class CreateBallots < ActiveRecord::Migration
def change
create_table :ballots do |t|
t.references :user
t.references :score
t.references :election
t.string :key
t.timestamps
end
add_index :ballots, :user
add_index :ballots, :score
add_index :ballots, :election
end
end
results in:
SQLite3::SQLException: table ballots has no column named user: CREATE INDEX "index_ballots_on_user" ON "ballots" ("user")/home/muhd/awesomevote/db/migrate/20130624024349_create_ballots.rb:10:in `change'
I thought t.references was supposed to handle that for me?
You forgot to add "_id" like this:
add_index :ballots, :user_id
or, if you want it indexed automatically:
t.references :user, index: true
More info: add_index , references
HTH
The answer above is correct, but be aware that:
t.references :user, index: true is only available in Rails 4.0 & up.
In earlier versions of Rails (3.x), index: true will fail silently, leaving you without an index on that table. For Rails 3.2.x & down, use the older syntax:
add_index :ballots, :user_id
Or in full using your example:
class CreateBallots < ActiveRecord::Migration
def change
create_table :ballots do |t|
t.references :user
t.references :score
t.references :election
t.string :key
t.timestamps
end
add_index :ballots, :user_id
add_index :ballots, :score_id
add_index :ballots, :election_id
end
end
Related
I created a scaffold with this command (Rails 5.2.1.1):
rails g scaffold EmailAddress value:string:index
email_address_type:references
email_addressable:references{polymorphic}
position:integer
which resulted in this migration file:
class CreateEmailAddresses < ActiveRecord::Migration[5.2]
def change
create_table :email_addresses do |t|
t.string :value
t.references :email_address_type, foreign_key: true
t.references :email_addressable, polymorphic: true
t.integer :position
t.timestamps
end
add_index :email_addresses, :value
end
end
Unfortunately this raises the following error on rails db:migrate:
Caused by:
ArgumentError: Index name
'index_email_addresses_on_email_addressable_type_and_email_addressa...'
on table 'email_addresses' is too long; the limit is 62 characters
I understand the problem and the error. I'm wondering what the best solution is because the index is not set explicity by add_index but by some background magic.
As Wintermeyer says is one solution, there is another way at least I find smoother to use.
t.references :email_address_type, foreign_key: true,
index: { name: "addressable_index" }
Through this you dont get a bunch of add_index rows in your migration. This helps if you ever have a large migration and need to find a specific index quickly. This is just my personal opinion, Wintermeyer solution is also a working fix!
index: false is the solution for this problem. Followed by an add_index at the bottom. Here is the migration:
class CreateEmailAddresses < ActiveRecord::Migration[5.2]
def change
create_table :email_addresses do |t|
t.string :value
t.references :email_address_type, foreign_key: true
t.references :email_addressable, polymorphic: true, index: false
t.integer :position
t.timestamps
end
add_index :email_addresses, :value
add_index :email_addresses, [:email_addressable_type,
:email_addressable_id],
name: 'email_addressable_index'
end
end
How can I create a relationship table in my migration class that both references are used in an unique index?
class CreateDiagnosticHypotheses < ActiveRecord::Migration
def change
create_table :diagnostic_hypotheses, :id => false do |t|
t.references :accident_indication, index: true
t.references :forms, index: true
t.timestamps null: false
end
add_foreign_key :diagnostic_hypotheses, :accident_indications
add_foreign_key :diagnostic_hypotheses, :forms, column: :diagnostic_hypothesis_id
end
end
When I run rake db:migrate it tries to create separate indexes. How can I create just one unique index with both :accident_indication and :forms references?
You can create unique composite index:
class CreateDiagnosticHypotheses < ActiveRecord::Migration
def change
create_table :diagnostic_hypotheses, :id => false do |t|
t.references :accident_indication
t.references :forms
t.timestamps null: false
end
add_index :diagnostic_hypotheses, [:accident_indication_id, :forms_id], :unique => true
add_foreign_key :diagnostic_hypotheses, :accident_indications
add_foreign_key :diagnostic_hypotheses, :forms, column: :diagnostic_hypothesis_id
end
end
I didn't try it myself, however, but I think you've got the idea.
