CODEWITHSUNDEEP
ruby-on-railspostgresqlrails-activerecord
Nathan Long
Nathan Long

Reputation: 125902

Can I use PostgreSQL's "Special Date/Time Inputs" with ActiveRecord?

PostgreSQL supports several "Special Date/Time Inputs", strings that it interprets upon execution. Eg, 'now' means "current transaction's start time", and 'infinity' means "later than all other timestamps".

ActiveRecord does not seem to understand these - eg, SomeRecord.update!(updated_at: DateTime.current) works, but SomeRecord.update!(updated_at: 'now') tries to execute the UPDATE query with a NULL.

These special strings do work in Rails fixtures, because they go straight to the database. But is there a way to use them with an instantiated model?

Upvotes: 1

Views: 190

Answers (2)

Nathan Long
Nathan Long

Reputation: 125902

Use .update_column

Eg, some_record.update_column(:updated_at, 'now').

Warning - this bypasses validations, callbacks, and normal setting of timestamps; it just issues an immediate UPDATE query.

Despite that, ActiveRecord contributor Sean Griffin said "update_column is probably the best 'hacky' answer" and that special string values like this aren't really well-supported and maybe shouldn't be. (I think I agree - it would make validation really awkward, both for ActiveRecord and in your own models.)

A compromise to get validations, etc

Given that this is a "direct to database" method, one possible compromise to avoid skipping validations and callbacks would be:

ActiveRecord::Base.transaction do
  record.updated_at = Time.current         # temporary value
  record.save!                             # with validations, etc
  record.update_column(:updated_at, 'now') # final value
end

Caveats for the console

A couple of other caveats I noticed for doing this in the console:

  • Inspecting the record afterwards, I saw 'now' as the value for created_at. Only after doing some_record.reload did I see the timestamp.
  • Doing this repeatedly didn't seem to give a new timestamp. I think that's because 'now' is "current transaction's start time", and maybe each rails console session uses one transaction. If I started a new console, I got a new value for 'now'

Upvotes: 0

Thomas Walpole
Thomas Walpole

Reputation: 49870

You can set the value with raw_write_attribute(:updated_at, 'now')

Upvotes: 1

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