Executing custom validation before record created?

Question

I want to execute a custom validation before the record is created?

It looks as if this is the right method: before_validation_on_create. For example:

before_validation_on_create :custom_validation

But am not sure. Any help would be appreciated.

I see there is: validate_on_create.

keruilin
– keruilin

2010-06-19 23:28:52 +00:00
Commented Jun 19, 2010 at 23:28 — keruilin
– keruilin, Commented Jun 19, 2010 at 23:28

smek · Accepted Answer · 2012-06-28 10:25:33Z

34

In rails 3

before_validation_on_create :do_something

has been replaced with:

before_validation :do_something, :on => :create

answered Jun 28, 2012 at 10:25

smek

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1 Comment

mwfearnley Over a year ago

I don't think this addresses the question of running custom validations before creation, but it answers the question I came here with.

John Bachir · Accepted Answer · 2015-03-17 14:20:02Z

20

before_validation_on_create hooks happen before validation on create… but they aren't validations themselves.

What you probably want to do is use validate and a private method which adds to the error array. like this:

class IceCreamCone

  validate :ensure_ice_cream_is_not_melted, :before => :create

  private
    def ensure_ice_cream_is_not_melted
      if ice_cream.melted?
        errors.add(:ice_cream, 'is melted.')
      end
    end
  end

edited Mar 17, 2015 at 14:20

answered Jun 20, 2010 at 0:21

John Bachir

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2 Comments

Kazim Zaidi Over a year ago

I like your example in particular.

bpromas Over a year ago

This example has me giggling like a little girl at the office

amliving · Accepted Answer · 2017-02-23 23:35:29Z

13

The following worked for me in Rails 5:

validate :custom_validation_method, :on => :create

Running

validate :custom_validation_method, :before => :create

gave me following error:

Unknown key: :before. Valid keys are: :on, :if, :unless, :prepend.

answered Feb 23, 2017 at 23:35

amliving

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Comments

Jamie Wong · Accepted Answer · 2010-06-19 23:24:01Z

2

There's a great resource here for information on callbacks and the order they happen in:

http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html

answered Jun 19, 2010 at 23:24

Jamie Wong

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2 Comments

Terra Kestrel Over a year ago

Why was this downvoted? It points to very clear documentation describing the solution to the OP's problem, and better understanding of validations in general.

henrebotha Over a year ago

It got downvoted because it's not an answer, it's just a link to an external reference.

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