Is there a utility to serialise an object as HTTP content type "application/x-www-form-urlencoded"? - http

Question

I've never had to do this before, because it's always only been an actual form that I've posted as that content type, but recently I had to post three variables like that, and I resorted to a sordid concatenation with & and =:
var content = new StringContent("grant_type=password&username=" + username + "&password=" + password.ToClearString(), Encoding.UTF8,
"application/x-www-form-urlencoded");
I'm sure there must be a utility method that would do that, and do it better, with any necessary encoding. What would that be?

Answer 1

If this is a POCO and just using the Newtonsoft library, you can use this as well:
public static class FormUrlEncodedContentExtension
{
public static FormUrlEncodedContent ToFormUrlEncodedContent(this object obj)
{
var json = Newtonsoft.Json.JsonConvert.SerializeObject(obj);
var keyValues = JsonConvert.DeserializeObject<Dictionary<string, string>>(json);
var content = new FormUrlEncodedContent(keyValues);
return content;
}
}
And a sample usage would be:
var myObject = new MyObject {Grant_Type = "TypeA", Username = "Hello", Password = "World"};
var request = new HttpRequestMessage(HttpMethod.Post, "/path/to/post/to")
{
Content = myObject.ToFormUrlEncodedContent()
};
var client = new HttpClient {BaseAddress = new Uri("http://www.mywebsite.com")};
var response = await client.SendAsync(request);

Answer 2

Use reflection to get the property names and values and then use them to create a System.Net.Http.FormUrlEncodedContent
public static class FormUrlEncodedContentExtension {
public static FormUrlEncodedContent ToFormUrlEncodedContent(this object obj) {
var nameValueCollection = obj.GetType()
.GetProperties()
.ToDictionary(p => p.Name, p => (p.GetValue(obj) ?? "").ToString());
var content = new FormUrlEncodedContent(nameValueCollection);
return content;
}
}
From there it is a simple matter of calling the extension method on an object to convert it to a FormUrlEncodedContent
var model = new MyModel {
grant_type = "...",
username = "...",
password = "..."
};
var content = model.ToFormUrlEncodedContent();

Answer 3

You should be able to use string interpolation for that. Something like:
var content = new StringContent($"grant_type=password&username={username}&password={password}", Encoding.UTF8, "application/x-www-form-urlencoded");
Or wrap this inside a helper/factory method:
public static class StringContentFactory
{
public static StringContent Build(string username, string password)
{
return new StringContent($"grant_type=password&username={username}&password={password}", Encoding.UTF8, "application/x-www-form-urlencoded");
}
}