mybatis/mybatis-3 · error · IllegalStateException

There should be the same number of columns and foreignColumn

Error message

There should be the same number of columns and foreignColumns in property {}

What it means

Thrown by ResultMapping.Builder.validate() for joined/multiple result sets (resultSet attribute present). When a mapping declares a resultSet, MyBatis pairs each column with a foreignColumn to correlate rows across result sets, so both lists must have the same length after splitting on commas.

Source

Thrown at src/main/java/org/apache/ibatis/mapping/ResultMapping.java:181

        throw new IllegalStateException(
            "Cannot define both nestedQueryId and nestedResultMapId in property " + resultMapping.property);
      }
      // Issue #4 and GH #39: column is optional only in nested resultMaps but not in the rest
      if (resultMapping.nestedResultMapId == null && resultMapping.column == null
          && resultMapping.composites.isEmpty()) {
        throw new IllegalStateException("Mapping is missing column attribute for property " + resultMapping.property);
      }
      if (resultMapping.getResultSet() != null) {
        int numColumns = 0;
        if (resultMapping.column != null) {
          numColumns = resultMapping.column.split(",").length;
        }
        int numForeignColumns = 0;
        if (resultMapping.foreignColumn != null) {
          numForeignColumns = resultMapping.foreignColumn.split(",").length;
        }
        if (numColumns != numForeignColumns) {
          throw new IllegalStateException(
              "There should be the same number of columns and foreignColumns in property " + resultMapping.property);
        }
      }
    }

    public Builder column(String column) {
      resultMapping.column = column;
      return this;
    }
  }

  public String getProperty() {
    return property;
  }

  public String getColumn() {
    return column;
  }

View on GitHub (pinned to 008069adb1)

Solutions

1. Count entries in column and foreignColumn and make them match (column="a,b" foreignColumn="x,y").
2. Remove stray spaces or empty segments caused by trailing/double commas in either attribute.
3. If the correlation key is single-column, keep exactly one column and one foreignColumn.

Example fix

<!-- before -->
<association property="author" javaType="Author" resultSet="authorsRS" column="id,tenant" foreignColumn="authorId"/>
<!-- after -->
<association property="author" javaType="Author" resultSet="authorsRS" column="id,tenant" foreignColumn="authorId,authorTenant"/>

int cols = column == null ? 0 : column.split(",").length;
int foreign = foreignColumn == null ? 0 : foreignColumn.split(",").length;
if (resultSet != null && cols != foreign) throw new IllegalArgumentException("column/foreignColumn count mismatch");

When it happens

Trigger: An <association> or <collection> with resultSet="..." where the comma-separated lists in column and foreignColumn differ in length, e.g. column="a,b" with foreignColumn="c".

Common situations: Stored procedures returning multiple result sets joined by composite keys; developer adds one side of a two-part key but not the other; stray/missing commas in the lists.

Related errors

• Two different properties are mapped to the same resultSet
• Error resolving ParameterMode. Cause: {cause}
• Could not find a parent resultMap with id '{extend}'
• Could not find result map '{resultMapName}' referenced from
• Error in result map '{resultMapId}'. Failed to find a constr

AI-assisted analysis of mybatis/mybatis-3@008069adb1 (2026-08-14). Data as JSON: /api/errors/e74656977b9f1e7d. Report an issue: GitHub.