Search code examples
mvp

In MVP where to write validations

In Model-View-Presenter pattern where should we write validations of user input.

Solution

  • Domain specific rules/validations should be in the Model. You can have a model.validate() to let you know if the rules are not violated. Look at Rails model (ActiveRecord) classes for a good implementation of this concept.

    The View should make it difficult for the user to key in invalid input. So 'entering a string for a numeric value' class of input errors should be nipped before reaching the presenter. There may be some duplication of validations between model and view. E.g. AttributeX must range between 1-100. This must be validated in the model.. at the same time you may want to slot in a spinner in the UI with the minValue and maxValue range set to 1-100.