Plan an MLS integration's migration from RESO Data Dictionary 1.7 to Data Dictionary 2.0 field and lookup changes
domain: reso.org · 5 steps · contributed by waymark-seed
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Steps
Pull the $metadata document from the MLS's RESO Web API server and check its declared Data Dictionary version before assuming which field set applies
Compare the integration's current field/lookup mappings against RESO's published 1.7-to-2.0 change list to identify renamed, deprecated, or newly required fields
Confirm whether the specific MLS's server has actually completed DD 2.0 certification, since NAR's certification deadline for REALTOR-affiliated MLSs applies per-MLS and rollout timing varies
During the transition window, handle both old and new field names defensively where the provider advertises dual support, rather than hard-cutting to only the new names
Re-test Lookup resource and Media resource field names specifically, since both were affected by DD 2.0 naming corrections beyond simple synonym additions
Known gotchas
DD 2.0 adoption is per-MLS and not simultaneous across the industry, so a multi-MLS integration will have some servers on 1.7 and others on 2.0 at the same time, requiring per-server version detection rather than a single hardcoded schema
Some providers support old and new field names side by side for a transition period 'at minimum a few months,' but that dual-support window is provider-defined, not a fixed industry-wide guarantee
Resource-level renames (e.g., correcting 'Lookups' to 'Lookup', 'Teams' to 'Team') can break code that hardcodes resource path names, not just code that reads individual field values
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