module DataMapper
module AggregateFunctions
# Count results (given the conditions)
#
# @example the count of all friends
# Friend.count
#
# @example the count of all friends older then 18
# Friend.count(:age.gt => 18)
#
# @example the count of all your female friends
# Friend.count(:conditions => [ 'gender = ?', 'female' ])
#
# @example the count of all friends with an address (NULL values are not included)
# Friend.count(:address)
#
# @example the count of all friends with an address that are older then 18
# Friend.count(:address, :age.gt => 18)
#
# @example the count of all your female friends with an address
# Friend.count(:address, :conditions => [ 'gender = ?', 'female' ])
#
# @param property [Symbol] of the property you with to count (optional)
# @param opts [Hash, Symbol] the conditions
#
# @return [Integer] return the count given the conditions
#
# @api public
def count(*args)
query = args.last.kind_of?(Hash) ? args.pop : {}
property_name = args.first
if property_name
assert_kind_of 'property', property_by_name(property_name), Property
end
aggregate(query.merge(:fields => [ property_name ? property_name.count : :all.count ]))
end
# Get the lowest value of a property
#
# @example the age of the youngest friend
# Friend.min(:age)
#
# @example the age of the youngest female friend
# Friend.min(:age, :conditions => [ 'gender = ?', 'female' ])
#
# @param property [Symbol] the property you wish to get the lowest value of
# @param opts [Hash, Symbol] the conditions
#
# @return [Integer] return the lowest value of a property given the conditions
#
# @api public
def min(*args)
query = args.last.kind_of?(Hash) ? args.pop : {}
property_name = args.first
assert_property_type property_name, Integer, Float, BigDecimal, DateTime, Date, Time
aggregate(query.merge(:fields => [ property_name.min ]))
end
# Get the highest value of a property
#
# @example the age of the oldest friend
# Friend.max(:age)
#
# @example the age of the oldest female friend
# Friend.max(:age, :conditions => [ 'gender = ?', 'female' ])
#
# @param property [Symbol] the property you wish to get the highest value of
# @param opts [Hash, Symbol] the conditions
#
# @return [Integer] return the highest value of a property given the conditions
#
# @api public
def max(*args)
query = args.last.kind_of?(Hash) ? args.pop : {}
property_name = args.first
assert_property_type property_name, Integer, Float, BigDecimal, DateTime, Date, Time
aggregate(query.merge(:fields => [ property_name.max ]))
end
# Get the average value of a property
#
# @example the average age of all friends
# Friend.avg(:age)
#
# @example the average age of all female friends
# Friend.avg(:age, :conditions => [ 'gender = ?', 'female' ])
#
# @param property [Symbol] the property you wish to get the average value of
# @param opts [Hash, Symbol] the conditions
#
# @return [Integer] return the average value of a property given the conditions
#
# @api public
def avg(*args)
query = args.last.kind_of?(Hash) ? args.pop : {}
property_name = args.first
assert_property_type property_name, Integer, Float, BigDecimal
aggregate(query.merge(:fields => [ property_name.avg ]))
end
# Get the total value of a property
#
# @example the total age of all friends
# Friend.sum(:age)
#
# @example the total age of all female friends
# Friend.max(:age, :conditions => [ 'gender = ?', 'female' ])
#
# @param property [Symbol] the property you wish to get the total value of
# @param opts [Hash, Symbol] the conditions
#
# @return [Integer] return the total value of a property given the conditions
#
# @api public
def sum(*args)
query = args.last.kind_of?(Hash) ? args.pop : {}
property_name = args.first
assert_property_type property_name, Integer, Float, BigDecimal
aggregate(query.merge(:fields => [ property_name.sum ]))
end
# Perform aggregate queries
#
# @example the count of friends
# Friend.aggregate(:all.count)
#
# @example the minimum age, the maximum age and the total age of friends
# Friend.aggregate(:age.min, :age.max, :age.sum)
#
# @example the average age, grouped by gender
# Friend.aggregate(:age.avg, :fields => [ :gender ])
#
# @param aggregates [Symbol, ...] operators to aggregate with
# @params query [Hash] the conditions
#
# @return [Array,Numeric,DateTime,Date,Time] the results of the
# aggregate query
#
# @api public
def aggregate(*args)
query = args.last.kind_of?(Hash) ? args.pop : {}
query[:fields] ||= []
query[:fields] |= args
query[:fields].map! { |f| normalize_field(f) }
query[:order] ||= query[:fields].select { |p| p.kind_of?(Property) }
raise ArgumentError, 'query[:fields] must not be empty' if query[:fields].empty?
query = scoped_query(query)
if query.fields.any? { |p| p.kind_of?(Property) }
query.repository.aggregate(query.update(:unique => true))
else
query.repository.aggregate(query).first # only return one row
end
end
private
def assert_property_type(name, *types)
if name.nil?
raise ArgumentError, 'property name must not be nil'
end
type = property_by_name(name).type
unless types.include?(type)
raise ArgumentError, "#{name} must be #{types * ' or '}, but was #{type}"
end
end
def normalize_field(field)
assert_kind_of 'field', field, Query::Operator, Symbol, Property
case field
when Query::Operator
if field.target == :all
field
else
field.class.new(property_by_name(field.target), field.operator)
end
when Symbol
property_by_name(field)
when Property
field
end
end
end
end
