Monday, July 10, 2017

Querying managed metadata using REST (unsupported)

I’m working with a set of SharePoint framework web parts and finally got fed up of using JSOM to work with managed metadata. Referencing JSOM feels wrong for so many reasons in this modern day and age, so I’d rather not do it.

I mean, when the out-of-the-box modern controls in SharePoint can work with terms using REST, why shouldn’t I? I like to believe I’m pretty modern.

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After Fiddling the modern UI I found out that all taxonomy requests are working against a service at /_vti_bin/TaxonomyInternalService.json. This is a good old service, also listed on MSDN at https://msdn.microsoft.com/EN-US/library/microsoft.sharepoint.taxonomy.webservices.taxonomyinternalservice_methods.aspx. It is indeed marked for internal use, and until we get a new public REST point, everything points to that it should indeed work. If not, why would Microsoft use it themselves?

I have put together a sample SPFx web part based on the MSDN documentation, trial and error, showcasing different methods I found useful when retrieving terms. It’s by no means complete, but should help you get started.

You can find the sample at https://github.com/wobba/spfx4fun/tree/master/react-taxonomy-rest (link to all methods)

Samples include:

  • List term stores
  • List term groups in a term store
  • List term sets in a term group
  • Search for term by label
  • Search for term sets by name of term set or term in set
  • Get level one terms of a term set
  • Get child terms for a term

Using these calls you should have enough information to build a metadata driven megamenu, or build a taxonomy picker.

I have included interfaces for all the REST calls with some comments, but not for the returned results. You might have to examine the result JSON and pick out what you need.

And as a nugget I output the JSON with indentation, a tip I picked up from Sahil Malik :)

Sample interface

interface IGetSuggestionsRequest {
  start: string; // query
  lcid: number;
  sspList: string; // guid of term store
  termSetList: string; // guid of term set
  anchorId: string;
  isSpanTermStores: boolean; // search in all termstores
  isSpanTermSets: boolean;
  isIncludeUnavailable: boolean;
  isIncludeDeprecated: boolean;
  isAddTerms: boolean;
  isIncludePathData: boolean;
  excludeKeyword: boolean;
  excludedTermset: string;
}

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