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author | Xavier Noria <fxn@hashref.com> | 2008-12-30 02:45:23 +0100 |
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committer | Xavier Noria <fxn@hashref.com> | 2008-12-30 02:45:23 +0100 |
commit | 9c3c88a894cb76a8f753c12fd22f66e3c9d5fe08 (patch) | |
tree | 9dec0f5e1ca1aca133fcb7cf057dd5811fd645e2 /activerecord/lib | |
parent | 477d37a0fbc7bfe31f8b83050e36d310ed19fb2a (diff) | |
download | rails-9c3c88a894cb76a8f753c12fd22f66e3c9d5fe08.tar.gz rails-9c3c88a894cb76a8f753c12fd22f66e3c9d5fe08.tar.bz2 rails-9c3c88a894cb76a8f753c12fd22f66e3c9d5fe08.zip |
document edge cases in AR calculations, and wrap some comments
Diffstat (limited to 'activerecord/lib')
-rw-r--r-- | activerecord/lib/active_record/calculations.rb | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/activerecord/lib/active_record/calculations.rb b/activerecord/lib/active_record/calculations.rb index 65512d534a..b239c03284 100644 --- a/activerecord/lib/active_record/calculations.rb +++ b/activerecord/lib/active_record/calculations.rb @@ -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 |