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I have been using the KendoDynamicLinq library for years on this project with no problems. I started to use VS 2017 Community Edition instead of VS 2013 on this same project/code and if I run the project with VS 2017 I get this exception: System.Reflection.TargetException: 'Non-static method requires a target.'

But if I run it with VS 2013, no problem, no exception and all is working.

I have been wracking my head around this but I cannot seem to find the answer. Any help or direction to point me to would be appreciate it.

private static MethodInfo GetMethod(string methodName, MethodInfo methodTypes, int genericArgumentsCount)
        {
            var methods = from method in typeof(Queryable).GetMethods(BindingFlags.Public | BindingFlags.Static)
                          let parameters = method.GetParameters()
                          let genericArguments = method.GetGenericArguments()
                          where method.Name == methodName &&
                            genericArguments.Length == genericArgumentsCount &&
                            parameters.Select(p => p.ParameterType).SequenceEqual((Type[])methodTypes.Invoke(null, genericArguments))
                          select method;
            return methods.FirstOrDefault();
        }

The line that is throwing is this:

parameters.Select(p => p.ParameterType).SequenceEqual((Type[])methodTypes.Invoke(null, genericArguments))

Do you see anything here that can work with VS2013 but not in VS 2017. No changes to the solution or the target framework.

code_dredd
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emadev
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    The problem is actually in the caller of GetMethod who passed methodTypes. They were supposed to pick a static method and picked an instance method instead. Just off the top of my head, there was change in the C# compiler that changed certain kinds of lambda expressions from static methods to instance methods on a singleton closure class in that time frame. – Mike Zboray Feb 16 '18 at 00:00
  • Thank you, I'll look into it, hard to say, this library receives a IQuarable collection and applies filters and aggregators from a UI Kendo grid. In this case it is a sum of a certain field. Not sure there what is the method and how to intercept it. I'll investigate more an post findings. – emadev Feb 16 '18 at 03:49
  • If you are recompiling this library from the source code in VS 2017 then it makes sense. The underlying change in the C# compiler causing the issue is described [here](https://stackoverflow.com/questions/30897647/delegate-caching-behavior-changes-in-roslyn). – Mike Zboray Feb 16 '18 at 04:05

1 Answers1

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Thank you mike z for pointing me to right direction. I am now checking if the methodTypes passed in is static or not and if it is static I am now passing in null as a target object. But if it is not static, then I create an instance of the object and pass that instead. Here is the new calling code:

var m = ((Func<Type, Type[]>)this.GetType().GetMethod("SumAvgFunc", BindingFlags.Static | BindingFlags.NonPublic)
                        .MakeGenericMethod(proptype).Invoke(null, null)).GetMethodInfo();
                    object obj = null;
                    if (!m.IsStatic)
                    {
                        obj = Activator.CreateInstance(m.DeclaringType);
                    }
                    return GetMethod(aggregate, m, 1, obj).MakeGenericMethod(type);

So I added a parameter to the GetMethod() method that takes an object which will be null if the method is static otherwise it will be an instance of the class whom method is a member. Here is GetMethod :

private static MethodInfo GetMethod(string methodName, MethodInfo methodTypes, int genericArgumentsCount, object obj)
        {
            var methods = from method in typeof(Queryable).GetMethods(BindingFlags.Public | BindingFlags.Static)
                          let parameters = method.GetParameters()
                          let genericArguments = method.GetGenericArguments()
                          where method.Name == methodName &&
                            genericArguments.Length == genericArgumentsCount &&
                            parameters.Select(p => p.ParameterType).SequenceEqual((Type[])methodTypes.Invoke(obj, genericArguments))
                          select method;
            return methods.FirstOrDefault();
        }

Now all works just fine as it was working before with VS 2013. Thank you mike z

emadev
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