Reorder Columns in Spark DataFrame with Select() and Scala

Sometimes, when dealing with a Spark data frame it may be necessary to reorder columns in a certain order. For example, to keep data consistent when trying to union two or more data frames with the same schema but different order of columns. Let's explore how that can be done relatively easy using a select() Spark SQL function.

Incorrect ReSharper Behavior for CS1591 Warning

After upgrading from Visual Studio 16.8.x to 16.9.x the JetBrains ReSharper suddenly started marking a lot of public identifiers in the code as compiler errors with a message: "Missing XML comment for publicly visible type or member...". You can imagine how that can be very annoying.

.NET Web API: Confusing 404 Response to OPTIONS Request for CORS pre-flight

Problem: when a Angular applications sends an OPTIONS request to its own backend to satisfy CORS preflight policy it unexpectedly receives a 404 response from a .NET Core Web API application that effectively blocks an actual data data request from executing correctly. If you have ever experienced this problem, continue reading to understand what the problem is and how to fix it. 

C#/.NET: Validate Anonymous Objects During Unit Testing

Say, we have developed a REST API based on .NET Web API framework and need to write a unit test for an end point that returns a collection of objects. This sounds like a usual trivial task that many developers do all the time. Unless, the API method that we need to test, returns a collection of anonymous objects, that is the API method is written using a C# anonymous or dynamic type to construct objects that are included in the list.

It's totally fine when the endpoint is consumed over HTTP as the result is first serialized into JSON for transfer and then de-serialized back into a JavaScript object on a consumer side. If, however, the endpoint is called directly in C# without JSON conversion, like in a unit test, it's an entirely different story. Let's discuss how we can overcome this issue.

Angular: Mock NgRedux for Unit Testing

If you use Redux in your Angular web application (likely it is an NgRedux from Angular Redux) and develop unit tests for components that depend on the Redux store sometimes it's easier to mock the Redux store rather than deal with incorrect values that it may supply in a test scenario. If this sounds like your situation, read on.

.NET Core OData: How to Construct a DateTime Filter

Say, we need to construct a query to an OData endpoint that filters records by DateTime values. Over the years as OData standard had been evolving there have been various different ways to work with DateTime columns depending on OData version and an implementation of an actual OData service that could have been based on various different frameworks. This being said, it's likely, that a single universal way of constructing a DateTime based filter clause for OData services might not exist. Take this under consideration, and note that the solution presented below had only been tested with OData services that are built with .NET Web API Odata v4.

Reuse a MemoryStream without Writing to a FileStream

MemoryStream is a very useful class as it allows working with a Stream-like data in memory without having dependencies on any external resources like files, etc. Even though the MemoryStream implements an IDisposable interface it does not actually have any critical resources to dispose of, so, explicitly disposing of a MemoryStream object is not strictly necessary as the .NET memory management will take care of it. This specifics presents an opportunity of reusing the MemoryStream object if needed across multiple code scopes.

Best Practices of Working with Date in JavaScript/TypeScript

Date is a built-in type in JavaScript/TypeScript (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) and provides most of the basic needs for manipulating with Date and Time values in the code. Being one of the most well-defined and often used basic types of the language it still generates a lot of confusion, questions and erroneously working code among a wide developers' community. Let's try and figure out some of the best practices that should be applied to the JavaScript/TypeScript code when dealing with the Date type.

A Color Picker in Chrome DevTools

When you are working with CSS and specifically dealing with colors in HEX format it's very handy to be able to quickly find (or pick) a color value anywhere on your screen. There are tools for that, of course, namely, color picker browser extensions, that I used to have. Not anymore. Because, Chrome, that is my main browser, have a Color Picker built into the DevTools. How nice, eh?

Open the DevTools by clicking F12 (or use a menu) and in the Styles panel you can simply click on any color square and the Color Picker will open.

You can use a pipette tool on the left and while it's in the "ON" state and colored blue move it around the screen and click on any color and it will appear in the Color Picker with a HEX value.