rails - count records by value

Question

I am trying to group records based on a value from a column, so I can use it to display the information elsewhere. At the moment I have this working if I specify the values in the column -

@city_count = People.select('city,count(*)').where("city in ('london', 'paris')").group(:city).count

This works fine if I want a list of people in London and Paris but if the city list also has Sydney, New York, Rio etc I don't want to keep adding the extra cities to the 'city in', I would like this to just find the people selected by each city.

Does anyone know the best way of doing this? Also if it can include NULL values as well.

Answer 1

Just use:

@city_count = People.group(:city).count

to get counts for all cities. This will include an entry for nil.