ActiveRecord save problem

rubyonrails-talk
1

Hey I have a problem with saving data to my sqlite db using active record.

when i query an object from the db, update a property and save it using the active record save command it returns true, but nothing happens in the database. the user_course object is the right object from the db, it just doesn't update the data property.

# get user user = User.find_by_id(req.query["user_id"]); #get user-course data user_course = user.user_courses.find_by_course_id(req.query["course_id"]) # set new data user_course.data= "test" # save user_course.save

thx

2

Is their an error appearing in the log?

3

Hey I have a problem with saving data to my sqlite db using active record.

when i query an object from the db, update a property and save it
using the active record save command it returns true, but nothing happens in the database. the user_course object is the right object from the db, it just
doesn't update the data property.

# get user user = User.find_by_id(req.query["user_id"]); #get user-course data user_course = user.user_courses.find_by_course_id(req.query["course_id"]) # set new data user_course.data= "test" # save user_course.save

call save! instead of save. This should throw an exception indicating
why it couldn't save which should point you at the direction of the
problem

Fred

4

save! also returns true

I think this has something to do with the m:n relation user -> user_courses -> course

when i try to save a attribute of a user object ist works, when i try to save to user_courses ist fails in the described way.

my models look like:

class Course < ActiveRecord::Base

  # set table name: courses   set_table_name 'courses'

  # set primary key: id   set_primary_key 'id'

  # users_courses (1:n)   has_many :user_courses

  # users (m:n -> through table users_courses)   has_many :users, :through => :user_courses

end

class User < ActiveRecord::Base

  set_table_name 'users'   set_primary_key 'id'

  # users_courses (1:n)   has_many :user_courses

  # courses (m:n -> through users_courses)   has_many :courses, :through => :user_courses

end

class UserCourse < ActiveRecord::Base

  # set table name: users_courses   set_table_name 'users_courses'

  # courses (1:n)   belongs_to :course, :foreign_key => 'course_id'

  # users (1:n)   belongs_to :user, :foreign_key => 'user_id'

end

can somebody help?

Frederick Cheung wrote:

5

to start Rails is convention over configuration. change your models to

class Course < ActiveRecord::Base

  # users_courses (1:n)   has_many :user_courses

  # users (m:n -> through table users_courses)   has_many :users, :through => :user_courses

end

class User < ActiveRecord::Base

  # users_courses (1:n)   has_many :user_courses

  # courses (m:n -> through users_courses)   has_many :courses, :through => :user_courses

end

class UserCourse < ActiveRecord::Base

  # set table name: users_courses   set_table_name 'users_courses'

  # courses (1:n)   belongs_to :course, :foreign_key => 'course_id'

  # users (1:n)   belongs_to :user, :foreign_key => 'user_id'

end

6

To start a few questions.

What are the field in the three tables?

Fields are:

users

7

I'm going to go out on a limb and say that you don't have a problem creating a new users_courses record.

I would put money that you need only add a primary key to the users_courses table.

8

Keynan Pratt wrote:

I'm going to go out on a limb and say that you don't have a problem creating a new users_courses record.

I would put money that you need only add a primary key to the users_courses table.

i dont want to have a single primary key, i want a composite one that consists out of user_id and course_id, like it's done in traditional db engieering.

9

Keynan Pratt wrote:

I'm going to go out on a limb and say that you don't have a problem creating a new users_courses record.

I would put money that you need only add a primary key to the users_courses table.

i dont want to have a single primary key, i want a composite one that consists out of user_id and course_id, like it's done in traditional
db engieering.

ActiveRecord doesn't do composite prinmary keys. Just in case, you know that   # set table name: courses   set_table_name 'courses'

  # set primary key: id   set_primary_key 'id' aren't actually needed.

Fred

10

Keynan Pratt wrote:

I would put money that you need only add a primary key to the users_courses table.

Oh, yeah.... you were so right!

But i did achieve what i wanted (a composite primary key) with the composite_primary_keys extension to AR. Sheems to work fine.

Thanks for pointing me in the right direction!

ck