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 must be available on
the system where it is running.

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}.

### 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.