Posts

Init-only Properties

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.NET 5 is out! And with it, C# 9, which adds a lot of new features to the language. In this post, I'm going to talk about one of my favorites, init-only properties . Immutability Before C# 9 Before C# 9, we can make a class immutable by using getter-only auto properties together with a constructor whose arguments are used to populate those properties: public class Product { public Product(string name) { Name = name; } public string Name { get; } } This is an effective way for making classes immutable. We cannot change the property's value after the class has been instantiated: var product = new Product("Cool Product"); product.Name = "Cooler product"; // compile error We even can't change it from within the class: public class Product { public Product(string name) { Name = name; } public string Name { get; } public void SomeMethod() { Name = "Cooler product...
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Web API Without Controller

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If the mantra of "thin controllers, fat models" is followed to the extreme, it would result in very short controller methods, sometimes even only a couple of lines long. Today I am experimenting with doing away with controllers entirely, and just mapping routes directly to methods that execute the business logic. The code in this post can be found in: https://github.com/ojraqueno/web-api-without-controller Setting Up the New Project First, I created the web API project template using dotnet new : dotnet new webapi -n ControllerLessWebAPI That will create a new API project for me inside the ControllerLessWebAPI folder. I can run that project by going into the directory and running dotnet run : dotnet run It will start the website, which in my case is located in localhost port 5001. If I go to https://localhost:5001/weatherforecast , I can see some random JSON data being returned. Removing the Controller The starter template contains a WeatherControlle...
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Getting Started with Python

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I usually talk about .NET topics, but today I want to talk about Python. Big shout out to my partner, who is a Python developer, for inspiring me to write about Python. Python Summary For the .NET people out there, here is a quick summary of the Python programming language: Concise and readable syntax, suitable for programmers of all levels Dynamically typed and interpreted, ideal for rapid application development and prototyping Consistenly rated as one of the most popular programming languages in the TIOBE Index and StackOverflow survey Widely used for web and data science applications To install Python, go to https://www.python.org/downloads/ and download the version you want. I would recommend getting the 3+ version. I am using version 3.9.0 for this post. During installation, it might ask you if you want to add Python to the PATH. I would recommend checking this option so that you can run Python from any location in your command prompt or terminal. Pyth...
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ASP.NET MVC vs ASP.NET Core: Practical Differences

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ASP.NET Core has been around for a while, but not everyone is using the new framework yet. If you're someone who's migrating from ASP.NET MVC to ASP.NET Core, you might be wondering what the differences between the two frameworks are. In this post, I will share the main differences between the two, from the point of view of a developer who has worked with both. Here is an overview: Dependency injection is built-in. Controllers are unified. Client-side assets are centralized. And more - read below! Dependency injection is built-in Dependency injection is a popular pattern in object-oriented languages that helps make code maintainable. With ASP.NET MVC, developers had to make use of 3rd-party NuGet packages to enable dependency injection in their projects. In ASP.NET Core, dependency injection is baked into the framework. There is no need to use any NuGet package, although using 3rd party DI packages is still supported. Dependency injection is supported n...
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Solved: Unable to publish to Azure App Service from Visual Studio

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I recently created an Azure App Service and tried to publish a new ASP.NET Core web app using its publish profile downloaded. When i did that, I encountered an error: Web deployment task failed. (Could not connect to the remote computer ("[redacted].scm.azurewebsites.net"). On the remote computer, make sure that Web Deploy is installed and that the required process ("Web Management Service") is started. Lear more at: http://go.microsoft.com/fwlink/?LinkId=221672#ERROR_DESTINATION_NOT_REACHABLE.) The requested resource does not exist, or the request URL is incorrect. Error details: Could not connect to the remote computer ("[redacted].scm.azurewebsites.net"). On the remote computer, make sure that Web Deploy is installed and that the required process ("Web Management Service") is started. Lear more at: http://go.microsoft.com/fwlink/?LinkId=221672#ERROR_DESTINATION_NOT_REACHABLE. The remote server returned an error: (404) Not Found. Here...
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Immutability

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Last time, we looked at pure vs impure functions and we said that functional programming favors pure over impure functions. Using pure functions leads to another concept: immutability . Immutability means that a variable can only have its value set once. After that, the value never changes. So much so that in functional programming, the phrase "assigning to a variable" is often replaced by "binding to a symbol", since the word "variable" is not applicable anymore. Let's consider a non-immutable example: // Declare a class named Car public class Car { public string Color { get; set; } public bool IsStarted { get; set; } } // Instantiate a new instance var myCar = new Car { Color = "Red", IsStarted = true }; // After that, change the values of the car's properties myCar.Color = "Blue"; myCar.IsStarted = false; The properties inside of the Car class are not immutable since they can be changed after...
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Pure vs Impure Functions

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My partner, who is also a developer, once asked me what the difference between functional and object-oriented programming is. There are many differences, and this post explores one of them: the usage of pure and impure functions. What are pure and impure functions? A pure function does not have side effects. A side effect is a change in state that happens outside of a function that gets persisted even after the function goes out of scope. Impure functions are everything else. Here are some examples to clarify. First, a pure function: // Pure int GetSum(int a, int b) { return a + b; } That is a pure function, because it does not affect any state that is outside the scope of the function. Consider this impure equivalent: // Impure int sum = 0; void ComputeSum(int a, int b) { sum = a + b; } That is an impure function, because it modifies the sum variable, and the modification persists even after the method has gone out of scope. When using an object-or...
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