Why is this object undefined? Ruby, Rails, Gmail error - ruby-on-rails

Question

I can't seem to figure out why I am getting the error :
2017-01-03T02:57:35.239505+00:00 app[web.1]: I, [2017-01-03T02:57:35.239437 #4] INFO -- : [89b504ee-5835-4bfa-a3ff-91a3a84549f6] Parameters: {"id"=>"3"}
2017-01-03T02:57:35.243975+00:00 app[web.1]: D, [2017-01-03T02:57:35.243890 #4] DEBUG -- : [89b504ee-5835-4bfa-a3ff-91a3a84549f6] User Load (1.5ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 ORDER BY "users"."id" ASC LIMIT $2 [["id", 22], ["LIMIT", 1]]
2017-01-03T02:57:35.468562+00:00 app[web.1]: true
2017-01-03T02:57:35.476648+00:00 app[web.1]: D, [2017-01-03T02:57:35.476563 #4] DEBUG -- : [89b504ee-5835-4bfa-a3ff-91a3a84549f6] Blueprint Load (2.7ms) SELECT "blueprints".* FROM "blueprints" WHERE "blueprints"."id" = $1 LIMIT $2 [["id", 3], ["LIMIT", 1]]
2017-01-03T02:57:35.477654+00:00 app[web.1]: I, [2017-01-03T02:57:35.477582 #4] INFO -- : [89b504ee-5835-4bfa-a3ff-91a3a84549f6] Completed 500 Internal Server Error in 238ms (ActiveRecord: 5.5ms)
2017-01-03T02:57:35.478257+00:00 app[web.1]: F, [2017-01-03T02:57:35.478177 #4] FATAL -- : [89b504ee-5835-4bfa-a3ff-91a3a84549f6]
2017-01-03T02:57:35.478313+00:00 app[web.1]: F, [2017-01-03T02:57:35.478256 #4] FATAL -- : [89b504ee-5835-4bfa-a3ff-91a3a84549f6] Gmail::Client::DeliveryError (Couldn't deliver email: undefined method `subject' for nil:NilClass):
For some reason the object #current_blueprint doesn't seem to be working inside of the gmail.deliver block. Am I missing something obvious?
Appreciate any help. Thanks!
#current_blueprint = Blueprint.find(params[:id])
mail_status = gmail.deliver! do
to "email#gmail.com"
subject #current_blueprint.subject
html_part do
content_type 'text/html; charset=UTF-8'
body #current_blueprint.body
end
end
puts mail_status

Answer 1

Try just current_blueprint without the # sign.
Sometime a library executes a do end with a different self and can thus not access instance variables, but it should be able to access local variables that are in scope.
Just guessing, let me know whether it works.