C# – Ricardo Covo

Financial Functions in .Net (C#)

I recently worked on a project where I had to perform financial calculations. The main project requirements where provided on an Excel and because of the sensitivity of the calculations(mortgage payments), I had to keep within 1cent accuracy.

After reviewing the needed calculations, my main issue was the NPV (Net Present Value); although I am familiar with the formula and applications of NPV, I was not sure of the exact implementation in Excel.

So, I jumped to Google to see if there was any implementations and found the Excel Financial Functions for .Net: “… a .NET library that provides the full set of financial functions from Excel.”.

Great! BUT. The library is actually implemented in F# and only the source code is provided, no compiled version…. No problem, since all .Net languages compile into IL (Intermediate Language), all I needed to do was to compile the F# project and then reference it on my C# one.

After I add ed the Financial.dll reference to my project (compiled version included in the provided source code), I am ready to use it on my code, however, note that the following reference is required:

using

System.Numeric;

With the reference in place, I can now use the NPV function as follow:

Comparing the signature of the NPV function on Financial.dll to excel, we can see they are virtually the same:

And even though I have shown mainly the NPV usage, this library contains implementation pretty much all financial functions in Excel (Complete List).

There you have it; if you ever have a project where you need to use Excel functions, you can refer t the Excel Financial Functions for .Net library; you can use the compiled library provided on this example, but I recommend reviewing the library page regularly to check for updates.

Hope this helps!

ASP MVC3 – Editing records with jQueryUI Dialogs and AjaxForms – Razor Version

This post is in response to the several requests I’ve gotten to provide a Razor version of a sample solution I provided a few months ago on Editing records with jQueryUI Dialogs and AjaxForms, which was originally posted using aspx views. If you haven’t read it or seen the video, please take a look at it first; as most of the concepts will remain the same. .

So this solution is practically unchanged compared to the original, however I did I introduced 2 improvements (which could also apply to the aspx version).

I realized after I did my original post that I was able to get data on the handler function from the ajax form; so I am no longer looking into the response div for my data (which was kind of a hack). Instead I am now using it properly by receiving the data directly.
I use a JsonStandardResponse, which I have been using in my projects succesfully and make things a bit easier. (See my previous post: Json Standard Responses for your Ajax Calls). So the controller action was changed to return JsonResult instead of a regular ActionResult with Content.

Here are the details of the change in the controller:

[HttpPost]
public JsonResult Edit(CarModel model) {
if (ModelState.IsValid)
{
CarModel car = CarRepository.GetCars().Where(c => c.Id == model.Id).FirstOrDefault();
car.Name = model.Name;
car.Description = model.Description;
return Json(JsonResponseFactory.SuccessResponse(car),JsonRequestBehavior.DenyGet);
}
else {
return Json(JsonResponseFactory.ErrorResponse("Please review your form"), 
            JsonRequestBehavior.DenyGet);
}
}

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ASP.Net MVC: Using Json Standard Responses for your Ajax Calls

For the past couple of years, after we started our move towards ASP.Net MVC, we have been using more and more ajax to enrich our user interface and we love it.

At the begining we use to send our responses as simple strings (true/false) or very customized Json responses. However, for the past year or so we’ve been using Standard Json Responses and it has been working great. I’ve passed this idea to a couple of friends and everyone seems to like it so here it is.

Objective & Advantages

The objective will be to have standard Json Responses to our AJAX calls that we can easily re-use accross our application, independent of what action or what objects we are working with… And by having and standard responses, we can have a standard way to handle them.

Download the Code
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ASP MVC – Delete confirmation with Ajax & jQuery UI Dialog

In this post I will show you how I implemented a delete confirmation implementation for MVC using the jQuery UI Dialog control. I have done this by adding virtually no customization to the templates generated ASP.Net MVC, and aiming the functionality to be as reusable as possible.

Our Objective

When a user clicks the “Delete” button on a list (or elsewhere), we are going to show a confirmation dialog. If the user confirms, the record will be deleted. If he/she cancels, no action will be taken. In essence, this is what we are trying to do:

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Notes form Visual Studio 2010 At the Movies event (Part 1)….

On April 20, I attended the Microsoft Event “Visual Studio 2010 – At the movies”. One of the best events I’ve attended lately (content-wise), which speaks very well of the organizing partner Object Sharp. I took a few notes and wanted to share them with all of you. Here it goes:

Continue reading “Notes form Visual Studio 2010 At the Movies event (Part 1)….”

.Net (c#) Oodle API wrapper

I recently had the need to interact with Oodle as a way to feed a classified site.

I was suprise to see that while they had php and java libraries/samples already available, but they did not have a .Net one. I searched on their forums and on the web and did not find a library I could use.

Since I had to interact with the api, I decided to make a library, and publish it as an open source component so other developers can use it.

You can find the library at: http://www.codeplex.com/oodlenet; all the references, source code & samples are included in the workspace.

I hope this helps!

C#: Asynchronical Function Calls

As a Web Developer, I’ve frequently have had the need to make asynchronical function calls.

Usually, you need to do async calls when:

Function takes a long time to process
There is no need to present a response to the user

In this example, I will be showing some code I use on my Facebook Application (Network Trotters) to update the users profiles.

As a quick contextual background, user profiles are cached on Facebook’s side, and periodically I need to clear the cache so it is updated. This action can take a bit of time when you have a high number of users, but it doesn’t really require any response to the user.

There are 3 main things you need to do to create an async call:

Create a delegate with the signature you would like
Implement a Function with the same function as the delegate
Call the delegate

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