Model Validation

This document provides a summary of when, where and how model validation should be applied within the solution.

Overview

Validating input is required across the solution in many places, from a user submitting a simple string to perform an organisational search on an HTML <form> through to complex types with potentially dependent fields in the body of an API POST. This is solved in the solution using a combination of DataAnnotations and FluentValidation.

DataAnnotations

DataAnnotations should be used where simple validation is required, on relatively small models. Built-in attributes should be used in the first instance, or IValidateableObject implemented if this is not sufficient. These validations should be verified via integration tests.

This type of model validation is used far more often in the Web project compared to elsewhere.

FluentValidation

FluentValidation should be used where complex validation is required, on potentially much larger models with dependencies. Inheritance is encouraged where possible, to avoid duplication. AbstractValidator<T> instances should be registered in the service collection and consumed using IValidator<T>. These validations should be verified via unit tests.

This type of model validation is used far more often in the Platform project compared to elsewhere.