Home/ Questions/Q 962439
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-16T01:30:23+00:00

So I have been using data annotations for my validation in an MVC project

  • 0

So I have been using data annotations for my validation in an MVC project and they seem to work in most scenarios.

Here are two examples in my current project where they don’t seem to fit and I am unsure of the best place to put the validation.

1) I have a Join League page that contains a form where the logged in user enters their team name and clicks to join the league. When they submit the form i need to make sure that the current user doesn’t already have a team in the league. So it basically needs to query the db for that user id and league id to make sure no team exists for the user. My ViewModel does not contain user id, since it is not relevant to the view.

2) On this same page, I also need to make sure the team name is unique. This is easy if you are just looking to see if it exists in a table. You create a custom validation attribute that query’s a table for the value of the field. However i need to see if it exists in a table for a certain league id. (the league they are joining.)

It doesn’t seem like Data Annotations are an ideal solution for anything other then trivial validation. My current solution is to query the db at beginning of post action method, and add the error to the ModelState manually. (yes, terrible)

Any ideas?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    I think it may help to put some thought into the difference between Input Validation and Business Logic. Ayende has some thoughts on this here

    Rules like ‘When they submit the form I need to make sure that the current user doesn’t already have a team in the league’ sounds like Business Logic, not Input Validation, and you may want to handle it in a different way. This logic could, for instance, go into a ‘CanSave’ method on a ‘User’ class or something similar – the key thing is to separate this from Input Validation if you can.

    • 0