Rails - Building Conditions for Use in a Query

Question

I usually like to build a conditions hash like this below:

conditions = {}
conditions[:color] = "black"
conditions[:doors] = 4
conditions[:type] = "sedan"

Cars.find(:all, :conditions=>conditions)

But how would I add a date range into this for something like:

year >= '2011-01-01' and year < '2011-02-01'

Answer 1

I am assuming you are using Rails 2.3.x and year is a date column.

conditions = {}
conditions[:color] = "black"
conditions[:doors] = 4
conditions[:type] = "sedan"
# create a date range
conditions[:year] = (Date.parse("2011-01-01")...Date.parse("2011-02-01"))

Car.all(:conditions => conditions)

If you want to do even more complex queries in 2.3.x use the AR Extensions gem. Read this article for more details.

Answer 2

You can build a up query through relations. The query will not be executed until it needs to be evaluated. This is nice for searches where some parameters are optional.

@cars = Cars.where(:color => "black")
@cars = @cars.where(:doors => 4)
@cars = @cars.where("year >= '2011-01-01'")
@cars = @cars.where("year <= '2011-02-01'")

Or you could just merge all that together into one:

Cars.where(["color=? AND doors=? AND year >= ? AND year <= ?", "black", 4, "2011-01-01", "2011-02-01"]

UPDATE: For Rails < 3

@cars = Cars.scoped(:conditions => {:color => "black"})
@cars = @cars.scoped(:conditions => {:doors => 4})
@cars = @cars.scoped(:conditions => "year >= '2011-01-01'")
@cars = @cars.scoped(:conditions => "year <= '2011-02-01'")

OR

Cars.all(:conditions => ["color=? AND doors=? AND year >= ? AND year <= ?", "black", 4, "2011-01-01", "2011-02-01"]

Answer 3

If you're on Rails 3, why not use AREL?

Cars.where(:color => "black").
     where(:doors => 4).
     where(:type => "sedan").
     where("year >= '2011-01-01'").
     where("year < '2011-02-01'")

Btw, don't use :type as a field name. Rails uses this for STI.

On Rails 2.3, I'd just build up conditions as a String instead.