Rails: How to list database tables/objects using the Rails console?

You can use rails dbconsole to view the database that your rails application is using. It's alternative answer rails db. Both commands will direct you the command line interface and will allow you to use that database query syntax.

You are probably seeking:

ActiveRecord::Base.connection.tables

and

ActiveRecord::Base.connection.columns('projects').map(&:name)

You should probably wrap them in shorter syntax inside your .irbrc.

I hope my late answer can be of some help.
This will go to rails database console.

rails db

pretty print your query output

.headers on
.mode columns
(turn headers on and show database data in column mode )

Show the tables

.table

'.help' to see help.
Or use SQL statements like 'Select * from cars'

To get a list of all model classes, you can use ActiveRecord::Base.subclasses e.g.

ActiveRecord::Base.subclasses.map { |cl| cl.name }
ActiveRecord::Base.subclasses.find { |cl| cl.name == "Foo" }