Rails ActiveRecord: Updating attributes (object fields)

2017-03-07 ·

Ruby provides write accessors to change attributes (another name for fields) of an object. Those accessors may be redefined.

user.name = "Zaiste"

name will be marked as dirty and the change will not be persisted in the database. You can undo the change using reload! or persist the change in the database by calling user.save.

user.write_attribute(:name, "Zaiste")

write_attribute is called by the attribute accessor i.e. name= from previous example. The change will not be persisted the database. This method can be to bypass this accessor when you need a special behaviour at the time of setting given attribute.

def name=(new_name)
  write_attribute(:name, new_name.downcase)
end

You can change few attributes at once using attributes accessor or assign_attributes method.

user.attributes = { name: "Zaiste", age: 21 }
user.assign_attributes { name: "Zaiste", age: 21 }

This won't persist changes in the database. Unspecified attributes won’t be changed.

Use update_attribute to change an attribute and persist it without running validations.

user.update_attribute(:name, "Zaiste")

Use update to change an attribute, check the validations and persist the change if validations pass.

user.update(name: "Zaiste")

You can find an object and update it with a one command using update as class method.

User.update(111, name: "Zaiste")

The validations will be checked.

You can find and update several objects at once using update class method.

User.update(
  [123,234,345],
  [
    { name: "Zaiste" },
    { name: "Józio", age: 7 },
    { name: "Francois", age: 18, city: "Paris"},
  ]
)

You can also update all objects at once using update_all class method.

User.update_all(name: "Zaiste")

This method won’t check the validations.

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