How do i convert a dynamic dictionary values to list?

Question

I have the below code:

List<Type> p1 = new List<Type>();
p1.Add(typeof(int));
p1.Add(typeof(string));
dynamic genericDic = typeof(Dictionary<, >);
dynamic specificDic1 = genericDic.MakeGenericType(p1.ToArray());
dynamic dic1 = Activator.CreateInstance(specificDic1);
dic1.Add(1, "John");
dic1.Add(2, "Smith");
dynamic genericLst = typeof(List<>);
dynamic specificLst = genericLst.MakeGenericType(typeof(string));
dynamic list = Activator.CreateInstance(specificLst);
list.AddRange(dic1.Values.ToList());

When i try to perform the list.AddRange(dic1.Values.ToList()); i get the following exception

Public member 'ToList' on type 'ValueCollection' not found.

Stack trace:

   at Microsoft.VisualBasic.CompilerServices.Symbols.Container.GetMembers(String& MemberName, Boolean ReportErrors)
   at Microsoft.VisualBasic.CompilerServices.NewLateBinding.ObjectLateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
   at Microsoft.VisualBasic.CompilerServices.NewLateBinding.LateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
   at StyleResearch.DataManagement.DataStream.Business.MonthEndProcess.ConverToLegacyStructureInMemory(List`1 marketDataTypeIds, String tableName, Int32 placeHolderValue) in C:\Style Research\Work\SRDM\trunk\StyleResearch.DataManagement.DataStream.Business\MonthEndProcess.vb:line 1850
   at StyleResearch.DataManagement.DataStream.UI.DDLMonthEndProcess._Lambda$__6(LegacyStructureDetail legacy) in C:\Style Research\Work\SRDM\trunk\StyleResearch.DataManagement.DataStream.UI\DDLMonthEndProcess.vb:line 1198
   at System.Threading.Tasks.Parallel.<>c__DisplayClass2d`2.<ForEachWorker>b__23(Int32 i)
   at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.<ForWorker>b__c()

NOTE: I have converted by VB.NET sample to C# but the stack trace is from the VB.NET project

When i do the below it works absolutely fine:

Dictionary<int, string> dic = new Dictionary<int, string>();
dic.Add(1, "John");
dic.Add(2, "Smith");
List<string> lst = new List<string>();
lst.AddRange(dic.Values.ToList());

Solution 1

Just cast it:

list.AddRange(((IEnumerable<string>)dic1.Values).ToList());

Also, you can go via dynamic again:

list.AddRange((dynamic)dic1.Values));

Solution 2

ToList<T>() is an extension method to IEnumerable<T>. But your dic1.Values is of dynamic type not IENumerable<string> so .Net can not find and use this extension method. You can try just simple foreach:

foreach (var value in dic1.Values)
  list.Add(value)

Comments

[Rajesh]

Thanks for the reply, but I do know that approach.Keen to know why it fails when i create objects using reflection and not when doing it normally.

[Nikolay]

As i said that happens because of dynamic type and extension method (ToList). Extension methods are not supported for dynamics (stackoverflow.com/questions/5311465/…)

[Rajesh]

When i use the above code i get this exception: Public member 'Cast' on type 'ValueCollection' not found.

[Dave Bish]

None of those work: 'System.Collections.Generic.Dictionary<int,string>.ValueColl‌​ection' does not contain a definition for 'Cast'

[abatishchev]

@Rajesh: Then try System.Linq.Enumerable.Cast<string>(input)

[Dave Bish]

Also - this is worse than casting the whole collection to IEnumerable<string> - as it will attempt to cast each element in the collection to 'string' - not cast the whole collection to an Enumerable type.

[Nikolay]

As i understand the idea behind using dynamics and reflections is that you dont know type of elements in list at compile time (IEnumerable<string>) so you can not just cast to it at compile time. Overwise you can just use types list without reflection and dynamics

[Dave Bish]

Agreed - but he's already declaring the type above - so, in this instance it's known.