Full Text Search

Termbox supports text filtering in ValueSet/$expand through the standard filter parameter. The filter is applied to concept displays and designations within the requested value set.

Full text search is intended for UI search boxes and autocomplete workflows. Typo-tolerant fuzzy search is enabled by default and includes prefix matching behavior. You can disable fuzzy search to use prefix-only matching.

Prefix Search

Prefix search treats each search word as a prefix. This makes partial user input work naturally while the user is still typing.

For example, this request can match Left knee fracture even though the final word is incomplete:

GET /ValueSet/$expand?url=http://snomed.info/sct?fhir_vs&filter=left+knee+fra&count=10

A response can include:

{
  "resourceType": "ValueSet",
  "url": "http://snomed.info/sct?fhir_vs",
  "status": "active",
  "expansion": {
    "total": 2,
    "parameter": [
      { "name": "count", "valueInteger": 10 }, 
      { "name": "filter", "valueString": "left knee fra" },
      { "name": "used-codesystem", "valueUri": "http://snomed.info/sct|http://snomed.info/sct/900000000000207008/version/20260701" }
    ],
    "contains": [
      {
        "code": "54331000087107",
        "system": "http://snomed.info/sct",
        "display": "Fracture of left knee"
      },
      {
        "code": "12217721000119105",
        "system": "http://snomed.info/sct",
        "display": "Fracture of bone adjacent to left knee joint prosthesis"
      }
    ]
  }
}

Prefix search is useful for inputs like:

Fuzzy Search

Fuzzy search extends prefix search with typo correction. Termbox automatically fix misspelled query words before running the text search. For example, this request can match a concept containing spinal even though the input contains soinal:

GET /ValueSet/$expand?url=http://snomed.info/sct?fhir_vs&filter=Lumbar+soinal+fusion&count=5

A response can include:

{
  "resourceType": "ValueSet",
  "url": "http://snomed.info/sct?fhir_vs",
  "status": "active",
  "expansion": {
    "parameter": [
      { "name": "count", "valueInteger": 5 },
      { "name": "filter", "valueString": "Lumbar soinal fusion" },
      { "name": "used-codesystem", "valueUri": "http://snomed.info/sct|http://snomed.info/sct/900000000000207008/version/20260701" }
    ],
    "contains": [
      {
        "code": "50172003",
        "system": "http://snomed.info/sct",
        "display": "Lumbar spinal fusion"
      },
      {
        "code": "178643002",
        "system": "http://snomed.info/sct",
        "display": "Spinal fusion: [primary posterior lumbar] or [Bosworth] or [Hibbs]",
        "property": [{ "code": "inactive", "valueBoolean": true }],
        "inactive": true
      },
      {
        "code": "178644008",
        "system": "http://snomed.info/sct",
        "display": "Posterior spinal fusion (& lumbar (& [primary] or [primary NEC] or [named variants])",
        "property": [{ "code": "inactive", "valueBoolean": true }],
        "inactive": true
      },
      {
        "code": "278659001",
        "system": "http://snomed.info/sct",
        "display": "Lumbar spinal fusion for pseudoarthrosis"
      },
      {
        "code": "178642007",
        "system": "http://snomed.info/sct",
        "display": "Fusion spinal joint: [other primary lumbar] or [Moe's posterior]",
        "property": [{ "code": "inactive", "valueBoolean": true }],
        "inactive": true
      }
    ]
  }
}

Fuzzy search is useful for common typo shapes:

Fuzzy search keeps the original search tokens as prefix alternatives. This means valid prefix searches continue to work in the default fuzzy search mode.

Configuration

Fuzzy search is controlled by the FUZZY_SEARCH_ENABLED environment variable. It is enabled by default. Fuzzy queries carry a small performance penalty compared with prefix-only search because Termbox also checks candidate typo corrections before running the text search.

FUZZY_SEARCH_ENABLED=true|false

Set it to false only when you want prefix-only full text search:

See Configuration for the full environment variable reference.