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document edge cases in AR calculations, and wrap some comments

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This commit is contained in:
Xavier Noria 2008-12-30 02:45:23 +01:00
parent 477d37a0fb
commit 9c3c88a894
1 changed files with 16 additions and 8 deletions
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24
activerecord/lib/active_record/calculations.rb
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@ -48,30 +48,38 @@ module ActiveRecord
calculate(:count, *construct_count_options_from_args(*args))
end
# Calculates the average value on a given column. The value is returned as a float. See +calculate+ for examples with options.
# Calculates the average value on a given column. The value is returned as
# a float, or +nil+ if there's no row. See +calculate+ for examples with
# options.
#
# Person.average('age')
# Person.average('age') # => 35.8
def average(column_name, options = {})
calculate(:avg, column_name, options)
end
# Calculates the minimum value on a given column. The value is returned with the same data type of the column. See +calculate+ for examples with options.
# Calculates the minimum value on a given column. The value is returned
# with the same data type of the column, or +nil+ if there's no row. See
# +calculate+ for examples with options.
#
# Person.minimum('age')
# Person.minimum('age') # => 7
def minimum(column_name, options = {})
calculate(:min, column_name, options)
end
# Calculates the maximum value on a given column. The value is returned with the same data type of the column. See +calculate+ for examples with options.
# Calculates the maximum value on a given column. The value is returned
# with the same data type of the column, or +nil+ if there's no row. See
# +calculate+ for examples with options.
#
# Person.maximum('age')
# Person.maximum('age') # => 93
def maximum(column_name, options = {})
calculate(:max, column_name, options)
end
# Calculates the sum of values on a given column. The value is returned with the same data type of the column. See +calculate+ for examples with options.
# Calculates the sum of values on a given column. The value is returned
# with the same data type of the column, 0 if there's no row. See
# +calculate+ for examples with options.
#
# Person.sum('age')
# Person.sum('age') # => 4562
def sum(column_name, options = {})
calculate(:sum, column_name, options)
end