ActiveRecord save problem

Rails
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

On 21 Jan 2008, at 09:40, Christian K. wrote:

update the data property.
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 C. wrote:

On 21 Jan 2008, at 09:40, Christian K. wrote:

update the data property.
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

5

To start a few questions.

What are the field in the three tables?

Fields are:

users

id integer PRIMARY KEY AUTOINCREMENT NOT NULL,
username varchar(20),
pass varchar(20),
pin varchar(20),
firstname varchar(50),
lastname varchar(50),
email varchar(50)

courses

id integer PRIMARY KEY AUTOINCREMENT NOT NULL,
coursecategorie_id integer,
coursetype_id integer NOT NULL,
url varchar(255),
fspath varchar(255),
lastupdate datetime

users_courses

user_id integer NOT NULL,
course_id integer NOT NULL,
coursestatus integer,
suspenddata varchar(50),
score integer,
startdate datetime,
expirationdate datetime,
language varchar(20)

CREATE INDEX users_courses_FKIndex1
ON users_courses
(user_id);

CREATE INDEX users_courses_FKIndex2
ON users_courses
(course_id);

If you find users_courses strait from the db (not through the
association) does it save successfully?

No!

works:

user = User.find_by_id(req.query[“user_id”])
user.pin = “haha”
user.save!

doesn’t work:

only returns one row, because of the limited data in the table
in the debugger everthing sheems ok.

uc = UserCourse.find_by_course_id(req.query[“course_id”])
uc.suspenddata = “haha”
uc.save!

thx ck

6

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.

7

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

======================================================
by convention your join tables should be the pluralized forms of the two
tables in alphabetical order (ie. courses_users) with the model
‘CoursesUsers’

To start a few questions.

What are the field in the three tables?
If you find users_courses strait from the db (not through the
association) does it save successfully?

8

On 21 Jan 2008, at 14:18, Christian K. wrote:

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

9

Keynan P. 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.

10

Keynan P. 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