Module: ActiveRecord::FinderMethods

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In: `AssociationRelation`, `Associations::CollectionProxy`, `DisableJoinsAssociationRelation`, `Relation`
Defined in:	activerecord/lib/active_record/relation/finder_methods.rb

Constant Summary

ONE_AS_ONE =
# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 7
```
"1 AS one"
```

Instance Method Summary

#exists?(conditions = :none) ⇒ Boolean

Returns true if a record exists in the table that matches the id or conditions given, or false otherwise.
#fifth

Find the fifth record.
#fifth!

Same as #fifth but raises RecordNotFound if no record is found.
#find(*args)

Find by id - This can either be a specific id (ID), a list of ids (ID, ID, ID), or an array of ids ([ID, ID, ID]).
#find_by(arg, *args)

Finds the first record matching the specified conditions.
#find_by!(arg, *args)

Like #find_by, except that if no record is found, raises an RecordNotFound error.
#find_sole_by(arg, *args)

Finds the sole matching record.
#first(limit = nil)

Find the first record (or first N records if a parameter is supplied).
#first!

Same as #first but raises RecordNotFound if no record is found.
#forty_two

Find the forty-second record.
#forty_two!

Same as #forty_two but raises RecordNotFound if no record is found.
#fourth

Find the fourth record.
#fourth!

Same as #fourth but raises RecordNotFound if no record is found.
#include?(record) ⇒ Boolean (also: #member?)

Returns true if the relation contains the given record or false otherwise.
#last(limit = nil)

Find the last record (or last N records if a parameter is supplied).
#last!

Same as #last but raises RecordNotFound if no record is found.
#member?(record)

Alias for #include?.
#second

Find the second record.
#second!

Same as #second but raises RecordNotFound if no record is found.
#second_to_last

Find the second-to-last record.
#second_to_last!

Same as #second_to_last but raises RecordNotFound if no record is found.
#sole

Finds the sole matching record.
#take(limit = nil)

Gives a record (or N records if a parameter is supplied) without any implied order.
#take!

Same as #take but raises RecordNotFound if no record is found.
#third

Find the third record.
#third!

Same as #third but raises RecordNotFound if no record is found.
#third_to_last

Find the third-to-last record.
#third_to_last!

Same as #third_to_last but raises RecordNotFound if no record is found.
#_order_columns private
#apply_join_dependency(eager_loading: group_values.empty?) private
#construct_relation_for_exists(conditions) private
#find_last(limit) private
#find_nth(index) private
#find_nth_from_last(index) private
#find_nth_with_limit(index, limit) private
#find_one(id) private
#find_some(ids) private
#find_some_ordered(ids) private
#find_take private
#find_take_with_limit(limit) private
#find_with_ids(*ids) private
#ordered_relation private
#using_limitable_reflections?(reflections) ⇒ Boolean private
#raise_record_not_found_exception!(ids = nil, result_size = nil, expected_size = nil, key = primary_key, not_found_ids = nil) Internal use only

This method is called whenever no records are found with either a single id or multiple ids and raises an RecordNotFound exception.

Instance Method Details

#_order_columns (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 648


def _order_columns
  oc = []

  oc << implicit_order_column if implicit_order_column
  oc << query_constraints_list if query_constraints_list

  if primary_key && query_constraints_list.nil?
    oc << primary_key
  end

  oc.flatten.uniq.compact
end

#apply_join_dependency(eager_loading: group_values.empty?) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 457


def apply_join_dependency(eager_loading: group_values.empty?)
  join_dependency = construct_join_dependency(
    eager_load_values | includes_values, Arel::Nodes::OuterJoin
  )
  relation = except(:includes, :eager_load, :preload).joins!(join_dependency)

  if eager_loading && has_limit_or_offset? && !(
      using_limitable_reflections?(join_dependency.reflections) &&
      using_limitable_reflections?(
        construct_join_dependency(
          select_association_list(joins_values).concat(
            select_association_list(left_outer_joins_values)
          ), nil
        ).reflections
      )
    )
    relation = skip_query_cache_if_necessary do
      klass.with_connection do |c|
        c.distinct_relation_for_primary_key(relation)
      end
    end
  end

  if block_given?
    yield relation, join_dependency
  else
    relation
  end
end

