Before setting validation rules, which of the following needs to be created?

To set validation rules effectively in Mendix, it's essential to first create entities. Entities are fundamental components of a Mendix application that represent data models. They define the structure of the data within your application, including attributes and their relationships. Validation rules are applied to ensure that the data being entered into these entities conform to specified criteria, maintaining the integrity and consistency of the data.

When validation rules are set, they typically reference the attributes within an entity to enforce constraints such as data types, required fields, or specific formats. Without having defined the entities first, there would be no context or structure in which to apply these validation rules effectively.

While attributes are indeed important and come into play during the validation process, they are part of the entity structure. Microflows and pages, on the other hand, serve different roles within the Mendix environment, focusing on application logic and user interface, respectively, rather than the foundational data structure needed for validation.