In c# convert anonymous type into key/value array?

I have the following anonymous type:

new {data1 = "test1", data2 = "sam", data3 = "bob"}

I need a method that will take this in, and output key value pairs in an array or dictionary.

My goal is to use this as post data in an HttpRequest so i will eventually concatenate in into the following string:

"data1=test1&data2=sam&data3=bob"

This takes just a tiny bit of reflection to accomplish.

var a = new { data1 = "test1", data2 = "sam", data3 = "bob" };
var type = a.GetType();
var props = type.GetProperties();
var pairs = props.Select(x => x.Name + "=" + x.GetValue(a, null)).ToArray();
var result = string.Join("&", pairs);

If you are using .NET 3.5 SP1 or .NET 4, you can (ab)use RouteValueDictionary for this. It implements IDictionary<string, object> and has a constructor that accepts object and converts properties to key-value pairs.

It would then be trivial to loop through the keys and values to build your query string.

Here is how they do it in RouteValueDictionary:

  private void AddValues(object values)
    {
        if (values != null)
        {
            foreach (PropertyDescriptor descriptor in TypeDescriptor.GetProperties(values))
            {
                object obj2 = descriptor.GetValue(values);
                this.Add(descriptor.Name, obj2);
            }
        }
    }

Full Source is here: http://pastebin.com/c1gQpBMG

There is a built-in method of converting anonymous objects to dictionaries:

HtmlHelper.AnonymousObjectToHtmlAttributes(yourObj)

It also returns RouteValueDictionary. Note that it's static

using Newtonsoft.Json;
var data = new {data1 = "test1", data2 = "sam", data3 = "bob"};
var encodedData = new FormUrlEncodedContent(JsonConvert.DeserializeObject<Dictionary<string, string>>(JsonConvert.SerializeObject(data))

It is too late but anyway I would add this for a more robust solution. The ones I see here have some kind of problems (like they wouldn't work right with say DateTime). For that reason, I suggest first converting to a json (Newtonsoft Json.Net):

var data = new {data1 = "test1", data2 = "sam", data3 = "bob"};

var result = string.Join("&",
			JsonConvert.DeserializeObject<Dictionary<string, string>>(
			JsonConvert.SerializeObject(data))
			.Select(x => $"{x.Key}={x.Value}")
		);

@kbrimington's solution makes a nice extension method - my my case returning a HtmlString

    public static System.Web.HtmlString ToHTMLAttributeString(this Object attributes)
    {
        var props = attributes.GetType().GetProperties();
        var pairs = props.Select(x => string.Format(@"{0}=""{1}""",x.Name,x.GetValue(attributes, null))).ToArray();
        return new HtmlString(string.Join(" ", pairs));
    }

I'm using it to drop arbitrary attributes into a Razor MVC view. I started with code using RouteValueDictionary and looping on the results but this is much neater.

I did something like this:

public class ObjectDictionary : Dictionary<string, object>
{
    /// <summary>
    /// Construct.
    /// </summary>
    /// <param name="a_source">Source object.</param>
    public ObjectDictionary(object a_source)
        : base(ParseObject(a_source))
    {
        
    }

    /// <summary>
    /// Create a dictionary from the given object (<paramref name="a_source"/>).
    /// </summary>
    /// <param name="a_source">Source object.</param>
    /// <returns>Created dictionary.</returns>
    /// <exception cref="ArgumentNullException">Thrown if <paramref name="a_source"/> is null.</exception>
    private static IDictionary<String, Object> ParseObject(object a_source)
    {
        #region Argument Validation

        if (a_source == null)
            throw new ArgumentNullException("a_source");

        #endregion

        var type = a_source.GetType();
        var props = type.GetProperties();

        return props.ToDictionary(x => x.Name, x => x.GetValue(a_source, null));
    }
}

Building on @GWB's suggestion of using a RouteValueDictionary, I wrote this recursive function to support nested anonymous types, prefixing those nested parameters by their parents' keys.

public static string EncodeHtmlRequestBody(object data, string parent = null) {
    var keyValuePairs = new List<string>();
    var dict = new RouteValueDictionary(data);

    foreach (var pair in dict) {
        string key = parent == null ? pair.Key : parent + "." + pair.Key;
        var type = pair.Value.GetType();
        if (type.IsPrimitive || type == typeof(decimal) || type == typeof(string)) {
            keyValuePairs.Add(key + "=" + Uri.EscapeDataString((string)pair.Value).Replace("%20", "+"));
        } else {
            keyValuePairs.Add(EncodeHtmlRequestBody(pair.Value, key));
        }
    }

    return String.Join("&", keyValuePairs);
}

Example usage:

var data = new {
    apiOperation = "AUTHORIZE",
    order = new {
        id = "order123",
        amount = "101.00",
        currency = "AUD"
    },
    transaction = new {
        id = "transaction123"
    },
    sourceOfFunds = new {
        type = "CARD",
        provided = new {
            card = new {
                expiry = new {
                    month = "1",
                    year = "20"
                },
                nameOnCard = "John Smith",
                number = "4444333322221111",
                securityCode = "123"
            }
        }
    }
};

string encodedData = EncodeHtmlRequestBody(data);

encodedData becomes:

"apiOperation=AUTHORIZE&order.id=order123&order.amount=101.00&order.currency=AUD&transaction.id=transaction123&sourceOfFunds.type=CARD&sourceOfFunds.provided.card.expiry.month=1&sourceOfFunds.provided.card.expiry.year=20&sourceOfFunds.provided.card.nameOnCard=John+Smith&sourceOfFunds.provided.card.number=4444333322221111&sourceOfFunds.provided.card.securityCode=123"

Hope this helps someone else in a similar situation.

Edit: As DrewG pointed out, this doesn't support arrays. To properly implement support for arbitrarily nested arrays with anonymous types would be non-trivial, and as none of the APIs I've used have accepted arrays either (I'm not sure there's even a standardised way of serialising them with form encoding), I'll leave that to you folks if you need to support them.