I'd appreciate it if anyone had any tips for this.

I have created a simple block for purposes of calculation, using information entered in the block data in the Optimizely CMS edit mode. The idea is that the user enters their information, the calculator form submits on click and the viewmodel is updated with the results of the calculation.

The problem is that while this works:

public override ActionResult Index(ViljahintalaskuriBlock currentBlock)
        {
            var model = new ViljahintalaskuriViewModel()
            {
                ViljahintalaskuriBlock = currentBlock
            };

            // ReSharper disable once Mvc.PartialViewNotResolved
            return PartialView("Viljahintalaskuri", model);
        }

This doesn't:

public ActionResult CalculateData([FromBody] GrainPriceCalculationPostbackDataDTO data)
        {
            // updating model with new values from the form data

            return PartialView("Viljahintalaskuri", model);
        }

The methods are in the same controller, and the latter one returns ONLY the partial view to the page instead of it embedded on the site like when calling the index. I realize this is because of how the CMS calls these controllers to render blocks/pages etc.

What should I do to have my method update the model for that partial view in place and not return ONLY the updated partial view to the browser?