aws lambda call not populating body on POST

Question

Thanks to help from EVK on my previous Q (can use API GET but not API POST) I was able to resolve the problem of not being able to make an API POST request from an aws lambda in node, when I could hit the GET. The problem was not populating post_options.

Anyway, now I am able to successfully call the post but I cant get the body populated.

related documentation https://nodejs.org/api/http.html#http_http_request_options_callback

If you see my API POST call below.

 //// POST api/<controller>
      public string SapEaiCall([FromBody]string xmlFile)
        {
            string responseMsg = "Failed Import Active Directory User";

            if (string.IsNullOrEmpty(xmlFile))
            {
                responseMsg = "XML file is NULL";
            }

            if (responseMsg != "XML file is NULL")
            {
                xmlFile = RemoveFirstAndLastQuotes(xmlFile);

                if (!IsNewestVersionOfXMLFile(xmlFile))
                {
                    responseMsg = "Not latest version of file, update not performed";
                }
                else
                {
                    Business.PersonnelReplicate personnelReplicate = BusinessLogic.SynchronisePersonnel.BuildFromDataContractXml<Business.PersonnelReplicate>(xmlFile);
                    bool result = Service.Personnel.SynchroniseCache(personnelReplicate);

                    if (result)
                    {
                        responseMsg = "Success Import Sap Cache User";
                    }
                }
            }

            return "{\"response\" : \" " + responseMsg + " \" , \"isNewActiveDirectoryUser\" : \" false \"}";

        }

Every time I call it from the aws lambda, it returns responseMsg = "XML file is NULL";

Please see my example below:

    var querystring = require('querystring');
var https = require('https');
var fs = require('fs');

exports.handler = function(event, context) {

   const post_data = querystring.stringify({'msg': 'Hello World!'});

    // An object of options to indicate where to post to
    var post_options = {
        host: 'URL',
        protocol: 'https:',
        port: '443',
        path: '/api/SyncPersonnelViaAwsApi/SapEaiCall',
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
            'Content-Length': post_data.length
        }
    };

    //ignores SSL
   process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";
    var post_request = https.request(post_options, function(res) {
        var body = "";

        res.on('data', function(chunk)  {
            body += chunk;
        });

        res.on('end', function() {
            context.done(body);
        });

        res.on('error', function(e) {
            context.fail('error:' + e.message);
        });
    });

    // post the data
    post_request.write(post_data);
    post_request.end();
 console.log("posted data " +post_data); //returns posted data msg=Hello%20World!
};

So I have populated post data, and also tried populating the body. Still returns XML file is NULL

Does anyone please have any idea why?

Thanks

Answer 1

You are sending the following text in body:

msg=Hello%20World!

And you state that request content type is:

'Content-Type': 'application/json'

Does your body represents valid json? It doesn't. So that's first problem - content type stated in your request and actual data your send do not match each other.

Then let's look at:

public string SapEaiCall([FromBody]string xmlFile)

It basically says: look at the body of request and use binder appropriate for request content type to bind value of xmlFile parameter. Since request content type is "application/json" - binder expects body to contain one single json string, that is, body in such case should be (including quotes):

"Hello World!"

So if you pass that (for example via const post_data = JSON.stringify('Hello World!'); - it should work.

But then what if you want to pass more parameters in your body, not just xmlFile? Then you need to define a model, and I'd say even if you have just one parameter - it's better to do that. For example:

public class SapEaiCallParameters {
    public string XmlFile { get; set; }
}

// FromBody can be omitted in this case
public IHttpActionResult Post(SapEaiCallParameters parameters) {

}

And then you call it as you would expect, passing json:

const model = {xmlFile: 'Hello World!'};
const post_data = JSON.stringify(model);

Side note: don't do this:

return "{\"response\" : \" " + responseMsg + " \" , \"isNewActiveDirectoryUser\" : \" false \"}";

Instead, create another model, like this:

public class SapEaiCallResponse {
    public string Response { get; set; }
    public bool IsNewActiveDirectoryUser { get; set; }
}

And return it:

    public IHttpActionResult Post(SapEaiCallParameters parameters) {
        ...
        return Json(new SapEaiCallResponse {
            Response = responseMsg,
            IsNewActiveDirectoryUser = false,
        });
    }