CODEWITHSUNDEEP
mysqlruby-on-railsrubyforeign-keysruby-on-rails-5
taynan
taynan

Reputation: 131

Ruby on rails - set up a null foreign key

How do I set a foreign key null? because I want to relate two tables, user and team, but it is not mandatory for a user to have a team.

rails g scaffold Time name: string user: references

Upvotes: 4

Views: 5278

Answers (3)

quyetdc
quyetdc

Reputation: 1585

Rails level ( model validation )

In Rails 4.x , when defining a references, the associated record for belongs_to is optional. From Rails 5.x, this association is required.

In Rails 4, to make associated record required, you will do 

class Photo
  belongs_to :user, required: true
end

In Rails 5, to make associated record optional, you will do

class Photo
  belongs_to :user, optional: true
end

DB level

You need to make sure that your migration does not have constraint null: false. You should check migration to make sure it looks sth like below

create_table :photos do |t|
   t.references :user, null: true, foreign_key: true
end

Upvotes: 5

Yurii
Yurii

Reputation: 691

It's allowed to be null on db level. Within Time models add optional option, like - belongs_to :user, optional: true Check related docs here

Upvotes: 5

Gagan Gupta
Gagan Gupta

Reputation: 1227

When you're designing your tables it's not advisable to put data which is not related to the parent.

For example: User can have multiple photos

user table
id name 

photos table
id url user_id

if you're going to store photos without user_id then those photos will not be retrieved when you want to access photos of a particular user. That's why rails doesn't allow you to store records if you've defined a column as references.

you can refer the issue here DHH github (rails).

In the association add optional: true to achieve this functionality.

Upvotes: 0

Related Questions