API Design Patterns

27 Request validation

This chapter covers

• Why some API methods should support pre-request validation
• How to manage interactions with external dependencies for validation requests
• Addressing special side effects for methods in validation requests

APIs can be confusing. Sometimes they can be confusing to the point where it’s unclear what a result will be for a given API call. For safe methods, we have a simple solution to figure out the result: just give it a try. For unsafe methods, though, that solution will obviously not work. In this pattern, we’ll explore a special validateOnly field we can add to request interfaces, which will act as a mechanism by which we can see what would have happened if the request was executed, without actually ...