IDictionary<string, object> to ExpandoObject extension method

As you know, the ExpandoObject class implements the IDictionary<string, object> interface, so if you have an ExpandoObject you can easily cast it to an IDictionary<string, object> but there’s no built-in way to easily do the reverse.

Luckily, I came across a very useful extension method today which converts an IDictionary<string, object> into an ExpandoObject, which you can then use dynamically in your code, sweet! :-)

With some small modifications, here’s the code I ended up with, with some comments thrown in for good measures:

   1: /// <summary>

   2: /// Extension method that turns a dictionary of string and object to an ExpandoObject

   3: /// </summary>

   4: public static ExpandoObject ToExpando(this IDictionary<string, object> dictionary)

   5: {

   6:     var expando = new ExpandoObject();

   7:     var expandoDic = (IDictionary<string, object>)expando;


   9:     // go through the items in the dictionary and copy over the key value pairs)

  10:     foreach (var kvp in dictionary)

  11:     {

  12:         // if the value can also be turned into an ExpandoObject, then do it!

  13:         if (kvp.Value is IDictionary<string, object>)

  14:         {

  15:             var expandoValue = ((IDictionary<string, object>)kvp.Value).ToExpando();

  16:             expandoDic.Add(kvp.Key, expandoValue);

  17:         }

  18:         else if (kvp.Value is ICollection)

  19:         {

  20:             // iterate through the collection and convert any strin-object dictionaries

  21:             // along the way into expando objects

  22:             var itemList = new List<object>();

  23:             foreach (var item in (ICollection)kvp.Value)

  24:             {

  25:                 if (item is IDictionary<string, object>)

  26:                 {

  27:                     var expandoItem = ((IDictionary<string, object>) item).ToExpando();

  28:                     itemList.Add(expandoItem);

  29:                 }

  30:                 else

  31:                 {

  32:                     itemList.Add(item);

  33:                 }

  34:             }


  36:             expandoDic.Add(kvp.Key, itemList);

  37:         }

  38:         else

  39:         {

  40:             expandoDic.Add(kvp);

  41:         }

  42:     }


  44:     return expando;

  45: }


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Yan Cui

I’m an AWS Serverless Hero and the author of Production-Ready Serverless. I have run production workload at scale in AWS for nearly 10 years and I have been an architect or principal engineer with a variety of industries ranging from banking, e-commerce, sports streaming to mobile gaming. I currently work as an independent consultant focused on AWS and serverless.

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