Yet another "NameError: uninitialized constant" problem

rubyonrails-talk
1

I've searched for information about this and compared what I have to the solutions I can find, here and elsewhere. I found some good and useful information, yet my stuff still doesn't work. I was hoping somebody here could spot something. I'm using rails 2.1.2 and I'm pretty new to ruby and rails.

My goal is a fairly simple many-to-many relationship linking "modules" and "users". There's 3 tables (I know the names are inconsistent - it's a little strange because it was an existing database that I dumped into rails): - module: a module definition - users: the users of the system - module_user_map: join table linking modules and users

My data model (from schema.rb) looks in part like this: create_table "module", :force => true do |t|     t.string "name", :default => "", :null => false     t.integer "status", :default => 0, :null => false     ... end

create_table "module_user_map", :force => true do |t|     t.integer "module", :default => 0, :null => false     t.integer "user", :default => 0, :null => false     ... end

create_table "users", :force => true do |t|     t.string "first_name", :limit => 45     t.string "last_name", :limit => 45     t.string "login", :limit => 45     ... end

Here's the corresponding files in app/models directory. It appears that I could not use "module" as the model name because that is a reserved word in rails, so I had to prepend "project_" to the "module" names. This might be where I messed up, I don't know.

=============== project_module.rb =================== class ProjectModule < ActiveRecord::Base   set_table_name "module"   has_many :module_user_maps, :dependent => :delete_all   has_many :users, :through => :module_user_maps end

=============== user.rb =================== class User < ActiveRecord::Base   has_many :module_user_maps, :dependent => :delete_all   has_many :project_modules, :through => :module_user_maps end

=============== module_user_maps.rb =================== class ModuleUserMaps < ActiveRecord::Base   set_table_name "module_user_map"   belongs_to :user   belongs_to :project_module end

So I run from the script/console (same thing happens in the server):

u=User.find(2)

=> #<User id: 2, first_name: "Site", last_name: "User", login: "user", password: "password", organization: 2, roles: "public", last_modified: "2008-11-17 12:09: 10", last_modified_by: nil, last_login: "2008-11-17 12:10:06", status: 1, date_c reated: nil, address1: nil, address2: nil, city: nil, state: nil, postal_code: n il, email: nil>

u.project_modules

NameError: uninitialized constant User::ModuleUserMap         from C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.2/lib/active_suppo rt/dependencies.rb:493:in `const_missing' ... etc ...

u.module_user_maps

NameError: uninitialized constant User::ModuleUserMap         from C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.2/lib/active_suppo rt/dependencies.rb:493:in `const_missing'         from C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record /base.rb:1914:in `compute_type' ... etc ...

I'm hoping somebody can spot something fairly simple. This should not be a hard thing to do. Thanks!

2

Hi Gary,

Gary Bisaga wrote:

=============== module_user_maps.rb =================== class ModuleUserMaps < ActiveRecord::Base   set_table_name "module_user_map"   belongs_to :user   belongs_to :project_module end

So I run from the script/console (same thing happens in the server):

NameError: uninitialized constant User::ModuleUserMap

I think if you change the class name to singular (and the file name) you'll be good to go.

Best regards, Bill

3

Hallelujah! You are a lifesaver Bill - you got me almost all the way home. At least, now it is giving me an error message that is actually useful in figuring out what the problem is:

ActiveRecord::StatementInvalid: Mysql::Error: #42S22Unknown column 'module_user_ map.user_id' in 'where clause': SELECT `module`.* FROM `module` INNER JOIN mo dule_user_map ON module.id = module_user_map.project_module_id WHERE ((`modul e_user_map`.user_id = 2))

So, after adding a few :foreign_key declarations like this:

class ModuleUserMap < ActiveRecord::Base   set_table_name "module_user_map"   belongs_to :user, :foreign_key => "user"   belongs_to :project_module, :foreign_key => "module" end

we're good. Thank you so much! It would be great if this gave better error messages.

<>< gary

Bill Walton wrote:

4

Hi Gary,

Gary Bisaga wrote:

we're good. Thank you so much!

You're very welcome. Glad to help.

Best regards, Bill