Marketo rest Api create lead - api

Question

I have a question about this create/Update leads API, http://developers.marketo.com/documentation/rest/createupdate-leads/.
There is no sample code for C# or JAVA. Only ruby available. So I have to try it by myself. But I always get null return from the response.
Here is my code:
private async Task<CreateLeadResponseResult> CreateLead(string token)
{
string url = String.Format(marketoInstanceAddress+"/rest/v1/leads.json?access_token={0}", token);
var fullUri = new Uri(url, UriKind.Absolute);
CreateLeadResponseResult createLeadResponse = new CreateLeadResponseResult();
CreateLeadInput input = new CreateLeadInput { email = "123#123.com", lastName = "Lee", firstName = "testtesttest", postCode = "00000" };
CreateLeadInput input2 = new CreateLeadInput { email = "321#gagaga.com", lastName = "Lio", firstName = "ttttttt", postCode = "00000" };
List<CreateLeadInput> inputList = new List<CreateLeadInput>();
inputList.Add(input);
inputList.Add(input2);
CreateLeadRequest createLeadRequest = new CreateLeadRequest() { input = inputList };
JavaScriptSerializer createJsonString = new JavaScriptSerializer();
string inputJsonString = createJsonString.Serialize(createLeadRequest);
using (var client = new HttpClient())
{
HttpResponseMessage response = await client.PostAsJsonAsync(fullUri.OriginalString, inputJsonString).ConfigureAwait(false);
// I can see the JSON string is in the message body in debugging mode.
if (response.IsSuccessStatusCode)
{
createLeadResponse = await response.Content.ReadAsAsync<CreateLeadResponseResult>();
}
else
{
if (response.StatusCode == HttpStatusCode.Forbidden)
throw new AuthenticationException("Invalid username/password combination.");
else
throw new ApplicationException("Not able to get token");
}
}
return createLeadResponse;}
//get null here.
Thank you.
-C.

Answer 1

The best way to debug this is to capture the exact URL, parameters and JSON that are submitted by your app and try submitting those manually via a tool like Postman (Chrome plug-in) or SOAP UI. Then you see the exact error message, which you can look up here: http://developers.marketo.com/documentation/rest/error-codes/. Based on that you can update your code. I don't know much about Java, but this is how I got my Python code to work.

Answer 2

Your example code was really helpful in getting my own implementation off the ground. Thanks!
After playing with it for a bit, I realized that the JavaScriptSerializer step is unnecessary since PostAsJsonAsync automatically serializes whatever object you pass to it. The double serialization prevents Marketo's API from processing the input.
Also, I agree with Jep that Postman is super helpful. But in the case of this error, Postman was working fine (using the contents of inputJsonString) but my C# code still didn't work properly. So I temporarily modified the code to return a dynamic object instead of a CreateLeadResponseResult. In debugging mode this allowed me to see fields that were discarded because they didn't fit the CreateLeadResponseResult type, which led me to the solution above.