docs/documentation/advanced-features/validation-of-variables/index.markdown
---
layout: default
title: Validation of variables
---
To validate a variable, each time before it is set, define a validation:
```ruby
validate :some_key do |key, value|
if value.length < 5
raise Capistrano::ValidationError, "Length of #{key} is too short!"
end
end
```
Multiple validations can be assigned to a single key. Validations will be executed in the order of registration.