Feature: on the fly HMIS version mapping

#General Description For the purposes of longitudinal reporting and normalizing data for upload or real-time use into other systems, it is often necessary to convert data to a previous or later version of the HMIS Data Standard. For example, someone may need to have a 2015 data standard's client gender data "upconverted" to the equivalent 2016 version of gender (which has different gender categories). HUD publishes the year-to-year version mapping for us to use in this conversion. Since HMISLynk stores data in its original version specific format, to maintain exact fidelity to the originally collected data, on-demand conversion of any data element stored for a homeless client migration should be provided, both in the APIs and in the bulk download formats. This also has the side effect of turning HMISLynk into a conversion utility, which is always in great demand in the HMIS practitioner field.

#Implementation An API flag (perhaps a url query parameter) for "map-to-year" with a version specific year value. So: GET .../v2015/clients/{client_id}"?map-to-rear=2014" requested from the v2015 APIs would "downconvert" that particular element to v2014 in the response.

Additional thoughts:

• Daisy-chaining conversions. Since versions are typically convertible up or down one major year version, the process would convert (under the hood) in two steps to go from v2014 -> v2016
• There would be a standard error code in an unconvertible situation, say, where the data element no longer exists in the target version.