convert C# Enum to Json array to bind knockout options

Question

How to convert Asp.NET Enum to Json array, so it can be used for knockout options binding?

Options I see: is to create some custom enum extender (create method ConvertToJson that converts enum to Json) and write

<script>
    var myTypeEnum = @ConvertToJson(typeof(ClientTypeEnum)) ; 
</script>

and then I can use

 <select data-bind="options: myTypeEnum, ....></select>

But I believe there are better options, so I do need to write ConverToJson method by myself?

Hmm.. I believe need both. I need to save updates values to DB (so probably Ids are necessary here) and show user names. — renathy, Nov 25 '13 at 12:28

score 1 · Answer 1 · edited May 23 '17 at 12:25

1

I realise that this is using Web API rather than Razor in a view, but we've set up Json.Net to convert Enums to strings:

var formatters = GlobalConfiguration.Configuration.Formatters;
var jsonFormatter = formatters.JsonFormatter;
var settings = jsonFormatter.SerializerSettings;
settings.Converters.Add(new StringEnumConverter());

With this set up, it just deals with serialising and deserialising enums to and from the string representation. It appears that you can set it up for Asp.Net.

edited May 23 '17 at 12:25

Community

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1

answered Nov 25 '13 at 15:04

Paul Manzotti

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I need to have json array, I do not understand how this is related to arrays? – renathy Nov 26 '13 at 07:44
You would need to return an array with all the enum values in it, and the serialiser will turn them into the string representation for you, so you would get a list of the enum strings. Any other objects that have a property of that enum type will also have their value returned as the string representation, so you would map the selected enum value by a simple string comparison. – Paul Manzotti Nov 26 '13 at 08:53
What if I do not need enum values, but descriptions (defined using anotations)? – renathy Nov 26 '13 at 12:44

gbs · Answer 2 · 2013-11-26T16:24:51.590

Extending the HTMLHelper:

    public static MvcHtmlString EnumToJson(this System.Web.Mvc.HtmlHelper helper) where E : struct, IConvertible
    {
        var values = from E e in Enum.GetValues(typeof(E)) select String.Format(@"{{""Val"": {0:d}, ""Text"": ""{1}""}}", e, e.ToString());
        return MvcHtmlString.Create("[" + String.Join(",", values.ToArray()) + "]");
    }

In javascript:

    var accessLevels = JSON.parse('@(Html.EnumToJson<MyEnum>())');

score 0 · Answer 3 · answered Nov 25 '13 at 12:33

Not totally sure but you can try something like this:

// here is the string you pass to the client, a list separated by commas like Aaa, Bbb, Ccc
string result = Enum.GetNames(typeof(ClientTypeEnum)).Aggregate((s1, s2) => string.Format("{0},{1}", s1, s2)); 

// then a client sends a string to the server and you parse it like this
 ClientTypeEnum cte = (ClientTypeEnum) Enum.Parse(typeof(ClientTypeEnum), "EnumStr", true);

Henric Rosvall · Answer 4 · 2016-05-03T08:44:13.090

The previous answer about extending the Html helper works great, but the <T> was missing (or in that case <E>). It should be:

        
    public static MvcHtmlString EnumToJson<T>(this System.Web.Mvc.HtmlHelper helper) where T : struct, IConvertible
    {

        var values = from T e in Enum.GetValues(typeof(T)) select String.Format(@"{{""Value"": {0:d}, ""Text"": ""{1}""}}", e, e.ToString());
        return MvcHtmlString.Create("[" + String.Join(",", values.ToArray()) + "]");

    }


var accessLevels = JSON.parse('@(Html.EnumToJson())');

(I would have just added it as a comment to the original answer if I could, but my account needs to have 50 points to be able to comment o_O)

convert C# Enum to Json array to bind knockout options

4 Answers4