activerecord find conditions for associated models - ruby-on-rails

Question

so i havent found much documentation about using conditions on activerecord find methods for associated models, but i have found a variety of examples. although none of them seem to be working for me.
user has_one avatar
avatar belongs_to user
Avatar.find(:all, :include => :user, :conditions => {:user => {:login => 'admin'}})
returns the ridiculously long error
SQLite3::SQLException: no such column: user.login: SELECT "avatars"."id" AS t0_r0, "avatars"."user_id" AS t0_r1, "avatars"."featured" AS t0_r2, "avatars"."avatar_file_name" AS t0_r3, "avatars"."avatar_content_type" AS t0_r4, "avatars"."avatar_file_size" AS t0_r5, "avatars"."created_at" AS t0_r6, "avatars"."updated_at" AS t0_r7, "users"."id" AS t1_r0, "users"."login" AS t1_r1, "users"."email" AS t1_r2, "users"."crypted_password" AS t1_r3, "users"."password_salt" AS t1_r4, "users"."persistence_token" AS t1_r5, "users"."perishable_token" AS t1_r6, "users"."login_count" AS t1_r7, "users"."failed_login_count" AS t1_r8, "users"."last_request_at" AS t1_r9, "users"."current_login_at" AS t1_r10, "users"."last_login_at" AS t1_r11, "users"."current_login_ip" AS t1_r12, "users"."last_login_ip" AS t1_r13, "users"."created_at" AS t1_r14, "users"."updated_at" AS t1_r15 FROM "avatars" LEFT OUTER JOIN "users" ON "users".id = "avatars".user_id WHERE ("user"."login" = 'admin')
i have tried a variety of other patterns including
:conditions => "user.login == 'admin'"
but nothing is working.
this is with a rails 2.3.8 app, but rails3 is installed as well. so i have activerecord 3.0.0 & 2.3.8 installed. i thought this may be an issue, but it seems unlikely.

Answer 1

instead of
:user => {:login => 'admin'}
try
:users => {:login => 'admin'}
users

Answer 2

The standard Rails format for table names in the database itself is "all lower case, plural."
So you can debug your SQL error and see:
no such column: user.login
Since we know the table name is "users" the problem is that you're referencing table "user"
Fix depends on the version of Active Record. I prefer old school since it makes it more clear that the condition clause is SQL, not Ruby/Rails:
Avatar.find(:all, :include => :user,
:conditions => "users.login = 'admin'")
Note: Rails 3 is different from the above...
Added:
Remember that if you're looking up a login supplied as a parameter from the user, you must properly escape the parameter. Rails makes this easy:
user_login = "admin" # or, for example, params['user']
Avatar.find(:all, :include => :user,
:conditions => ["users.login = ?", user_login])