CODEWITHSUNDEEP
ruby-on-railsactiverecord
user1225335
user1225335

Reputation: 23

Updating current value in ActiveRecord (Rails)

in my application lots of objects are already preloaded by Rails.

Now I like to update some of these object attributes. Unfortunately some of these objects are related to the same object in my database. When I add a value to myObject.balance (myObject.balance += value), the attribute balance in differentButSameObject has still the same value.

One solution could be reloading the object. I would prefer to update the value like this: UPDATE myTable SET balance = balance + 10 WHERE id = 1.

Is this possible?

Upvotes: 2

Views: 1754

Answers (2)

Roman
Roman

Reputation: 13058

You can add the following code to your model. It uses the update_counters which performs a proper query (that does COALESCE, for instance):


def inc(counter, by = 1)
  raise "Cannot update column of a non-persisted model" unless persisted?
  self.class.update_counters(id, counter => by)
  increment(counter, by)
end

Upvotes: 0

Novae
Novae

Reputation: 1171

You could use ActiveRecords update_all statement:

Object.where(:id => 1).update_all("balance = balance + 1")

Upvotes: 6

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