apple/pkl · error · MissingFieldException

value

Error message

value

What it means

MissingFieldException(jsObj, "value") is thrown by DependencyMetadata.parsePObject when a DataSize-typed annotation/metadata value lacks the required `value` field. A DataSize value must supply both a `unit` symbol and a numeric `value`; the missing field makes the size unrepresentable. It indicates an incomplete nested value object in the metadata.

Source

Thrown at pkl-core/src/main/java/org/pkl/core/packages/DependencyMetadata.java:246

          var className = classInfoObj.getString("class");
          var moduleUri = classInfoObj.getString("moduleUri");
          var props = jsObj.getObject("properties");
          var classInfo = PClassInfo.get(moduleName, className, new URI(moduleUri));
          var properties = new HashMap<String, Object>();
          for (var kv : props.entrySet()) {
            properties.put(kv.getKey(), parsePObject(kv.getValue()));
          }
          return new PObject(classInfo, properties);
        }
        case "Pattern" -> {
          var value = jsObj.getString("value");
          return Pattern.compile(value);
        }
        case "DataSize" -> {
          var symbol = jsObj.getString("unit");
          var value = jsObj.get("value");
          if (value == null) {
            throw new MissingFieldException(jsObj, "value");
          }
          var unit = DataSizeUnit.parse(symbol);
          if (unit == null) {
            throw new PklException("Invalid DataSize unit symbol: " + symbol);
          }
          if (!(value instanceof Double num)) {
            throw new FormatException("double", value.getClass());
          }
          return new DataSize(num, unit);
        }
        case "Duration" -> {
          var symbol = jsObj.getString("unit");
          var value = jsObj.get("value");
          if (value == null) {
            throw new MissingFieldException(jsObj, "value");
          }
          var unit = DurationUnit.parse(symbol);
          if (unit == null) {

View on GitHub (pinned to f3efcbfc9b)

Solutions

1. Add the numeric `value` field alongside `unit`, e.g. {"type": "DataSize", "unit": "mb", "value": 10.0}.
2. Regenerate the metadata with `pkl project package`.
3. Validate the metadata JSON against the expected nested-value shape before publishing.
4. Check for truncated writes if the field was expected to be present.

Example fix

// before
{"type": "DataSize", "unit": "gb"}
// after
{"type": "DataSize", "unit": "gb", "value": 2.0}

var entry = root.get("...");
if (entry.get("type").asString().equals("DataSize")) {
  if (!entry.has("value") || !entry.get("value").isNumber())
    throw new IllegalStateException("DataSize entry requires numeric 'value' and 'unit'");
}

When it happens

Trigger: Parsing metadata whose entry of type "DataSize" contains {"unit": "mb"} with no "value" key.

Common situations: Hand-writing annotation values and omitting the numeric component; custom generators emitting only the unit; partially truncated metadata objects.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• Invalid DataSize unit symbol:
• double
• object
• array
• Could not read annotation. Invalid object:

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/0b01e0b87eef81ee. Report an issue: GitHub.