Within WCF services, there are many different return types that you can use in order to get data from different dependencies within a service. One problem, though, when working with WCF you might run into, is that WCF doesn’t support usage of a Dictionary as a return type. Although there are many reasons for this (which I will not go into now), but there are also different ways of dealing with this. All the examples I found online seemed like reasonable options, but I also had a different idea.

Since WCF allows for a List return type, why not convert a dictionary to a list, return it, and convert it back into a dictionary? Having two methods, one that converts from a dictionary to a list, and another that converts back, would make this very easy to do.

Below are two methods for doing just this!

Code Snippet
  1. private static string separationString = "!|!";
  3.     public static List<String> fromDictionaryToList(Dictionary<Int32, String> dictionaryToConvert)
  4.     {
  5.         List<String> returnList = new List<String>();
  7.         foreach (KeyValuePair<Int32, String> i in dictionaryToConvert)
  8.         {
  9.             String stringToAdd = i.Key.ToString() + separationString + i.Value.ToString();
  10.             returnList.Add(stringToAdd);
  11.         }
  13.         return returnList;
  14.     }
  16.     public static Dictionary<Int32, String> fromListToDictionary(List<String> listToConvert)
  17.     {
  18.         Dictionary<Int32, String> returnDictionary = new Dictionary<Int32, String>();
  19.         string[] separator = new string[] { separationString };
  21.         foreach (String i in listToConvert)
  22.         {
  23.             string[] convertedStrings = i.Split(separator, StringSplitOptions.None);
  24.             Int32 itemInt;
  25.             Int32.TryParse(convertedStrings[0].ToString(), out itemInt);
  26.             String itemString = convertedStrings[1].ToString();
  27.             returnDictionary.Add(itemInt, itemString);
  28.         }
  30.         return returnDictionary;
  31.     }

So, how do we test this? Pretty simple… just create a new dictionary with some values, send it through both, and debug to see what the values are. Here is an example of the pageload of an aspx form:

Code Snippet
  1. protected void Page_Load(object sender, EventArgs e)
  2.     {
  3.         Dictionary<Int32, String> dictionaryTest = new Dictionary<Int32, String>();
  5.         dictionaryTest.Add(1, "Clearly The First Dictionary Item");
  6.         dictionaryTest.Add(2, "The Second Dictionary Item");
  8.         List<String> convertedDictionary = fromDictionaryToList(dictionaryTest);
  10.         Dictionary<Int32, String> convertedList = fromListToDictionary(convertedDictionary);
  12.     }


So, once we setup a debug point, and run our project, it should stop at the end of the Page_load function. Once running, we can see that the values come through, no problem.



Although I implemented this with a string and integer, since Dictionary is a generic class, you can specify whatever types you need to implement. You will then need to modify the functions to support your desired data-type.