This content originally appeared on DEV Community and was authored by Moses Gathuku
In rails, it is possible to specify when the validation should happen. sometimes you may want to introduce new validation or skip some. Rails on option helps us achieve this.
class Post < ApplicationRecord
validates :body, presence: true
validates :title, uniqueness: true, on: :create
validates :published, exclusion: [nil], on: :update
end
From the above validations:
- it's not possible to create or update a post without a body
- it will be possible to update a post with a duplicate title
- it will be possible to create a record with published nil
Apart from the commonly used on: :create and on: :update rails allow us to provide custom contexts.
class Post < ApplicationRecord
validates :title, presence: true
validates :published_at, presence: true, on: :publish
end
From the above example, we are validating published_at presence on: :publish. Custom contexts are triggered explicitly by passing the name of the context to valid? invalid? or save
post = Post.new(title: "Rails validations")
post.valid? # true
post.valid?(context: :publish) # false
post.save(context: :publish) # false
This content originally appeared on DEV Community and was authored by Moses Gathuku
Moses Gathuku | Sciencx (2022-04-24T19:53:30+00:00) Rails custom validation contexts. Retrieved from https://www.scien.cx/2022/04/24/rails-custom-validation-contexts/
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