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Whenever you’re dealing with code that can run into transient errors, it’s a good idea to implement retries. Transient errors, by definition, are temporary and subsequent attempts should succeed. When you retry with a delay, it means you think the the transient error will go away by itself after a short period of time. When … Read more
EF Core has built-in retry functionality. To use it, you can call options.EnableRetryOnFailure(), like this: The retry logic is contained in execution strategy classes. The above code is using the default execution strategy class (SqlServerRetryingExecutionStrategy). When you execute a query, it goes through the execution strategy class. It executes the query and checks for transient … Read more
There’s two ways to unit test code that writes to the console (Console.WriteLine() / Console.Write()): In this article, I’ll show how to do both options. Option 1 – Capture the output with Console.SetOut() Let’s say you want to unit test the following code that outputs to the console with Console.WriteLine(): You can unit test this … Read more
You can get all types from an assembly by doing a reflection-only load. This allows you to read type info from metadata without running the typical errors associated with fully loading an assembly. The way to do a reflection-only load is different in .NET Framework and .NET Core. I’ll show examples of how to do … Read more
In this article, I’ll show how to use the Select-String PowerShell command to search files in a directory with a regex pattern. I’ll first explain the basic syntax, and then I’ll show a few common search scenarios. Pattern, path, and alias Select-String has two main parameters: Note: The command name is not case-sensitive. You can … Read more
You can use the is operator to check if an object is a certain type. Here’s an example: You can also use the is operator to declare a variable of the target type, like this: Note: The employee object is only available in the if block, but IntelliSense shows it out of its scope. If … Read more
Padding a 2D array on all sides means adding new rows on the top and bottom, new columns on the left and right, and then copying the original elements to the center of the padded array. It looks like this: There are two approaches for copying the elements. You can either copy individual items in … Read more
Table-valued parameters (TVP) allow you to send multiple rows of data as a parameter into SQL queries. This is useful for SELECTs and INSERTs. In this article, I’ll show how to create a TVP in SQL Server and then use it in queries with Dapper. 1 – Create the TVP in SQL Server To be … Read more
I was reading about logging in ASP.NET when I came across this statement about logging to the database: When logging to SQL Server, don’t do so directly. Instead, add log messages to an in-memory queue and have a background worker dequeue and insert data to SQL Server. Paraphrased from Microsoft – No asynchronous logger methods … Read more
Problem You’ve configured user secrets properly, but the framework will not swap in the secret value at runtime. It appears to not be loading secrets.json at all. Check if you’re using GenerateAssemblyInfo=false in your .csproj file. When you add a user secrets file, it generates a user secrets guid and puts it in your .csproj … Read more
When a background service throws an unhandled exception in ExecuteAsync(), you have two options: You can change the behavior if the default isn’t what you want (notice the default behavior changed in .NET 6). In .NET 6+, you can configure the behavior in the initialization code. Here’s an example of making it ignore crashed background … Read more
The options pattern is an indirect way to dependency inject settings into a registered service. If you’re using code that implements the options pattern, then you’re required to supply an IOptions<T> object. For example, let’s say you’re using the MovieService class and it has the following constructor: This requires you to supply the IOptions<MovieSettings> parameter. … Read more
When you try to call BuildServiceProvider(), you get the following warning: Warning ASP0000 Calling ‘BuildServiceProvider’ from application code results in an additional copy of singleton services being created. Consider alternatives such as dependency injecting services as parameters to ‘Configure’. There are two scenarios where you may be calling BuildServiceProvider() because you want to resolve services … Read more
Let’s say you have a hosted BackgroundService called DatabaseLoggerService. It runs in the background and logs messages to the database. It has the following definition: You want your controllers to use this for logging. In other words, you want them to depend on ILoggerService, not the concrete DatabaseLoggerService class. First, constructor inject ILoggerService into your … Read more
In a consumer/producer scenario, there are many reasons why you might want the consumer to read a batch of items. Maybe you’re bulk inserting into the database, or sending a payload with HttpClient. Sending lots of individual items over the network can be costly, and waiting for a full batch of items before sending is … Read more
If you try to set a list control’s DataSource to a type it can’t handle, then you’ll get the following exception: System.ArgumentException: Complex DataBinding accepts as a data source either an IList or an IListSource. (Parameter ‘value’)at System.Windows.Forms.ListControl.set_DataSource(Object value) Note: This applies to all controls that subclass ListControl, such as ComboBox and ListBox. This is … Read more
When you want to use NLog in ASP.NET, the first step is to install and configure NLog. Then you can either use it directly or fully integrate it and ASP.NET. Use NLog directly if you prefer to have static ILogger properties, instead of using dependency injection. The downside of this approach is that you’ll have … Read more
There are three requirements for unit testing a middleware class: Here’s an example: This is a simple test that only checks the response status code. By passing in DefaultHttpContext, you have control over the request and response objects. You can set the request to whatever you need, and then verify the response. I’ll show examples … Read more
The ASP.NET Core request pipeline has middleware components (classes or lambdas) for processing requests. There are many built-in middleware components, such as AuthorizationMiddleware and HttpsRedirectionMiddleware. You can create custom middleware. I’ll show how below. 1 – Create middleware class In this example, I’ll show how to create a middleware class which is based on the … Read more
When you’re using the same HttpClient instance to send multiple requests, and you want to change the timeout per request, you can pass in a CancellationToken, like this: You can’t change HttpClient.Timeout after the instance has been used. You have to pass in a CancellationToken instead. There are other key points to know when trying … Read more
ASP.NET Core uses System.Text.Json as the default JSON serializer. To configure the JSON serializer options, call AddJsonOptions() in the initialization code: Calling AddJsonOptions() gives you access to the global JsonSerializerOptions object. This is used for all requests / responses. You can configure the options and add converters (including your own custom JSON converters). ASP.NET Core’s … Read more
By default, ASP.NET Core uses System.Text.Json for JSON serialization. If you want to use Newtonsoft instead: Note: Before .NET 6, do this in Startup.ConfigureServices(). Install the right package Microsoft packaged up Microsoft.AspNetCore.Mvc.NewtonsoftJson based on the framework version, so you can’t just install the latest package. You have to find the latest one for the framework … Read more
System.Net.Http.Json provides extension methods that simplify getting and sending JSON with HttpClient. Internally, it uses System.Text.Json for serialization. What if you want to use Newtonsoft instead of System.Text.Json? You can use the following extension methods for that: These are modeled off of the extension methods in System.Net.Http.Json. HttpClient is used to fetch the JSON content … Read more
The simplest way to get and send JSON with HttpClient is to use the GetFromJsonAsync() and PostAsJsonAsync() extension methods (in System.Net.Http.Json), like this: Note: You have to install the System.Net.Http.Json package if you’re using a framework version before .NET 5. These extension methods use System.Text.Json for serialization. They simplify things by abstracting away the common … Read more
When the built-in dependency injection functionality is trying to create a type, it tries to resolve all of the constructor parameters. If it can’t resolve one of the parameters, it’ll throw a variation of one of these exceptions: The error you get will depend on how you’re doing registration. First, I’ll show the solution. Then … Read more