How do I reflect over the members of dynamic object

Question

I need to get a dictionary of properties and their values from an object declared with the dynamic keyword in  NET 4  It seems using reflection for this will not work    Example   dynamic s   new ExpandoObject    s Path     Home   s Name    Home       How do I enumerate the Path and Name properties and get their values  IDictionary lt string  object gt  propertyValues

User · Accepted Answer

If the IDynamicMetaObjectProvider can provide the dynamic member names, you can get them. See GetMemberNames implementation in the apache licensed PCL library Dynamitey (which can be found in nuget), it works for ExpandoObjects and DynamicObjects that implement GetDynamicMemberNames and any other IDynamicMetaObjectProvider who provides a meta object with an implementation of GetDynamicMemberNames without custom testing beyond is IDynamicMetaObjectProvider.

After getting the member names it's a little more work to get the value the right way, but Impromptu does this but it's harder to point to just the interesting bits and have it make sense. Here's the documentation and it is equal or faster than reflection, however, unlikely to be faster than a dictionary lookup for expando, but it works for any object, expando, dynamic or original - you name it.

User · Answer

There are several scenarios to consider  First of all  you need to check the type of your object  You can simply call GetType   for this  If the type does not implement IDynamicMetaObjectProvider  then you can use reflection same as for any other object  Something like   var propertyInfo   test GetType   GetProperties      However  for IDynamicMetaObjectProvider implementations  the simple reflection doesn t work  Basically  you need to know more about this object  If it is ExpandoObject  which is one of the IDynamicMetaObjectProvider implementations   you can use the answer provided by itowlson  ExpandoObject stores its properties in a dictionary and you can simply cast your dynamic object to a dictionary    If it s DynamicObject  another IDynamicMetaObjectProvider implementation   then you need to use whatever methods this DynamicObject exposes  DynamicObject isn t required to actually  store  its list of properties anywhere  For example  it might do something like this  I m reusing an example from my blog post    public class SampleObject   DynamicObject       public override bool TryGetMember GetMemberBinder binder  out object result                result   binder Name          return true            In this case  whenever you try to access a property  with any given name   the object simply returns the name of the property as a string   dynamic obj   new SampleObject    Console WriteLine obj SampleProperty     Prints  SampleProperty     So  you don t have anything to reflect over - this object doesn t have any properties  and at the same time all valid property names will work   I d say for IDynamicMetaObjectProvider implementations  you need to filter on known implementations where you can get a list of properties  such as ExpandoObject  and ignore  or throw an exception  for the rest

User · Answer

In the case of ExpandoObject  the ExpandoObject class actually implements IDictionary lt string  object gt  for its properties  so the solution is as trivial as casting   IDictionary lt string  object gt  propertyValues    IDictionary lt string  object gt  s    Note that this will not work for general dynamic objects   In these cases you will need to drop down to the DLR via IDynamicMetaObjectProvider

User · Answer

Requires Newtonsoft Json Net  A little late  but I came up with this   It gives you just the keys and then you can use those on the dynamic   public List lt string gt  GetPropertyKeysForDynamic dynamic dynamicToGetPropertiesFor        JObject attributesAsJObject   dynamicToGetPropertiesFor      Dictionary lt string  object gt  values   attributesAsJObject ToObject lt Dictionary lt string  object gt  gt         List lt string gt  toReturn   new List lt string gt         foreach  string key in values Keys                toReturn Add key                             return toReturn      Then you simply foreach like this   foreach string propertyName in GetPropertyKeysForDynamic dynamicToGetPropertiesFor         dynamic object string propertyValue   dynamicToGetPropertiesFor propertyName          And     dynamicToGetPropertiesFor propertyName     Your Value      Or an object value     Choosing to get the value as a string or some other object  or do another dynamic and use the lookup again

[c#] How do I reflect over the members of dynamic object?

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