Replicate does not seem to work with Rails 4.2.3 and Ruby 2.2.2

[ankuriitk]

Hi, Replicate gem looks awesome and seems the right thing for selectively copying data from prod to my devel db. However, either I am not following the steps correctly or replicate does not work with Rails 4.2.3. In either case, will appreciate your help. Here is what I did:

1. Added gem 'replicate' to my Gemfile
2. Added a config/replicate/dump.rb file that requires 'config/environment' and added simple code to dump Company.find(16)
3. Ran the following command on my production DB machine:
   RAILS_ENV=prod replicate -r ./config/environment -d config/replicate/dump.rb > dumped_data

When I do this, I get the following error:
/var/www/fbdash/releases/20151124123929/config/application.rb:47:in <class:Application>': undefined method[]' for nil:NilClass (NoMethodError)
from /var/www/fbdash/releases/20151124123929/config/application.rb:17:in <module:AdIQ>' from /var/www/fbdash/releases/20151124123929/config/application.rb:16:in<top (required)>'
from /var/www/fbdash/releases/20151124123929/config/environment.rb:2:in `require'

My application.rb snippet looks like this:
...
LIne 46: redis_config = YAML.load_file(Rails.root + 'config/redis.yml')[Rails.env]
Line 47: url_prefix = redis_config['url_prefix']
db = redis_config['cache_db']

I am not sure why it is not picking redis_config as the prod app works just fine.

[ankuriitk]

Any update on this? @rtomayko can you please help ?

[rtomayko]

Hmm, yeah it looks like redis_config is nil. Maybe try RAILS_ENV=production instead of "prod"? This smells like a general environment loading issue.

[ankuriitk]

Thanks @rtomayko for the quick response. My bad for the typo. After giving RAILS_ENV=production, I get the following error. Do I need to explicitly give dump_replicants for each AR class? I thought replicate gem handles that automatically?

/var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/dumper.rb:85:in block in dump': Company must respond to #dump_replicant (NoMethodError) from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/dumper.rb:78:ineach'
from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/dumper.rb:78:in dump' from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/dumper.rb:60:inblock in load_script'
from config/replicate/dump.rb:4:in load_script' from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/dumper.rb:61:ininstance_eval'
from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/dumper.rb:61:in load_script' from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/bin/replicate:77:inblock in <top (required)>'
from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/dumper.rb:28:in block in initialize' from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/emitter.rb:9:ininitialize'
from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/lib/replicate/dumper.rb:26:in initialize' from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/bin/replicate:70:innew'
from /var/www/fbdash/shared/bundle/ruby/2.2.0/gems/replicate-1.5.1/bin/replicate:70:in <top (required)>' from /home/deploy/.rvm/gems/ruby-2.2.2/bin/replicate:23:inload'
from /home/deploy/.rvm/gems/ruby-2.2.2/bin/replicate:23:in <main>' from /home/deploy/.rvm/gems/ruby-2.2.2/bin/ruby_executable_hooks:15:ineval'
from /home/deploy/.rvm/gems/ruby-2.2.2/bin/ruby_executable_hooks:15:in `

'

[u007]

it requires to declare this method on all models,
so ive added to my base model

def dump_replicant(dumper, opts={})
    fields = attribute_names
    dumper.write self.class, id, fields, self
end

but for some reason, the data being exported and imported without values.
ive many rows without values in most of the fields