#construct_relation_for_exists(conditions) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 438


def construct_relation_for_exists(conditions)
  conditions = sanitize_forbidden_attributes(conditions)

  if distinct_value && offset_value
    relation = except(:order).limit!(1)
  else
    relation = except(:select, :distinct, :order)._select!(ONE_AS_ONE).limit!(1)
  end

  case conditions
  when Array, Hash
    relation.where!(conditions) unless conditions.empty?
  else
    relation.where!(primary_key => conditions) unless conditions == :none
  end

  relation
end

#exists?(conditions = :none) ⇒ `Boolean`

Returns true if a record exists in the table that matches the id or conditions given, or false otherwise. The argument can take six 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 where-style conditions (such as ['name LIKE ?', "%#{query}%"]).
::Hash - Finds the record that matches these where-style conditions (such as {name: 'David'}).
false - Returns always false.
No args - Returns false if the relation is empty, true otherwise.

For more information about specifying conditions as a hash or array, see the Conditions section in the introduction to 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\''.

Person.exists?(5)
Person.exists?('5')
Person.exists?(['name LIKE ?', "%#{query}%"])
Person.exists?(id: [1, 4, 8])
Person.exists?(name: 'David')
Person.exists?(false)
Person.exists?
Person.where(name: 'Spartacus', rating: 4).exists?

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 357


def exists?(conditions = :none)
  return false if @none

  if Base === conditions
    raise ArgumentError, <<-MSG.squish
      You are passing an instance of ActiveRecord::Base to `exists?`.
      Please pass the id of the object by calling `.id`.
    MSG
  end

  return false if !conditions || limit_value == 0

  if eager_loading?
    relation = apply_join_dependency(eager_loading: false)
    return relation.exists?(conditions)
  end

  relation = construct_relation_for_exists(conditions)
  return false if relation.where_clause.contradiction?

  skip_query_cache_if_necessary do
    with_connection do |c|
      c.select_rows(relation.arel, "#{name} Exists?").size == 1
    end
  end
end

#fifth

Find the fifth record. If no order is defined it will order by primary key.

Person.fifth # returns the fifth object fetched by SELECT * FROM people
Person.offset(3).fifth # returns the fifth object from OFFSET 3 (which is OFFSET 7)
Person.where(["user_name = :u", { u: user_name }]).fifth

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 271


def fifth
  find_nth 4
end

#fifth!

Same as #fifth but raises RecordNotFound if no record is found.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 277


def fifth!
  fifth || raise_record_not_found_exception!
end

#find(*args)

Find by id - This can either be a specific id (ID), a list of ids (ID, ID, ID), or an array of ids ([ID, ID, ID]). ID refers to an “identifier”. For models with a single-column primary key, ID will be a single value, and for models with a composite primary key, it will be an array of values. If one or more records cannot be found for the requested ids, then RecordNotFound will be raised. If the primary key is an integer, find by id coerces its arguments by using to_i.

Person.find(1)          # returns the object for ID = 1
Person.find("1")        # returns the object for ID = 1
Person.find("31-sarah") # returns the object for ID = 31
Person.find(1, 2, 6)    # returns an array for objects with IDs in (1, 2, 6)
Person.find([7, 17])    # returns an array for objects with IDs in (7, 17), or with composite primary key [7, 17]
Person.find([1])        # returns an array for the object with ID = 1
Person.where("administrator = 1").order("created_on DESC").find(1)

Find a record for a composite primary key model

TravelRoute.primary_key = [:origin, :destination]

TravelRoute.find(["Ottawa", "London"])
#=> #<TravelRoute origin: "Ottawa", destination: "London">

TravelRoute.find([["Paris", "Montreal"]])
#=> [#<TravelRoute origin: "Paris", destination: "Montreal">]

TravelRoute.find(["New York", "Las Vegas"], ["New York", "Portland"])
#=> [
     #<TravelRoute origin: "New York", destination: "Las Vegas">,
     #<TravelRoute origin: "New York", destination: "Portland">
   ]

TravelRoute.find([["Berlin", "London"], ["Barcelona", "Lisbon"]])
#=> [
     #<TravelRoute origin: "Berlin", destination: "London">,
     #<TravelRoute origin: "Barcelona", destination: "Lisbon">
   ]

NOTE: The returned records are in the same order as the ids you provide. If you want the results to be sorted by database, you can use QueryMethods#where method and provide an explicit QueryMethods#order option. But QueryMethods#where method doesn’t raise RecordNotFound.

