xai-org/x-algorithm · error · SemanticCheckFailure

field %s not found in the metadata of thrift class %s

Error message

field %s not found in the metadata of thrift class %s

What it means

ThriftType.getFieldType resolves a field against the class's apache-thrift FieldMetaData map. A null lookup means the TBase class has no such thrift field, and SemanticCheckFailure is thrown.

Source

Thrown at botmaker/src/java/com/twitter/botmaker/compiler/types/ThriftType.java:166

        throw new SemanticCheckFailure(
            String.format("Unsupported field type %s", valueMetaData.type));
    }
  }

  @Override
  public Set<String> getFieldNames() {
    return metadataMap.keySet();
  }

  public FieldMetaData getFieldMetadata(String fieldName) {
    return metadataMap.get(fieldName);
  }

  @Override
  public Type getFieldType(String fieldName) throws SemanticCheckFailure {
    FieldMetaData metaData = metadataMap.get(fieldName);
    if (metaData == null) {
      throw new SemanticCheckFailure(
          String.format("field %s not found in the metadata of thrift class %s",
              fieldName, typeBase.getName()));
    }

    FieldValueMetaData valueMetaData = metaData.valueMetaData;
    return valueMetaData.getType();
  }

  @SuppressWarnings("unchecked")
  @Override
  public boolean isSetValue(TBase thriftObj, String fieldName) {
    FieldMetaData metaData = metadataMap.get(fieldName);
    return thriftObj.isSet(thriftObj.fieldForId(metaData.fieldId));
  }

  @SuppressWarnings("unchecked")
  @Override
  public Object getFieldValue(TBase thriftObj, String fieldName) {

View on GitHub (pinned to 24c60942c5)

Solutions

1. Use the exact thrift field name from the generated class's metadataMap (check getFieldNames())
2. Regenerate/redeploy thrift classes matching the rule
3. Remove references to deleted fields

Example fix

// before
thriftType.getFieldType("user_name"); // thrift field is 'username'
// after
thriftType.getFieldType("username");

if (!thriftType.getFieldNames().contains(fieldName)) { /* fail fast */ }

boolean hasField(ThriftType t, String f) { return t.getFieldNames().contains(f); }

catch SemanticCheckFailure; reject rule at load time with unknown field diagnostics

When it happens

Trigger: Calling getFieldType(fieldName) (usually via fieldType(...)) with a name not present in the TBase struct's metadata map — typo, renamed field, or referencing a field from a different struct.

Common situations: Rules written against an older/newer thrift IDL than the generated classes on the classpath; field renamed or removed in the IDL; camelCase vs snake_case confusion in field names.

Related errors

• field %s not found in the metadata of thrift class %s
• Unsupported field type %s
• Unsupported field type %s
• Unsupported field type %s
• Field %s is not defined in thrift type %s

AI-assisted analysis of xai-org/x-algorithm@24c60942c5 (2026-08-28). Data as JSON: /api/errors/a1d63eaedc99a42a. Report an issue: GitHub.