Find ActiveRecord object by maximum field value of a child object?

Question

How can I find the object associated with the results of an ActiveRecord Calculation rather than a value?

For example I have @parent which has many children. I would lik

Answer 1

@parent.children.order("value DESC").first

Answer 2

Not sure if this is the most efficient but once you have the maximum value you can pass that along in a hash to get the object

@maxvalue = @parent.children.maximum(:value)
@myObject = @parent.children.where(:value => @maxvalue)

Answer 3

This is my personal favorite when it comes to readability, by using ruby's #max_by :

@parent.children.max_by(&:value)

Answer 4

@parent.children.first(:conditions => {:value => @parent.children.maximum(:value)})