Reading Attribute Data
Explore how to define and apply custom attributes in C#, then use reflection to read and validate these attributes at runtime. Understand how attributes add metadata to class members, enabling flexible validation logic that can be reused across properties without repetitive code changes.
We'll cover the following...
Attributes are special constructs that let us inject additional metadata into an assembly. Attributes can be applied both to the entire type and to individual parts of the type, such as properties, methods, and fields. Attributes have many applications, but we most often use them to validate that a member or type meets certain conditions.
Suppose we have a minimum length requirement for a password in our system. We have a class called UserProfile with the following definition:
public class UserProfile{public string Username { get; set; }public string Password { get; set; }}
We could achieve this by creating a method to validate that the Password property meets the minimum length requirement. However, if we later want to enforce the minimum length rule on the Username property, we must modify that method to include a corresponding check for every new property.
Rather than implementing repetitive validation logic, we can decorate properties with attributes and use ...