Find with lock

Example for find with a lock: Imagine two concurrent transactions: each will read person.visits == 2, add 1 to it, and save, resulting in two saves of person.visits = 3. By locking the row, the second transaction has to wait until the first is finished; we get the expected person.visits == 4.

Person.transaction do
  person = Person.lock(true).find(1)
  person.visits += 1
  person.save!
end

Variations of `#find`

Person.where(name: 'Spartacus', rating: 4)
# returns a chainable list (which can be empty).

Person.find_by(name: 'Spartacus', rating: 4)
# returns the first item or nil.

Person.find_or_initialize_by(name: 'Spartacus', rating: 4)
# returns the first item or returns a new instance (requires you call .save to persist against the database).

Person.find_or_create_by(name: 'Spartacus', rating: 4)
# returns the first item or creates it and returns it.

Alternatives for `#find`

Person.where(name: 'Spartacus', rating: 4).exists?(conditions = :none)
# returns a boolean indicating if any record with the given conditions exist.

Person.where(name: 'Spartacus', rating: 4).select("field1, field2, field3")
# returns a chainable list of instances with only the mentioned fields.

Person.where(name: 'Spartacus', rating: 4).ids
# returns an Array of ids.

Person.where(name: 'Spartacus', rating: 4).pluck(:field1, :field2)
# returns an Array of the required fields.

Edge Cases

Person.find(37)          # raises ActiveRecord::RecordNotFound exception if the record with the given ID does not exist.
Person.find([37])        # raises ActiveRecord::RecordNotFound exception if the record with the given ID in the input array does not exist.
Person.find(nil)         # raises ActiveRecord::RecordNotFound exception if the argument is nil.
Person.find([])          # returns an empty array if the argument is an empty array.
Person.find              # raises ActiveRecord::RecordNotFound exception if the argument is not provided.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 98


def find(*args)
  return super if block_given?
  find_with_ids(*args)
end

#find_by(arg, *args)

Finds the first record matching the specified conditions. There is no implied ordering so if order matters, you should specify it yourself.

If no record is found, returns nil.

Post.find_by name: 'Spartacus', rating: 4
Post.find_by "published_at < ?", 2.weeks.ago

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 111


def find_by(arg, *args)
  where(arg, *args).take
end

#find_by!(arg, *args)

Like #find_by, except that if no record is found, raises an RecordNotFound error.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 117


def find_by!(arg, *args)
  where(arg, *args).take!
end

#find_last(limit) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 636


def find_last(limit)
  limit ? records.last(limit) : records.last
end

#find_nth(index) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 598


def find_nth(index)
  @offsets ||= {}
  @offsets[index] ||= find_nth_with_limit(index, 1).first
end

#find_nth_from_last(index) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 622


def find_nth_from_last(index)
  if loaded?
    records[-index]
  else
    relation = ordered_relation

    if relation.order_values.empty? || relation.has_limit_or_offset?
      relation.records[-index]
    else
      relation.reverse_order.offset(index - 1).first
    end
  end
end

#find_nth_with_limit(index, limit) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 603


def find_nth_with_limit(index, limit)
  if loaded?
    records[index, limit] || []
  else
    relation = ordered_relation

    if limit_value
      limit = [limit_value - index, limit].min
    end

    if limit > 0
      relation = relation.offset((offset_value || 0) + index) unless index.zero?
      relation.limit(limit).to_a
    else
      []
    end
  end
end

#find_one(id) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 520


def find_one(id)
  if ActiveRecord::Base === id
    raise ArgumentError, <<-MSG.squish
      You are passing an instance of ActiveRecord::Base to `find`.
      Please pass the id of the object by calling `.id`.
    MSG
  end

  relation = if klass.composite_primary_key?
    where(primary_key.zip(id).to_h)
  else
    where(primary_key => id)
  end

  record = relation.take

  raise_record_not_found_exception!(id, 0, 1) unless record

  record
end

#find_sole_by(arg, *args)

Finds the sole matching record. Raises RecordNotFound if no record is found. Raises SoleRecordExceeded if more than one record is found.

