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C# – Get temp folder path and create a temp file

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You can use Path.GetTempPath() to get the user’s temp folder path. Here’s an example: I’m running this in Windows, so it outputs my temp folder path: Path.GetTempPath() gets the temp folder path by checking environment variables (TMP, TEMP, USERPROFILE). It falls back to returning the system temp folder. Create a temp file Once you have … Read more

C# – How to create a file and write to it

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There are a few ways to create a file and write to it using the .NET File API (in System.IO). The simplest way is to use high-level methods like File.WriteAllText() and File.WriteAllLines(), specifying the file path and string(s) to write to the file. Here’s an example of using these (and their async equivalents): These high-level … Read more

C# – ConfigurationSection.Get() returns null

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When you use ConfigurationSection.Get() to load an object from appsettings.json, it returns null if the section doesn’t exist. Since you’re probably not expecting this to be null, this can lead to problems surfacing in unexpected places, such as getting a NullReferenceException: Note: If you’re using ASP.NET Core, you’ll be referring to the config via builder.Configuration … Read more

ASP.NET Core – How to receive a file in a web API request

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When the client posts a file in a multipart/form-data request, it’s loaded into an IFormFile object. This contains file information (such as the file name) and exposes the file content as a stream. This allows you to save the file content or process it however you want to. You can access the IFormFile object through … Read more

C# – How to update appsettings.json programmatically

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You have to overwrite the appsettings.json file to be able to update values programmatically. You have to deal with the whole file, not individual parts of it. The process can be summarized in the following steps: There are two options for deserialization. You can either 1) Deserialize appsettings.json into a dynamic object or 2) Load … Read more

How to use relative paths in a Windows Service

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Relative paths are resolved relative to the current working directory. When you’re running a Windows Service, the default working directory is C:\Windows\system32 or C:\Windows\SysWOW64. Therefore relative paths are resolved from these system folders, which can lead to problems when read/writing files. Here are the most common problems you’ll run into: System.IO.DirectoryNotFoundException: Could not find a … Read more