NCS Navigator MDES Module

This gem provides a consistent computable interface to the National Children's Study Master Data Element Specification. All of the data it exposes is derived at runtime from the documents provided by the National Children's Study Program Office, which are embedded in the distribution package.

Use

require 'ncs_navigator/mdes'
require 'pp'

mdes = NcsNavigator::Mdes('1.2')
pp mdes.transmission_tables.collect(&:name)

For more details see the API documentation, starting with {NcsNavigator::Mdes::Specification}. (If you're not looking at this document in the API documentation, try looking at rubydoc.info.)

Examine

This gem includes a console for interactively analyzing and randomly poking at the MDES. It is called mdes-console:

$ mdes-console
Documents are expected to be in the default location.
$mdes12 is a Specification for 1.2
$mdes20 is a Specification for 2.0
ruby-1.8.7-p334 :001 >

It is based on ruby's IRB. Use it to examine the loaded MDES data without a lot of edit-save-run cycles:

ruby-1.8.7-p334 :001 > $mdes20.transmission_tables.first.name
 => "study_center"

E.g., find all the variables of a particular XML schema type:

ruby-1.8.7-p334 :002 > $mdes20.transmission_tables.collect { |t| t.variables }.flatten.select { |v| v.type.base_type == :decimal }.collect(&:name)
  => ["correction_factor_temp", "current_temp", "maximum_temp", "minimum_temp", "precision_term_temp", "trh_temp", "salts_moist", "s_33rh_reading", "s_75rh_reading", "s_33rh_reading_calib", "s_75rh_reading_calib", "precision_term_temp", "rf_temp", "correction_factor_temp", "sample_receipt_temp"]

Or the labels for a particular code list:

ruby-1.8.7-p334 :003 > $mdes20.types.find { |t| t.name == 'confirm_type_cl7' }.code_list.collect(&:label)
 => ["Yes", "No", "Refused", "Don't Know", "Legitimate Skip", "Missing in Error"]

Or the number of code lists that include "Yes" as an option:

ruby-1.8.7-p334 :004 > $mdes20.types.select { |t| t.code_list && t.code_list.collect(&:label).include?('Yes') }.size
 => 23

Develop

Writing API docs

Run bundle exec yard server --reload to get a dynamically-refreshing view of the API docs on localhost:8808.