stanfordnlp/CoreNLP · error · RuntimeException

Cannot get field from

Error message

Cannot get field ${fieldName} from ${v}

What it means

Thrown when the FIELD value function cannot read the requested field from an object via reflection; the underlying NoSuchFieldException or IllegalAccessException is wrapped in a RuntimeException. It means the field name in the expression does not exist on (or is not accessible from) the target object's class.

Solutions

1. Verify the field name against the target class (or add the field).
2. Make the field public, or access it via a public getter through a supported function instead of FIELD.
3. Catch RuntimeException around expression evaluation and fall back to a null/typed value.

Example fix

// before
Value v = FIELD($obj, "sentance");  // misspelled
// after
Value v = FIELD($obj, "sentence");

try { Class.forName(obj.getClass().getName(), false, cl).getField(fieldName); } catch (NoSuchFieldException e) { /* invalid field name */ }

boolean hasField(Object o, String name) { try { o.getClass().getField(name); return true; } catch (NoSuchFieldException e) { return false; } }

try { Value v = FIELD($obj, fieldName); } catch (RuntimeException e) { if (e.getMessage() != null && e.getMessage().startsWith("Cannot get field ")) { v = Expressions.createValue(null, null); } else throw e; }

When it happens

Trigger: Evaluating a TokensRegex expression using FIELD(obj, "fieldName") where fieldName is misspelled or absent from the object's class, or the field is inaccessible (not public, wrong classloader).

Common situations: Typo'd field names in TokensRegex custom expressions; referencing fields of private classes or after refactoring renamed fields; accessing fields of wrapper/boxed objects mistakenly assumed to be the domain object.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Error getting field value for
• Invalid annotation key
• Unknown rule type:
• Error creating composite rule: no annotation field
• Annotation field cannot be null

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/68cbf5a2c38e2300. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/ling/tokensregex/types/ValueFunctions.java:1345

                    if (elem instanceof Value) {
                      list2.add(((Value) elem).get());
                    } else {
                      list2.add(elem);
                    }
                  }
                  f.set(obj, list2);
                }
              } else {
                f.set(obj, Arrays.asList(fieldValue.get()));
              }
            } else {
              f.set(obj, fieldValue.get());
            }
          }
        }
        return Expressions.createValue(null, f.get(obj));
      } catch (NoSuchFieldException | IllegalAccessException ex) {
        throw new RuntimeException("Cannot get field " + fieldName + " from " + v, ex);
      }
    }
  };

  public static final ValueFunction LIST_VALUE_FUNCTION = new NamedValueFunction("LIST_VALUE") {
    @Override
    public String getParamDesc() {
      return "List list,int index,[Object value]";
    }

    // First argument is List
    // Second argument is index of element to select
    // Third argument (optional) is value to assign list element
    @Override
    public boolean checkArgs(List<Value> in) {
      if (in.size() != 2 && in.size() != 3) {
        return false;
      }

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