Validation failed on rake db:seed - ruby-on-rails

Question

I'm doing chapter 12 of hartle's tutorial. When I ran bundle exec rake db:seed I got this error:
ActiveRecord::RecordInvalid: Validation failed: Email has already been taken
I try running
rake db:reset
rake db:migrate
rake db:test:prepare
And at last
rake db:populate
but they didn't solve the problem. When I run rake db:populate it gives:
Don't know how to build task 'db:populate'
This is my seeds.rb file:
# Users
User.create!(name: "Example User",
email: "example#railstutorial.org",
password: "foobar",
password_confirmation: "foobar",
admin: true,
activated: true,
activated_at: Time.zone.now)
99.times do |n|
name = Faker::Name.name
email = "example-#{n+1}#railstutorial.org"
password = "password"
User.create!(name: name,
email: email,
password: password,
password_confirmation: password,
activated: true,
activated_at: Time.zone.now)
end
# Microposts
users = User.order(:created_at).take(6)
50.times do
content = Faker::Lorem.sentence(5)
users.each { |user| user.microposts.create!(content: content) }
end
# Following relationships
users = User.all
user = users.first
following = users[2..50]
followers = users[3..40]
following.each { |followed| user.follow(followed) }
followers.each { |follower| follower.follow(user) }
I guess maybe the problem is with this line email = "example-#{n+1}#railstutorial.org"

Answer 1

Your problem is that rake db:reset not only drops and recreates the database, but it also migrates and seeds it as well. So essentially what's happening is this:
rake db:drop
rake db:create
rake db:schema:load # (think of this as running all the migrations you've run before)
rake db:seed # (creates your 100 database users)
and then you run:
rake db:migrate # (likely unnecessary, but it causes no harm)
rake db:test:prepare # (prepares the test database)
rake db:prepare # (runs the seeds AGAIN and causes your errors)
Obviously, from this if you just stop running the rake db:prepare command your problem will go away. However, to avoid these things in the future, I strongly recommend putting a little bit of logic in your seed file. It's just Ruby, so you could wrap the User creates in an unless statement, such as:
unless User.find_by( email: "example#railstutorial.org" )
# create all 100 users
end
This will prove to be especially valuable if you have a site on production that still uses seed data (such as a SiteSetting table); you need to make sure the data makes its way into your production database, but you'll create duplicate records (or errors) running the seed again without dropping.
As an additional reference for the answer to your question, see the selected answer to this one.
I hope this provides all the information you need!

Answer 2

I'm doing chapter 12 of hartle's tutorial. When I ran bundle exec rake
db:seed I got this error:
ActiveRecord::RecordInvalid: Validation failed: Email has already been
taken
When you run rake db:reset, it will seed the database for you. When you then run rake db:seed, an exception will be thrown, because you are using create! in your seeds.rb file. Unlike create, create! raises an exception when the validations fail.
You can check this by running rake db:reset, and then using rails console to check your database entries.
There are a couple things you could do to prevent this, but why would you, when your data is already there?
When I run rake db:populate it gives:
Don't know how to build task 'db:populate'
Unless you define it yourself, there is no rake task named db:populate.

Answer 3

try using:
if the case is already existing email it will solve it.
email = "example-#{rand(100000)}#railstutorial.org"
and you can also see errors:
user = User.new(name: "Example User",
email: "example#railstutorial.org",
password: "foobar",
password_confirmation: "foobar",
admin: true,
activated: true,
activated_at: Time.zone.now)
user.errors
user.save if user.valid

Answer 4

Do you have both faker and populator installed in your Gemfile? That is most likely apart of the issue. Make sure you have run:
gem install populator #From the command line
and include it in your Gemfile:
gem 'populator'
Here is a link to the Git repo https://github.com/ryanb/populator/tree/master
Great article here also: http://sudharti.github.io/articles/using-faker-and-populator-rails/