HL7 v2 Input

FUME converts HL7 v2 ER7 messages to JSON before evaluation. The normalized JSON is keyed by segment id and uses dictionary-backed field names instead of raw field numbers.

Inspect normalized JSON

Use the root endpoint with fume: "$" to inspect the parsed message before you write mappings against it.

If you need the canonical endpoint guidance for POST /, saved mappings, or verbose execution, see Server API execution patterns.

{
  "input": "MSH|^~\\&|...",
  "contentType": "x-application/hl7-v2+er7",
  "fume": "$"
}

For HL7 v2 requests, input is the original message string.

Original input file

Canonical HL7 v2 input

This compact ADT message is parsed to JSON before evaluation.

HL7 v2

MSH|^~\&|EXCARE|EXCARE-CLINIC|FUME|FUME|20260318091500||ADT^A01|msg-0001|P|2.5
EVN|A01|20260318091500
PID|1||rec-5001^^^EXCARE^MR||Reed^Avery||19900612|F
PV1|1|O|||||||||||||||||enc-1001^^^EXCARE^VN

Normalized JSON before evaluation

Normalized JSON

This is the parsed HL7 v2 structure that the mapping engine evaluates.

{
  "MSH": {
    "SegmentDescription": "Message Header",
    "MessageLine": 1,
    "FieldSeparator": "|",
    "EncodingCharacters": "^~\\&",
    "SendingApplication": {
      "NamespaceID": "EXCARE"
    },
    "SendingFacility": {
      "NamespaceID": "EXCARE-CLINIC"
    },
    "ReceivingApplication": {
      "NamespaceID": "FUME"
    },
    "ReceivingFacility": {
      "NamespaceID": "FUME"
    },
    "DateTimeOfMessage": {
      "Time": "2026-03-18T09:15:00"
    },
    "MessageType": {
      "MessageCode": "ADT",
      "TriggerEvent": "A01"
    },
    "MessageControlID": "msg-0001",
    "ProcessingID": {
      "ProcessingID": "P"
    },
    "VersionID": {
      "VersionID": "2.5"
    }
  },
  "EVN": {
    "SegmentDescription": "Event Type",
    "MessageLine": 2,
    "EventTypeCode": "A01",
    "RecordedDateTime": {
      "Time": "2026-03-18T09:15:00"
    }
  },
  "PID": {
    "SegmentDescription": "Patient Identification",
    "MessageLine": 3,
    "SetID": "1",
    "PatientIdentifierList": {
      "IDNumber": "rec-5001",
      "AssigningAuthority": {
        "NamespaceID": "EXCARE"
      },
      "IdentifierTypeCode": "MR"
    },
    "PatientName": {
      "FamilyName": {
        "Surname": "Reed"
      },
      "GivenName": "Avery"
    },
    "DateTimeOfBirth": {
      "Time": "1990-06-12"
    },
    "AdministrativeSex": "F"
  },
  "PV1": {
    "SegmentDescription": "Patient Visit",
    "MessageLine": 4,
    "SetID": "1",
    "PatientClass": "O",
    "VisitNumber": {
      "IDNumber": "enc-1001",
      "AssigningAuthority": {
        "NamespaceID": "EXCARE"
      },
      "IdentifierTypeCode": "VN"
    }
  }
}

Parse embedded HL7 v2 mid-mapping

If part of your input still contains a raw HL7 v2 message string, use $v2json() to parse that message into the same normalized JSON shape during evaluation.

What to expect

• Segment ids such as MSH, EVN, PID, and PV1 become top-level JSON keys.
• Field and component names come from the HL7 dictionary-backed parser.
• Date and time fields are normalized into JSON string values with a more usable timestamp shape where the datatype supports it.
• Message shape depends on which segments and fields are present, so inspect the normalized JSON with fume: "$" before you write or debug a mapping.

A mapping that works against this normalized JSON also works when you send the original HL7 v2 message, because parsing happens before evaluation.