Check if record exists from controller in Rails -


in app user can create business. when trigger index action in businessescontroller want check if business related current_user.id:

  • if yes: display business.
  • if no: redirect new action.

i trying use this:

if business.where(:user_id => current_user.id) == nil   # no business found end

but returns true when business doesn't exist...

how can test if record exists in database?

why code not work?

the where method returns activerecord::relation object (acts array contains results of where), it can empty never nil.

business.where(id: -1)   #=> returns empty activerecord::relation ( similar array ) business.where(id: -1).nil? # ( similar == nil? )  #=> returns false business.where(id: -1).empty? # test if array empty ( similar .blank? )  #=> returns true

how test if record exists?

option 1: using .exists?

if business.exists?(user_id: current_user.id)   # same business.where(user_id: current_user.id).exists?   # ... else   # ... end

option 2: using .present? (or .blank?, opposite of .present?)

if business.where(:user_id => current_user.id).present?   # less efficiant using .exists? (see generated sql .exists? vs .present?) else   # ... end

option 3: variable assignment in if statement

if business = business.where(:user_id => current_user.id).first   business.do_some_stuff else   # else end

option 3b: variable assignment

business = business.where(user_id: current_user.id).first if business   # ... else   # ... end

you can use .find_by_user_id(current_user.id) instead of .where(...).first

best option:

  • if don't use business object(s): option 1
  • if need use business object(s): option 3

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