A set of Math questions that my kiddo enjoys during the Summer Break. — Numbers and Counting A bunch of apples are arranged in a line, but a peach is mixed in the line. If we count from the beginning, the peach is the fifth in line. If we count from the end, then the peach is the seventh in line. How many apples are there in…

A Fist Look at Minimal APIs in .NET 6 — As announced in the .NET 6 Preview 4 blog, .NET 6 will release an improvement to ASP.NET Core: minimal APIs for hosting and routing in web applications. With these streamlined APIs, we can build microservices and small HTTP APIs with much less ceremony. This is exciting and let’s take a…

How to configure Serilog and split logs into different files — In this post, I will first show you some basics of configuring Serilog for logging in .NET/ASP.NET applications. Then moving on to the topic of how to split or suppress logs. The source code can be found in my GitHub repository. Serilog Configuration Basics Serilog is a famous logging tool for .NET and…

How to Render String Templates in C# — C# has a feature, String Interpolation, to format strings in a flexible and readable way. The following example demonstrates the way how we usually output a string when we have data beforehand then pass data to the template string. On the other hand, the String Interpolation doesn’t work…

How to unit test action methods with HttpContext, Request, ModelState — We do different levels of tests against controllers. When unit testing controller logic, the test only executes the action method itself without going through the framework’s request/response pipeline. In other words, the filter attributes (e.g., the Authorize attribute ), model binding, and middlewares do not affect unit tests for controllers…

How to Design and Implement Robust Background Jobs in Our Applications — Most background jobs are running behind the scene and are transparent to end-users, and admins usually don’t need to worry about the nitty-gritty of how the system automates tasks or when the system executes them. In some cases, product owners may know that there are background jobs supporting the application…

How to implement and test IP restrictions in an ASP.NET Core Web API project — We sometimes want to limit our application to only certain IP addresses or IP network ranges. For example, during beta testing, we prefer to only allow admins and preselected testers to access the new website. …

How to return a file from an API endpoint in ASP.NET Core and create an HTML download link. — In this article, I will use a demo Web API application in ASP.NET Core to show you how to transmit files through an API endpoint. In the final HTML page, end users can left-click a hyperlink to download the file or right-click the link to choose “Save Link As” in…

Surprise! The arrays are not replaced as a whole. — ASP.NET Core uses configuration providers to read configuration key-value pairs from a variety of sources. You can read more about configuration in ASP.NET Core in its official documentation, which has covered tons of use cases in detail. Recently, when I set a JSON array in the appsettings.json files in an…