Sinatra JSON.parse undefined method when moving helper to another file - ruby

Question

I have a route helper that works fine when it's in a "helpers do" block in my route file, but when I move the helper to my helpers.rb file, I get an error. Here is the helper:
def processPutRequest(patient_id, request, _class, foreign_key, route_fragment)
p = Patient.find(patient_id)
data = request.body.read
puts 'request body' + data
data = JSON.parse(data)
host_with_port = request.host_with_port
puts 'hash data: ' + data.inspect
saveListData(params[:id], data, _class, foreign_key)
url = {'url' => "http://#{host_with_port}/patients/#{params[:id]}#{route_fragment}"}.to_json
Rack::Response.new(url)
end
Here is the logging when the helper is in the route file:
request body{"list_data":[{"id":8440,"value":"Removal of ear wax (procedure)"},{"id":9827,"value":"Foreign body in nose (disorder)"}]}
hash data: {"list_data"=>[{"id"=>8440, "value"=>"Removal of ear wax (procedure)"}, {"id"=>9827, "value"=>"Foreign body in nose (disorder)"}]}
And when I move it to the helpers file:
request body{"list_data":[{"id":8440,"value":"Removal of ear wax (procedure)"},{"id":9827,"value":"Foreign body in nose (disorder)"}]}
NoMethodError - undefined method `parse' for Sinatra::JSON:Module:
Am I missing something really simple?
EDIT, got the debugger working. "data" after request.body.read in routes file:
"{"list_data":[{"id":8440,"value":"Removal of ear wax (procedure)"},{"id":9827,"value":"Foreign body in nose (disorder)"}]}"
in helpers file:
"{"list_data":[{"id":8440,"value":"Removal of ear wax (procedure)"},{"id":9827,"value":"Foreign body in nose (disorder)"}]}"
So the content looks identical to me. I can literally cut and paste this method between the two files, it works fine in the routes file, fails with undefined method parse in the helpers file. I'm guessing I've somehow defined that module improperly or have a dandling or missing character, but RubyMine is showing no errors, and the method does at least partially execute, so the method is getting sourced.
Complete helpers file:
module Sinatra
module DynFormat
CONTENT_TYPES={'xml' => 'text/xml','json' => 'application/json'}
def dynamicFormat(data,format=params[:format])
content_type CONTENT_TYPES[format], :charset => 'utf-8'
case format
when 'xml'
data.to_xml
when 'json'
data.to_json
end
end
end
helpers DynFormat
module RouteHelpers
def processPutRequest(patient_id, request, _class, foreign_key, route_fragment)
p = Patient.find(patient_id)
data = request.body.read
puts 'request body' + data
data = JSON.parse(data)
host_with_port = request.host_with_port
puts 'hash data: ' + data.inspect
saveListData(params[:id], data, _class, foreign_key)
url = {'url' => "http://#{host_with_port}/patients/#{params[:id]}#{route_fragment}"}.to_json
Rack::Response.new(url)
end
def saveListData(patient_id, list_data, _class, foreign_key)
p = Patient.find(patient_id)
_class = eval _class
list_data = list_data['list_data']
list_data.each do |x|
_class.create(:patient_id => patient_id, foreign_key => x['id'] )
end
end
end
helpers RouteHelpers
end

Answer 1

When you put your method in the external file, you are putting into a module under the Sinatra namespace:
module Sinatra
module DynFormat
#...
end
module RouteHelpers
def processPutRequest(patient_id, request, _class, foreign_key, route_fragment)
# code that refers to JSON...
end
end
end
When your method calls JSON.parse it ends up finding the Sinatra::JSON module, not the top level JSON module that you intended, and so you get the error undefined method `parse' for Sinatra::JSON:Module.
When you include the method in a helpers block in your main file the method isn’t defined under the Sinatra module, so JSON refers to the correct top level module.
If you need to include Sinatra::JSON, you can explicitly refer to the top level module using :::
data = ::JSON.parse(data)
Also note that you don’t necessarily need to define your helper modules under Sinatra (though the docs do suggest you do). You can move them out of the Sinata module, and then use e.g. Sinatra.helpers RouteHelpers to register them as helpers.

Answer 2

I was requiring both json and sinatra/json. No idea why the last one didn't win all the time, but removing sinatra/json resolved the issue. If something else breaks, I'll spend the time deciding between the two.