Web API complex input parameter is null

I do maintain a ASP.NET WebAPI 2.0 service that was running smoothly for quite some time on our production server, until one day an existing client of our service reported that they are getting "invalid request" response from our service and that behavior is random. So we checked our logs and found that request object we received from them were actually null and thus the error they got. Till this point our controller action looked like below: 

To diagnose this issue we added logs to check raw request received by us and that confirmed two things: 

1. First request received by was fine but every subsequent same request was landing in our action as null 

2. Raw request content and headers were similar for both successful and failed requests

Below is code that I used to log raw request content:

To sort out the issue we changed our action slightly. Now instead of letting framework to do model binding for us, we started doing it manually as shown in below snippet: 

Here we are reading request content as string and then converting it to our expected object using newtonsoft json converter. Hopefully this will help you to save some of your time.

jQuery dynamic validation error messages

I am not a champ at asp.net mvc and found myself struggling with a task that at first I thought will be trivial, below is how I got through it :)

I wrote a custom validation attribute and needed to show validation messages as per values entered. Below is stripped down version of what I ended up doing:

Below lines add validation attribute named checkagainstmaxsumvalue that checks values of two fields and decides error messages dynamically

jQuery.validator.unobtrusive.adapters.add("checkagainstmaxsumvalue", ["dependentproperty1", "dependentproperty2"], function (options) {

    options.rules['checkagainstmaxsumvalue'] = {

        prop1: options.params['dependentproperty1'],

        prop2: options.params['dependentproperty2']

    };

});

jQuery.validator.addMethod("checkagainstmaxsumvalue", function (value, element, params) {

        var result = true;

        var prop1 = parseInt($('#' + params['prop1']).val(), 10);

        var prop2 = parseInt($('#' + params['prop2']).val(), 10);

        var errMsg = getErrorMessage(prop1, prop2);

        if (errMsg) {

            result = false;

        }

        return result;

    }, function (params, element) {

        var prop1 = parseInt($('#' + params['prop1']).val(), 10);

        var prop2 = parseInt($('#' + params['prop2']).val(), 10);

        return getErrorMessage(prop1, prop2);

    }

);

//Validation logic here, returns error message if validation fails 

//and empty string if success

function getErrorMessage(prop1, prop2) {

    var errMsg = "";

    if (prop1 < 20 && prop2 < 20) {

        errMsg = "Either of prop1 and prop2 should be greater than 20";

    } else if (prop1 + prop2 > 30) {

        errMsg = "Sum of prop1 and prop2 should be less than equal to 30";

    }

    return errMsg;

}

This all I did after reading below answer at every developer's life saver site SO :)
http://stackoverflow.com/questions/13352626/dynamic-jquery-validate-error-messages-with-addmethod-based-on-the-element#answer-13352987

This worked perfectly fine in my case but still there is concern that validation logic executes twice, once for deciding message and once for actual verification. This sounds a bit overkill but till now I didn't have a better option.