguration));

In reflector the only place i can find it raise that exception is wrapped in this exact test, i have found it in System.Xml.Reflection.TypeScope.ImportTypeDesc and looks like this :

else if (typeof(ICollection).IsAssignableFrom(type))
{
    root = TypeKind.Collection;
    elementType = GetCollectionElementType(type, (memberInfo == null) ? null : (memberInfo.DeclaringType.FullName + "." + memberInfo.Name));
    none |= GetConstructorFlags(type, ref exception);
}

and then

private static Type GetCollectionElementType(Type type, string memberInfo)
{
return GetDefaultIndexer(type, memberInfo).PropertyType;
}

which calls

internal static PropertyInfo GetDefaultIndexer(Type type, string memberInfo)
{
if (typeof(IDictionary).IsAssignableFrom(type))
{
    if (memberInfo == null)
    {
        throw new NotSupportedException(Res.GetString("XmlUnsupportedIDictionary",     new     object[] { type.FullName }));
    }
    throw new NotSupportedException(Res.GetString("XmlUnsupportedIDictionaryDetails", new object[] { memberInfo, type.FullName }));
}
MemberInfo[] defaultMembers = type.GetDefaultMembers();
PropertyInfo info = null;
if ((defaultMembers != null) && (defaultMembers.Length > 0))
{
    for (Type type2 = type; type2 != null; type2 = type2.BaseType)
    {
        for (int i = 0; i < defaultMembers.Length; i++)
        {
            if (defaultMembers[i] is PropertyInfo)
            {
                PropertyInfo info2 = (PropertyInfo) defaultMembers[i];
                if ((info2.DeclaringType == type2) && info2.CanRead)
                {
                    ParameterInfo[] parameters = info2.GetGetMethod().GetParameters();
                    if ((parameters.Length == 1) && (parameters[0].ParameterType == typeof(int)))
                    {
                        info = info2;
                        break;
                    }
                }
            }
        }
        if (info != null)
        {
            break;
        }
    }
}
if (info == null)
{
    throw new InvalidOperationException(Res.GetString("XmlNoDefaultAccessors", new object[] { type.FullName })); **< HERE IS THE ERROR**
}
if (type.GetMethod("Add", new Type[] { info.PropertyType }) == null)
{
    throw new InvalidOperationException(Res.GetString("XmlNoAddMethod", new object[] { type.FullName, info.PropertyType, "ICollection" }));
}
return info;
}

I also tried adding a default parameterless constructor, no different ;-(
Any ideas ?

Answer 1

Can you try adding a default constructor, I have seen similar issues like this and adding an empty default constructor has fixed this for me in the past. Not sure why, but have been meaning to research it at some point.