Written Tutorial

Problem

You want to find all JSON documents that are missing a particular property.

Solution

Applies to MarkLogic versions 8+

cts.search(
  cts.notQuery(
    cts.jsonPropertyScopeQuery(
      "target", 
      cts.trueQuery()
    )
  )
)

cts:search(
  fn:doc(),
  cts:not-query(
    cts:json-property-scope-query(
      "targetElement",
      cts:true-query()
    )
  )
)

Discussion

MarkLogic’s built-in search engine uses query criteria to identify matching fragments. The indexes map terms (words, phrases, structures, etc.) to fragment identifiers. To run a search, the specified terms are looked up in the appropriate index to find fragment identifiers. In the case of cts:not-query, the search will return any fragment identifiers except those matched by the nested query.

cts:json-property-scope-query is a useful way to constrain a search to part of a document. The function restricts the nested query to matching within the specified JSON property.

The cts:true-query query passed to cts:json-property-scope-query does what it sounds like — it matches everything. Passed to cts:json-property-scope-query, this provides a simple way to test for the existence of an element.1