I have a two separate migration files:
class CreateLeadProfiles < ActiveRecord::Migration
def change
create_table :lead_profiles do |t|
t.belongs_to :Contact
t.timestamps
end
add_index :lead_profiles, :contact_id
end
end
and:
class CreateClientProfiles < ActiveRecord::Migration
def change
create_table :client_profiles do |t|
t.belongs_to :Contact
t.belongs_to :LeadProfile
t.timestamps
end
add_index :client_profiles, :contact_id
add_index :client_profiles, :lead_profile_id
end
end
when running rake db:migrate, I get the following error:
Mysql2::Error: Key column 'lead_profile_id' doesn't exist in table: CREATE INDEX `index_client_profiles_on_lead_profile_id` ON `client_profiles` (`lead_profile_id`)
client_profile belongs_to lead_profile, and so should have a lead_profile_id. And I want that foreign key to be indexed. What am I doing wrong?
Try:
class CreateClientProfiles < ActiveRecord::Migration
def change
create_table :client_profiles do |t|
t.belongs_to :contact
t.belongs_to :lead_profile
t.timestamps
end
add_index :client_profiles, :contact_id
add_index :client_profiles, :lead_profile_id
end
end
Is it necessary to add_index on HABTM join table? I use t.belongs_to (aka t.references). Here is code
class CreateCohortsUsersTable < ActiveRecord::Migration
def change
create_table :cohorts_users, :id => false do |t|
t.belongs_to :cohort
t.belongs_to :user
end
add_index :cohorts_users, :cohort_id # Do I need this?
add_index :cohorts_users, :user_id # Do I need this?
end
end
It's usually a good idea to add a unique index on both columns:
add_index :cohorts_users, [:cohort_id, :user_id], unique: true
I'm trying to use a :has_many :through type association, but I'm getting the following error:
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: work_units.developer_id:
Many other posts about this sort of thing have just had spelling mistakes, but I've checked mine.
class Developer < ActiveRecord::Base
attr_accessible :skype_name, :language_ids, :user_attributes
has_many :work_units
has_many :projects, :through => :work_units
...
end
class Project < ActiveRecord::Base
attr_accessible :complete, :description, :finalised, :price
has_many :work_units
has_many :developers, :through => :work_units
...
end
class WorkUnit < ActiveRecord::Base
attr_accessible :hours_worked
belongs_to :project
belongs_to :developer
end
I've run db:migrate and it didn't complain. I did make a mistake and had to rollback the db then re-migrate, but I think I did it right. I use the annotate gem and it doesn't show any of the relationship ids I'd expect. So, do I need to create a WorkUnits table or am I missing something? The rails guide didn't mention manually making tables.
Edit
Here's the migration I used to create the WorkUnit model and stuff:
class CreateWorkUnits < ActiveRecord::Migration
def change
create_table :work_units do |t|
t.integer :hours_worked, :default => 0
t.timestamps
end
end
end
Edit 2
Snippets from my schema.rb:
create_table "work_units", :force => true do |t|
t.integer "hours_worked", :default => 0
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
create_table "projects", :force => true do |t|
t.string "description"
t.decimal "price", :precision => 8, :scale => 2
t.boolean "complete", :default => false
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
Similarly for :developers. So, why doesn't my migration add the association information for me?
Your WorkUnit migration should look like this:
class CreateWorkUnits < ActiveRecord::Migration
def change
create_table :work_units do |t|
t.integer :hours_worked, :default => 0
t.references :developer
t.references :project
t.timestamps
end
add_index :work_units, :developer_id
add_index :work_units, :project_id
end
end
You need to add the foreign keys to your work_units table.
class CreateWorkUnits < ActiveRecord::Migration
def change
create_table :work_units do |t|
t.integer :hours_worked, :default => 0
t.integer :project_id, null: false
t.integer :developer_id, null: false
t.timestamps
end
add_index :work_units, :project_id
add_index :work_units, :developer_id
end
end
Another way:
class CreateWorkUnits < ActiveRecord::Migration
def change
create_table :work_units do |t|
t.integer :hours_worked, :default => 0
t.belongs_to :project
t.belongs_to :developer
t.timestamps
end
add_index :work_units, :project_id
add_index :work_units, :developer_id
end
end
You can also define these fields when generating your model, then they'll be added to the migration automatically as show in the second snippet.
$ rails g model WorkUnit hours_worked:integer project:belongs_to developer:belongs_to
Hope that helps.
A table for WorkUnit needs to exist, whether that means it migration was automatically generated via scaffolding or if the migration was manually written by you.
If you don't have a migration yet that creates that table, you'll need to create that migration because the table does need to exist.
You do need a work_units table with a project_id and developer_id column.
Have a look at http://xyzpub.com/en/ruby-on-rails/3.2/activerecord_datenbank_anlegen.html if you don't know how to create a table.