Syntactic and semantic validation
The preceding recipe is one form of syntactic validation, where we validate the correctness of the field's structure (in this case, the names should only contain alphabetical characters).
Another type of validation is based on semantics, where the validity of the input relies on a specific business context.
Creating a custom validation attribute to implement semantic validation
In semantic validation, a context check is done to ensure that the data conforms to a business rule. Using our Online Banking app as an example, we can define a business rule, stating that a customer must have a reputable email address before a record can be created.
In this recipe, you will learn how to perform semantic validation using custom validation attributes.
Getting ready
Request a free API key at https://emailrep.io/key. EmailRep is a simple public API for checking an email's reputation. Once your request has been approved, you will receive...