Cassandra : map map<text, text> datatype of UDT to SortedDictionary in .Net

Question

I am using cassandra DB for .Net. I have created a datatype dictionary_type_property map<text,text> inside user defined datatype, but facing problem while converting this datatype value to .Net dictionary type using udtMap.

.Map(s => s.MyDictionaryTypeProperty, "dictionary_type_property");

dictionary type property is:

public SortedDictionary<string, string> MyDictionaryTypeProperty { get; set; }

Here I am getting the below exception: "No converter is available from Type System.Collections.Generic.IDictionary2[System.String,System.String] is not convertible to type System.Collections.Generic.SortedDictionary2[System.String,System.String]"

Appreciate your help.

Answer 1

Well, as the error says, you are trying to convert an IDictionary variable to SortedDictionary. However, IDictionary does not inherit from SortedDictionary, it's the other way around. I suggest you to read about inheritance, if you never heard about.

What I can suggest you, is to change

public SortedDictionary<string, string> MyDictionaryTypeProperty { get; set; }

to

public IDictionary<string, string> MyDictionaryTypeProperty { get; set; }

so this way,the method will try to "fit" an IDictionary value into a variable with the same type.

.Map(s => s.MyDictionaryTypeProperty, "dictionary_type_property");

if later you want to try to use this variable as a SortedDictionary, you might try using a cast (SortedDictionary) MyDictionaryTypeProperty

or

    SortedDictionary<string, string> sortedDictionary = new SortedDictionary<string, string>(MyDictionaryTypeProperty);