Product.find_sole_by(["price = %?", price])

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 160


def find_sole_by(arg, *args)
  where(arg, *args).sole
end

#find_some(ids) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 541


def find_some(ids)
  return find_some_ordered(ids) unless order_values.present?

  relation = where(primary_key => ids)
  relation = relation.select(table[primary_key]) unless select_values.empty?
  result = relation.to_a

  expected_size =
    if limit_value && ids.size > limit_value
      limit_value
    else
      ids.size
    end

  # 11 ids with limit 3, offset 9 should give 2 results.
  if offset_value && (ids.size - offset_value < expected_size)
    expected_size = ids.size - offset_value
  end

  if result.size == expected_size
    result
  else
    raise_record_not_found_exception!(ids, result.size, expected_size)
  end
end

#find_some_ordered(ids) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 567


def find_some_ordered(ids)
  ids = ids.slice(offset_value || 0, limit_value || ids.size) || []

  relation = except(:limit, :offset)
  relation = relation.where(primary_key => ids)
  relation = relation.select(table[primary_key]) unless select_values.empty?
  result = relation.records

  if result.size == ids.size
    result.in_order_of(:id, ids.map { |id| @klass.type_for_attribute(primary_key).cast(id) })
  else
    raise_record_not_found_exception!(ids, result.size, ids.size)
  end
end

#find_take (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 582


def find_take
  if loaded?
    records.first
  else
    @take ||= limit(1).records.first
  end
end

#find_take_with_limit(limit) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 590


def find_take_with_limit(limit)
  if loaded?
    records.take(limit)
  else
    limit(limit).to_a
  end
end

#find_with_ids(*ids) (private)

Raises:

(UnknownPrimaryKey)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 491


def find_with_ids(*ids)
  raise UnknownPrimaryKey.new(@klass) if primary_key.nil?

  expects_array = if klass.composite_primary_key?
    ids.first.first.is_a?(Array)
  else
    ids.first.is_a?(Array)
  end

  return [] if expects_array && ids.first.empty?

  ids = ids.first if expects_array

  ids = ids.compact.uniq

  model_name = @klass.name

  case ids.size
  when 0
    error_message = "Couldn't find #{model_name} without an ID"
    raise RecordNotFound.new(error_message, model_name, primary_key)
  when 1
    result = find_one(ids.first)
    expects_array ? [ result ] : result
  else
    find_some(ids)
  end
end

#first(limit = nil)

Find the first record (or first N records if a parameter is supplied). If no order is defined it will order by primary key.

Person.first # returns the first object fetched by SELECT * FROM people ORDER BY people.id LIMIT 1
Person.where(["user_name = ?", user_name]).first
Person.where(["user_name = :u", { u: user_name }]).first
Person.order("created_on DESC").offset(5).first
Person.first(3) # returns the first three objects fetched by SELECT * FROM people ORDER BY people.id LIMIT 3

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 173


def first(limit = nil)
  if limit
    find_nth_with_limit(0, limit)
  else
    find_nth 0
  end
end

#first!

Same as #first but raises RecordNotFound if no record is found. Note that #first! accepts no arguments.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 183


def first!
  first || raise_record_not_found_exception!
end

#forty_two

Find the forty-second record. Also known as accessing “the reddit”. If no order is defined it will order by primary key.

Person.forty_two # returns the forty-second object fetched by SELECT * FROM people
Person.offset(3).forty_two # returns the forty-second object from OFFSET 3 (which is OFFSET 44)
Person.where(["user_name = :u", { u: user_name }]).forty_two

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 287


def forty_two
  find_nth 41
end

#forty_two!

Same as #forty_two but raises RecordNotFound if no record is found.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 293


def forty_two!
  forty_two || raise_record_not_found_exception!
end

#fourth

Find the fourth record. If no order is defined it will order by primary key.

Person.fourth # returns the fourth object fetched by SELECT * FROM people
Person.offset(3).fourth # returns the fourth object from OFFSET 3 (which is OFFSET 6)
Person.where(["user_name = :u", { u: user_name }]).fourth

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 255


def fourth
  find_nth 3
end

#fourth!

Same as #fourth but raises RecordNotFound if no record is found.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 261


def fourth!
  fourth || raise_record_not_found_exception!
end

#include?(record) ⇒ `Boolean` Also known as: #member?

