Relationship between tables

Rails
1

Hi,

I have a users table(below) and now i want to create a new table
“occupation” so the users can fill in there occupation and store it in
the occupation-table.

Question: how can i realize a realionship between the users-table and
the occupation-table?

class CreateUsers < ActiveRecord::Migration
def self.up
create_table :users do |t|
t.column :username, :string, :limit => 64, :null => false
t.column :email, :string, :limit => 128, :null => false
t.column :hashed_password, :string, :limit => 64
t.column :enabled, :boolean, :default => true, :null => false
t.column :profile, :text
t.column :created_at, :datetime
t.column :updated_at, :datetime
t.column :last_login_at, :datetime
end
add_index :users, :username
end

def self.down
drop_table :users
end
end

Thanks…

Grtz…remco

2

Remco S. wrote:

Hi,

I have a users table(below) and now i want to create a new table
“occupation” so the users can fill in there occupation and store it in
the occupation-table.

Question: how can i realize a realionship between the users-table and
the occupation-table?

class CreateUsers < ActiveRecord::Migration
def self.up
create_table :users do |t|
t.column :username, :string, :limit => 64, :null => false
t.column :email, :string, :limit => 128, :null => false
t.column :hashed_password, :string, :limit => 64
t.column :enabled, :boolean, :default => true, :null => false
t.column :profile, :text
t.column :created_at, :datetime
t.column :updated_at, :datetime
t.column :last_login_at, :datetime
end
add_index :users, :username
end

def self.down
drop_table :users
end
end

Thanks…

Grtz…remco
Hi,
If a user is having many occupations
then you can give like
has_many :occupations in CreateUsers
and
belongs_to :occupation,
:class_name => “UserOccupation”,
:foreign_key => “user_occupation_id”

in Occupation table

3

Abhi M. wrote:

Remco S. wrote:

Hi,

I have a users table(below) and now i want to create a new table
“occupation” so the users can fill in there occupation and store it in
the occupation-table.

Question: how can i realize a realionship between the users-table and
the occupation-table?

class CreateUsers < ActiveRecord::Migration
def self.up
create_table :users do |t|
t.column :username, :string, :limit => 64, :null => false
t.column :email, :string, :limit => 128, :null => false
t.column :hashed_password, :string, :limit => 64
t.column :enabled, :boolean, :default => true, :null => false
t.column :profile, :text
t.column :created_at, :datetime
t.column :updated_at, :datetime
t.column :last_login_at, :datetime
end
add_index :users, :username
end

def self.down
drop_table :users
end
end

Thanks…

Grtz…remco
Hi,
If a user is having many occupations
then you can give like
has_many :occupations in CreateUsers
and
belongs_to :occupation,
:class_name => “UserOccupation”,
:foreign_key => “user_occupation_id”

in Occupation table

Hi,

Thanks for you’re quick reponse…

But must i add a column user_occupation_id in the users-table?

remco

4

On 24 Oct 2007, at 09:49, Remco S. wrote:

in Occupation table

Hi,

Thanks for you’re quick reponse…

But must i add a column user_occupation_id in the users-table?

Possibly. it depends on your data:
if a user has a single occupation then the user table needs an
occupation_id column
if an occupation belongs to a single user then the occupation table
needs a user_id column
if a user can have many occupations and an occupation can have many
users then you don’t need to add columns to either of those table,
but you do need to create a join table occupation_users with columns
user_id and occupation_id.

You then do
class User
has_many :occupation_users
has_many :occupations, :through => :occupation_users
end
and similarly for Occupation.

Fred

5

Remco S. wrote:

Question: how can i realize a realionship between the users-table and
t.column :created_at, :datetime

           :class_name => "UserOccupation",

remco

Actually, if a user has many occupations, then the relationship will
need to be modeled as a has_and_belongs_to_many (HABTM) and you will
need to create a table called user_occupations_users table to model the
many-to-many relationship. Search for has_and_belongs_to_many (HABTM)
and you should be able to get enough to get started.

On the other hand, if a user can belong to only one occupation, then you
need to add a table called occupations and in your user table, you need
to occupation_id as an INT field. You can create a new migration that
adds the column to the table. Then, user belongs_to occupation and
occupation has_many users.

Cheers,
Mohit.
10/24/2007 | 4:58 PM.

6

Hi,
No that depends on your need
I just sent you an example
Thanks

7

well i think
we can do it with a direct has_many relationship between Users and
occupations , no need of an through relationship if users has_many users
only…

But if occupation has many users then we have a many to any
relationship , in this case we will opt for through relationship .
DHH