Automatically parsing date/time parameters in rails

Question

Is there a way to automatically parse string parameters representing dates in Rails? Or, some convention or clever way?

Doing the parsing manually by just doing DateTime.parse(..) in controllers, even if it's in a callback doesn't look very elegant.

There's also another case I'm unsure how to handle: If a date field in a model is nullable, I would like to return an error if the string I receive is not correct (say: the user submits 201/801/01). This also has to be done in the controller and I don't find a clever way to verify that on the model as a validation.

Check if helps: https://stackoverflow.com/questions/1370926/rails-built-in-datetime-validation -- https://stackoverflow.com/questions/597328/how-do-i-validate-a-date-in-rails — iGian, Aug 24 '18 at 17:12

Billy Kimble · Answer 1 · 2018-08-24T14:34:16.003

1

If you're using ActiveRecord to back your model, your dates and time fields are automatically parsed before being inserted.

# migration
class CreateMydates < ActiveRecord::Migration[5.2]
  def change
    create_table :mydates do |t|
      t.date :birthday
      t.timestamps
    end
  end
end

# irb
irb(main):003:0> m = Mydate.new(birthday: '2018-01-09')
=> #<Mydate id: nil, birthday: "2018-01-09", created_at: nil, updated_at: nil>
irb(main):004:0> m.save
=> true
irb(main):005:0> m.reload
irb(main):006:0> m.birthday
=> Tue, 09 Jan 2018

So it comes down to validating the date format, which you can do manually with a regex, or you can call Date.parse and check for an exception:

class Mydate < ApplicationRecord
  validate :check_date_format

  def check_date_format
    begin
      Date.parse(birthday)
    rescue => e
      errors.add(:birthday, "Bad Date Format")
    end
  end
end

edited Aug 24 '18 at 14:34

answered Aug 24 '18 at 14:08

Billy Kimble

798
3
9

That's what I meant by "parsing manually". I don't want to do that for each date field I have :) – dgmora Aug 24 '18 at 14:12
ah I see you edited your question to include that. I'll add another answer – Billy Kimble Aug 24 '18 at 14:21
Yeah I didn't see automatically parsing was happening. Issue is that if the string is bad it will just return nil – dgmora Aug 24 '18 at 15:29
You could add _before_type_cast to the variable name to get the invalid date and parse it manually. E.g. birthday_before_type_cast – Mark Robinson Jun 07 '23 at 11:09

Automatically parsing date/time parameters in rails

1 Answers1