MongoMapper query for not null column.

gistfile1.md

Goal

"Using MongoMapper to find all users that :name column is not null", this is all I want.

Solution

To do so, use this query:

User.where(:name.ne => nil).all
User.all(:name.ne => nil)

My mistakes:

User.where(:name.ne => nil)

See? If you don't contact with all explicitly, you fail. This is different from Rails ActiveRecord.

What is .ne?

ne means not equal. There are similar 'gt, lt, get, or' queries around.

You could get more information in http://www.mongodb.org/display/DOCS/Advanced+Queries

Other examples from mongo_mapper

/Users/username/.rvm/gems/ruby-1.9.2-p290/gems/mongo_mapper-0.10.1/examples/query.rb

User.all(:name => 'John')
User.all(:tags => %w[mongo])
User.all(:tags.all => %w[ruby mongo])
User.all(:age.gte => 30)

User.where(:age.gt => 27).sort(:age).all
User.where(:age.gt => 27).sort(:age.desc).all
User.where(:age.gt => 27).sort(:age).limit(1).all
User.where(:age.gt => 27).sort(:age).skip(1).limit(1).all

Nice, thanks!