Returns true if the relation contains the given record or false otherwise.

No query is performed if the relation is loaded; the given record is compared to the records in memory. If the relation is unloaded, an efficient existence query is performed, as in #exists?.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 389


def include?(record)
  # The existing implementation relies on receiving an Active Record instance as the input parameter named record.
  # Any non-Active Record object passed to this implementation is guaranteed to return `false`.
  return false unless record.is_a?(klass)

  if loaded? || offset_value || limit_value || having_clause.any?
    records.include?(record)
  else
    id = if record.class.composite_primary_key?
      record.class.primary_key.zip(record.id).to_h
    else
      record.id
    end

    exists?(id)
  end
end

#last(limit = nil)

Find the last record (or last N records if a parameter is supplied). If no order is defined it will order by primary key.

Person.last # returns the last object fetched by SELECT * FROM people
Person.where(["user_name = ?", user_name]).last
Person.order("created_on DESC").offset(5).last
Person.last(3) # returns the last three objects fetched by SELECT * FROM people.

Take note that in that last case, the results are sorted in ascending order:

[#<Person id:2>, #<Person id:3>, #<Person id:4>]

and not:

[#<Person id:4>, #<Person id:3>, #<Person id:2>]

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 202


def last(limit = nil)
  return find_last(limit) if loaded? || has_limit_or_offset?

  result = ordered_relation.limit(limit)
  result = result.reverse_order!

  limit ? result.reverse : result.first
end

#last!

Same as #last but raises RecordNotFound if no record is found. Note that #last! accepts no arguments.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 213


def last!
  last || raise_record_not_found_exception!
end

#member?(record)

Alias for #include?.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 407


alias :member? :include?

#ordered_relation (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 640


def ordered_relation
  if order_values.empty? && (implicit_order_column || !query_constraints_list.nil? || primary_key)
    order(_order_columns.map { |column| table[column].asc })
  else
    self
  end
end

#raise_record_not_found_exception!(ids = nil, result_size = nil, expected_size = nil, key = primary_key, not_found_ids = nil)

This method is for internal use only.

This method is called whenever no records are found with either a single id or multiple ids and raises an RecordNotFound exception.

The error message is different depending on whether a single id or multiple ids are provided. If multiple ids are provided, then the number of results obtained should be provided in the result_size argument and the expected number of results should be provided in the expected_size argument.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 417


def raise_record_not_found_exception!(ids = nil, result_size = nil, expected_size = nil, key = primary_key, not_found_ids = nil) # :nodoc:
  conditions = " [#{arel.where_sql(klass)}]" unless where_clause.empty?

  name = @klass.name

  if ids.nil?
    error = +"Couldn't find #{name}"
    error << " with#{conditions}" if conditions
    raise RecordNotFound.new(error, name, key)
  elsif Array.wrap(ids).size == 1
    error = "Couldn't find #{name} with '#{key}'=#{ids}#{conditions}"
    raise RecordNotFound.new(error, name, key, ids)
  else
    error = +"Couldn't find all #{name.pluralize} with '#{key}': "
    error << "(#{ids.join(", ")})#{conditions} (found #{result_size} results, but was looking for #{expected_size})."
    error << " Couldn't find #{name.pluralize(not_found_ids.size)} with #{key.to_s.pluralize(not_found_ids.size)} #{not_found_ids.join(', ')}." if not_found_ids
    raise RecordNotFound.new(error, name, key, ids)
  end
end

#second

Find the second record. If no order is defined it will order by primary key.

Person.second # returns the second object fetched by SELECT * FROM people
Person.offset(3).second # returns the second object from OFFSET 3 (which is OFFSET 4)
Person.where(["user_name = :u", { u: user_name }]).second

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 223


def second
  find_nth 1
end

#second!

Same as #second but raises RecordNotFound if no record is found.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 229


def second!
  second || raise_record_not_found_exception!
end

#second_to_last

Find the second-to-last record. If no order is defined it will order by primary key.

Person.second_to_last # returns the second-to-last object fetched by SELECT * FROM people
Person.offset(3).second_to_last # returns the second-to-last object from OFFSET 3
Person.where(["user_name = :u", { u: user_name }]).second_to_last

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 319


def second_to_last
  find_nth_from_last 2
end

#second_to_last!

