Enhance String Semantics with the StringSyntax Attribute

The StringSyntax attribute was added in .NET 7, so let's just say it's a relatively new feature (at the time of writing). This new attribute allows you to specify the intended syntax or format of a string.

Having a feature like this can make our code more readable and safer. In this short .NET tip, I will show you how it works and why it is useful.

What Is StringSyntax? 🤔

The StringSyntax attribute can only be applied to string parameters, properties, or fields in .NET. We do this to indicate to other developers (and ourselves 😅) the specific format or syntax that we expect the string to be within.

Ever heard of code analyzers? Well... by adding the StringSyntax attribute we can give them a hint about the semantic meaning of a string we are expecting. This can help with easier validation and give developers a better experience due to improved IDE support. I am talking about syntax highlighting here.

Why Use StringSyntax? 💭

You probably already have a good idea of why this is a good thing to make use of 😄 but here are my top three reasons why I think you should start using it.

1. Better readability - By indicating that a string follows a specific syntax (e.g., Json, Regex, or Uri), you can make the intended purpose of the string clearer to anyone reading, refactoring, or consuming the code. ✅
2. IDE support - Visual Studio and other IDEs like Rider can use the attribute to give the developer a syntax highlighting, autocompletion, and even validation on the string. What's not to like here!? 👌
3. Minimize the risk of errors - By indicating a specific syntax for your string, you can avoid misinterpretation errors. Example - Imagine a method might expect a JSON-formatted string rather than plain text, and the attribute can help ensure the correct format.

How to Use StringSyntax 🧑‍💻

No .NET tip without a demonstration 🧑‍💻 Here is a quick example of how you can use StringSyntax in your code or get an idea of how it's implemented. It's luckily pretty straightforward.

using System.Diagnostics.CodeAnalysis;

public class ExampleClass
{
    public void ConfigureRegexPattern([StringSyntax(StringSyntaxAttribute.Regex)] string regexPattern)
    {
        // Code that uses regexPattern with the assumption it's a valid regular expression
    }

    public void SetJsonString([StringSyntax(StringSyntaxAttribute.Json)] string jsonString)
    {
        // Code that processes jsonString as JSON
    }
}

Available Syntax Options ✅

The StringSyntax attribute class provides several common syntax types, you can read more about those in the link below in my resources for this .NET tip.

• Regex - Marks the string as a regular expression pattern.
• Json - Indicates the string should follow JSON formatting.
• DateTimeFormat - Indicates the string should follow DateTime formatting.
• Uri - Indicates a URI format is expected.
• Xml - Indicates XML format.

Use Cases ⚡️

I have tried to think about some use cases for this attribute, and here are my thoughts so far for when I would use it myself.

Resources 📚

StringSyntaxAttribute Class (System.Diagnostics.CodeAnalysis)

Specifies the syntax used in a string.

Microsoft Learndotnet-bot