instance method `exists?`

Ruby on Rails 3.2.22.5

Since v3.0.20

Available in: v3.0.20 v3.1.12 v3.2.22.5 v4.0.13 v4.1.16 v4.2.9 v5.2.8.1 v6.0.6 v6.1.7.10 v7.0.10 v7.1.6 v7.2.3 v8.0.4 v8.1.2

Compare with:

exists?(id = false)

Returns true if a record exists in the table that matches the id or conditions given, or false otherwise. The argument can take five forms:

Integer - Finds the record with this primary key.
String - Finds the record with a primary key corresponding to this string (such as '5').
Array - Finds the record that matches these find-style conditions (such as ['color = ?', 'red']).
Hash - Finds the record that matches these find-style conditions (such as {:color => 'red'}).
No args - Returns false if the table is empty, true otherwise.

For more information about specifying conditions as a Hash or Array, see the Conditions section in the introduction to ActiveRecord::Base.

Note: You can’t pass in a condition as a string (like name = 'Jamie'), since it would be sanitized and then queried against the primary key column, like id = 'name = \'Jamie\''.

Examples

Person.exists?(5)
Person.exists?('5')
Person.exists?(:name => "David")
Person.exists?(['name LIKE ?', "%#{query}%"])
Person.exists?

Parameters

id opt = false

Source

# File activerecord/lib/active_record/relation/finder_methods.rb, line 187
    def exists?(id = false)
      id = id.id if ActiveRecord::Base === id
      return false if id.nil?

      join_dependency = construct_join_dependency_for_association_find
      relation = construct_relation_for_association_find(join_dependency)
      relation = relation.except(:select, :order).select("1 AS one").limit(1)

      case id
      when Array, Hash
        relation = relation.where(id)
      else
        relation = relation.where(table[primary_key].eq(id)) if id
      end

      connection.select_value(relation, "#{name} Exists") ? true : false
    rescue ThrowResult
      false
    end

Defined in activerecord/lib/active_record/relation/finder_methods.rb line 187 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveRecord::FinderMethods

Signature

Examples

Parameters