CODEWITHSUNDEEP
ruby-on-railsrubyscopeexists
surgentt
surgentt

Reputation: 406

Rails Scoping for Existence

I am running Rails 4.0. Ruby 2.0

For signing up, I only ask users to provide me with there email in the new page.

In the update action, I then ask users for their name.

When listing users in the Index action, I only want to show users have updated their name.

I know I need to scope based on if users have updated their name.

User Model

scope :name, where(name: true)

User Controller

def index
  @users = User.name
end

Error

undefined method `gsub' for #

I Think the issue is the way, I am calling the scope. I might need to use exists?

Any help is greatly, appreciated. Thank you.

Upvotes: 1

Views: 77

Answers (2)

maček
maček

Reputation: 77786

Personally, just to be a little more conventional, I would use

class User < ActiveRecord::Base
  scope :has_name, where("users.name != ''")
end

This way, when your model gets joined with another, you won't introduce a column ambiguity in the event multiple tables have a name column

Consider this example

$ rails new app
$ cd app
$ rails g resource User name:string company_id:integer
$ rails g resource Company name:string
$ rake db:migrate

Our models

class User < ActiveRecord::Base
  belongs_to :company
  scope :has_name, where("name != ''")
end

class Company < ActiveRecord::Base
  has_many :users
end

A problem

$ rails c
irb> User.has_name.join(:company)

Oh noes!

User Load (0.4ms)  SELECT "users".* FROM "users" INNER JOIN 
  "companies" ON "companies"."id" = "users"."company_id" WHERE 
  (name != '')

SQLite3::SQLException: ambiguous column name: name: SELECT
  "users".* FROM "users" INNER JOIN "companies" ON 
  "companies"."id" = "users"."company_id" WHERE (name != '')

ActiveRecord::StatementInvalid: SQLite3::SQLException: ambiguous 
  column name: name: SELECT "users".* FROM "users" INNER JOIN 
  "companies" ON "companies"."id" = "users"."company_id" WHERE 
  (name != '')

Let's fix the scope

class User < ActiveRecord::Base
  belongs_to :company
  scope :has_name, where("users.name != ''")
end

Re-run our query

irb> reload!
irb> User.has_name.join(:company)

Proper output

User Load (0.1ms)  SELECT "users".* FROM "users" INNER JOIN "companies" 
  ON "companies"."id" = "users"."company_id" WHERE (users.name != '')

=> []

Upvotes: 3

nbrew
nbrew

Reputation: 781

You could use:

scope :with_name, where("name <> ''")

Though the above doesn't tell you if they've actually modified their name, just that it isn't blank. If you wanted to track the name column for changes, you could use something like the PaperTrail gem for this.

Based on additional feedback, I'd recommend:

scope :with_name, where("users.name != ''")

Upvotes: 1

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