update(id = :all, attributes) public

Updates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.


  • id - This should be the id or an array of ids to be updated.

  • attributes - This should be a hash of attributes or an array of hashes.


# Updates one record
Person.update(15, user_name: 'Samuel', group: 'expert')

# Updates multiple records
people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } }
Person.update(people.keys, people.values)

# Updates multiple records from the result of a relation
people = Person.where(group: 'expert')
people.update(group: 'masters')

Note: Updating a large number of records will run an UPDATE query for each record, which may cause a performance issue. So if it is not needed to run callbacks for each update, it is preferred to use #update_all for updating all records using a single query.

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July 27, 2011 - (>= v3.0.0)
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Multiple update, on query ?

Person.update(people.keys, people.values)

Will this request issue one or multiple queries to update the table data (as in http://stackoverflow.com/questions/3432/multiple-updates-in-mysql#3466 )

The answer is: it will do TWO queries per updated row. One select and one update.

November 30, 2012
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Beware: virtual attributes are ignored

Even though validations are called, virtual attributes are ignored.