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Conditions and combinations

Conditions make a form react to answers.

They let you say:

If this is true, ask that next.

When to use them​

  • Show follow-up questions only when they matter.
  • Require extra fields when a previous answer is yes.
  • Keep the form shorter for doctors.

The simplest mental model​

if / then / else​

"medications": {
  "title": "Medications",
  "type": "object",
  "properties": {
    "takes-medications": {
      "title": "Patient currently takes medications",
      "type": "boolean",
      "description": "Confirm if the patient is actively taking any medication"
    }
  },
  "allOf": [
    {
      "if": {
        "properties": { "takes-medications": { "const": true } },
        "required": ["takes-medications"]
      },
      "then": {
        "properties": {
          "medication-list": {
            "title": "List medications",
            "type": "array",
            "items": {
              "title": "Medication",
              "type": "string",
              "description": "Name and dose"
            },
            "minItems": 1
          }
        },
        "required": ["medication-list"]
      },
      "else": {
        "properties": {
          "no-medication-reason": {
            "title": "Reason for no medications",
            "type": "string",
            "description": "Explain why the patient is not taking medications"
          }
        }
      }
    }
  ]
}

This checks takes-medications. If it is true, medication-list is required.

allOf: stack rules​

allOf means every rule must pass.

"blood-pressure": {
  "title": "Blood pressure (mmHg)",
  "type": "string",
  "description": "Systolic/diastolic like 120/80",
  "allOf": [
    { "pattern": "^\d{2,3}/\d{2,3}$" },
    { "maxLength": 7 }
  ]
}

Both rules must pass.

oneOf: choose exactly one shape​

oneOf means exactly one option should match.

"follow-up": {
  "title": "Follow-up plan",
  "type": "object",
  "oneOf": [
    {
      "title": "Clinic visit",
      "properties": {
        "visit-date": { "title": "Visit date", "type": "string", "format": "date" }
      },
      "required": ["visit-date"]
    },
    {
      "title": "Virtual check-in",
      "properties": {
        "contact-method": {
          "title": "Contact method",
          "type": "string",
          "oneOf": [
            { "const": "PHONE", "title": "Phone" },
            { "const": "VIDEO", "title": "Video" }
          ]
        }
      },
      "required": ["contact-method"]
    }
  ]
}

Use it when the doctor must choose one path.

anyOf: allow one or more shapes​

anyOf means one or more rules can match.

"pain-documentation": {
  "title": "Pain documentation",
  "type": "string",
  "description": "Record either a numeric score or a narrative",
  "anyOf": [
    { "pattern": "^[0-9]|10$" },
    { "minLength": 15 }
  ]
}

Use it when several answer shapes are acceptable.

Simple rule​

Start simple. Too many conditions make forms hard to maintain. Use conditions only when they make the doctor's job easier.