Thursday, November 1, 2018
ruby on rails - undefined method `empty?' for nil:NilClass how to avoid it
Answer
Answer
Hi Together I've got this code:
@coursesFound = @user.available_courses
@courses = []
for course in @coursesFound do
@courseInGroups = course.user_groups
for group in @courseInGroups do
@group = UserGroup.find group.id
if @group.users.map { |u| u.id }.include? @user.id
@courses << course
break
end
end
end
# Wenn ein Kurs keiner Gruppe hinzugefügt wurde
if @courseInGroups.empty?
@courses << course
end
on my debian vm it works fine but on my live system I got this error:
undefined method `empty?' for nil:NilClass
How can I avoid this?
Answer
If this @coursesFound = @user.available_courses returns an empty activerecord relation.
Then this won't execute
for course in @coursesFound do
@courseInGroups = course.user_groups
for group in @courseInGroups do
@group = UserGroup.find group.id
if @group.users.map { |u| u.id }.include? @user.id
@courses << course
break
end
end
end
Which means when you get here @courseInGroups is nil
if @courseInGroups.empty?
@courses << course
end
So your quick fix would be
if @courseInGroups && @courseInGroups.empty?
@courses << course
end
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