What causes "Error getting nested result map values for '{}'. Cause: {}" in mybatis/mybatis-3?

Read the cause SQLException and fix what it points at (unknown column, cannot cast value, etc.).

mybatis/mybatis-3 · error · ExecutorException

Error getting nested result map values for

Error message

Error getting nested result map values for '{}'.  Cause: {}

What it means

A JDBC SQLException escaped while MyBatis read rows for a nested resultMap (an association or collection joined into the parent result). It is wrapped in an ExecutorException naming the property whose nested mapping failed, with the SQLException attached as cause. The mapping structure reached the JDBC layer; the driver then failed reading a value, so the real reason is in the cause.

Solutions

Read the cause SQLException and fix what it points at (unknown column, cannot cast value, etc.).
Check the nested resultMap's <result column="..."> names against the SELECT's actual (aliased) columns.
Register or specify a TypeHandler for the nested property's Java/JDBC type combination.
Reproduce the SELECT manually in a SQL client with the same aliases to confirm column names and types.

Defensive patterns

Strategy: try-catch

Try / catch

try {
  return session.selectList("selectAuthorWithPosts");
} catch (PersistenceException e) {
  if (e.getMessage() != null && e.getMessage().contains("nested result map values")) {
    Throwable cause = e.getCause(); // SQLException with real driver reason
    log.error("Nested mapping for property failed: {}", cause == null ? "?" : cause.getMessage());
  }
  throw e;
}

Prevention

Test nested resultMaps against the real schema in CI (column alias drift is the top cause).
Register explicit TypeHandlers for exotic column types used in nested maps.
Log the full cause chain in a central PersistenceException handler so driver details are never lost.

When it happens

Trigger: A resultMap with a nested <association>/<collection> resultMap; during getRowValue for the nested map a typeHandler.getResult(...) call throws SQLException — wrong column name, incompatible JDBC type conversion, exhausted stream, or driver-specific read error.

Common situations: Column alias typos in JOIN selects; missing typeHandler for an exotic column type inside a nested map; DB enum/json columns read with the wrong handler; driver cursor/streaming constraints on large nested result sets.

Related errors

AI-assisted analysis of mybatis/mybatis-3@008069adb1 (2026-08-14). Data as JSON: /api/errors/b5c123ec1c146830. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/org/apache/ibatis/executor/resultset/DefaultResultSetHandler.java:1434

                linkObjects(metaObject, resultMapping, ancestorObject); // issue #385
              }
              continue;
            }
          }
          final CacheKey rowKey = createRowKey(nestedResultMap, rsw, columnPrefix);
          final CacheKey combinedKey = combineKeys(rowKey, parentRowKey);
          Object rowValue = nestedResultObjects.get(combinedKey);
          boolean knownValue = rowValue != null;
          instantiateCollectionPropertyIfAppropriate(resultMapping, metaObject); // mandatory
          if (anyNotNullColumnHasValue(resultMapping, columnPrefix, rsw)) {
            rowValue = getRowValue(rsw, nestedResultMap, combinedKey, columnPrefix, rowValue);
            if (rowValue != null && !knownValue) {
              linkObjects(metaObject, resultMapping, rowValue);
              foundValues = true;
            }
          }
        } catch (SQLException e) {
          throw new ExecutorException(
              "Error getting nested result map values for '" + resultMapping.getProperty() + "'.  Cause: " + e, e);
        }
      }
    }

    // (issue #101)
    if (resultMap.hasResultMapsUsingConstructorCollection()) {
      foundValues = applyNestedPendingConstructorCreations(rsw, resultMap, metaObject, parentPrefix, parentRowKey,
          newObject, foundValues);
    }

    return foundValues;
  }

  private String getColumnPrefix(String parentPrefix, ResultMapping resultMapping) {
    final StringBuilder columnPrefixBuilder = new StringBuilder();
    if (parentPrefix != null) {
      columnPrefixBuilder.append(parentPrefix);

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