Why You Can’t Access Struct Fields Through Interfaces in Go (and How to Fix It)

In Go, interfaces define method contracts, not field access, leading to compile-time errors when trying to directly access struct fields through an interface. When a struct is assigned to an interface, the struct's value is hidden, requiring specific methods to access it. Common scenarios, like API payload handling, illustrate this limitation, as interfaces don't inherently know about struct fields like "Name". Type assertion provides a solution by confirming the underlying type, allowing access to its specific fields, often used with `if` statements or type switches. Alternatively, reflection can dynamically access fields, but it should be used cautiously due to its complexity and potential for errors. Go's strict typing aims to prevent bugs by clearly separating interface contracts from struct implementations. Understanding that interfaces don't carry struct fields clarifies why direct field access fails. Type assertion and reflection are tools to overcome this limitation when necessary. Choose the method that best suits your need and the level of dynamism needed by your code. The full discussion includes code samples and reflection examples.