Same as #second_to_last but raises RecordNotFound if no record is found.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 325


def second_to_last!
  second_to_last || raise_record_not_found_exception!
end

#sole

Finds the sole matching record. Raises RecordNotFound if no record is found. Raises SoleRecordExceeded if more than one record is found.

Product.where(["price = %?", price]).sole

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 143


def sole
  found, undesired = first(2)

  if found.nil?
    raise_record_not_found_exception!
  elsif undesired.present?
    raise ActiveRecord::SoleRecordExceeded.new(self)
  else
    found
  end
end

#take(limit = nil)

Gives a record (or N records if a parameter is supplied) without any implied order. The order will depend on the database implementation. If an order is supplied it will be respected.

Person.take # returns an object fetched by SELECT * FROM people LIMIT 1
Person.take(5) # returns 5 objects fetched by SELECT * FROM people LIMIT 5
Person.where(["name LIKE '%?'", name]).take

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 128


def take(limit = nil)
  limit ? find_take_with_limit(limit) : find_take
end

#take!

Same as #take but raises RecordNotFound if no record is found. Note that #take! accepts no arguments.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 134


def take!
  take || raise_record_not_found_exception!
end

#third

Find the third record. If no order is defined it will order by primary key.

Person.third # returns the third object fetched by SELECT * FROM people
Person.offset(3).third # returns the third object from OFFSET 3 (which is OFFSET 5)
Person.where(["user_name = :u", { u: user_name }]).third

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 239


def third
  find_nth 2
end

#third!

Same as #third but raises RecordNotFound if no record is found.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 245


def third!
  third || raise_record_not_found_exception!
end

#third_to_last

Find the third-to-last record. If no order is defined it will order by primary key.

Person.third_to_last # returns the third-to-last object fetched by SELECT * FROM people
Person.offset(3).third_to_last # returns the third-to-last object from OFFSET 3
Person.where(["user_name = :u", { u: user_name }]).third_to_last

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 303


def third_to_last
  find_nth_from_last 3
end

#third_to_last!

Same as #third_to_last but raises RecordNotFound if no record is found.

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 309


def third_to_last!
  third_to_last || raise_record_not_found_exception!
end

#using_limitable_reflections?(reflections) ⇒ `Boolean` (private)

[ GitHub ]

# File 'activerecord/lib/active_record/relation/finder_methods.rb', line 487


def using_limitable_reflections?(reflections)
  reflections.none?(&:collection?)
end

Module: ActiveRecord::FinderMethods

Constant Summary

Instance Method Summary

Instance Method Details

#_order_columns (private)

#apply_join_dependency(eager_loading: group_values.empty?) (private)

#construct_relation_for_exists(conditions) (private)

#exists?(conditions = :none) ⇒ Boolean

#fifth

#fifth!

#find(*args)

Find a record for a composite primary key model

Find with lock

Variations of #find

Alternatives for #find

Edge Cases

#find_by(arg, *args)

#find_by!(arg, *args)

#find_last(limit) (private)

#find_nth(index) (private)

#find_nth_from_last(index) (private)

#find_nth_with_limit(index, limit) (private)

#find_one(id) (private)

#find_sole_by(arg, *args)

#find_some(ids) (private)

#find_some_ordered(ids) (private)

#find_take (private)

#find_take_with_limit(limit) (private)

#find_with_ids(*ids) (private)

#first(limit = nil)

#first!

#forty_two

#forty_two!

#fourth

#fourth!

#include?(record) ⇒ Boolean Also known as: #member?

#last(limit = nil)

#last!

#member?(record)

#ordered_relation (private)

#raise_record_not_found_exception!(ids = nil, result_size = nil, expected_size = nil, key = primary_key, not_found_ids = nil)

#second

#second!

#second_to_last

#second_to_last!

#sole

#take(limit = nil)

#take!

#third

#third!

#third_to_last

#third_to_last!

#using_limitable_reflections?(reflections) ⇒ Boolean (private)

#exists?(conditions = :none) ⇒ `Boolean`

Variations of `#find`

Alternatives for `#find`

#include?(record) ⇒ `Boolean` Also known as: #member?

#using_limitable_reflections?(reflections) ⇒ `Boolean` (private)