EclipseLink native query result into POJO - Missing descriptor for [Class]

Question

I\'m using EclipseLink to run some Native SQL. I need to return the data into a POJO. I followed the instructions at EclipseLink Docs, but I receive the error Missing

Answer 1

Old question but may be following solution will help someone else.

Suppose you want to return a list of columns, data type and data length for a given table in Oracle. I have written below a native sample query for this:

  private static final String TABLE_COLUMNS = "select utc.COLUMN_NAME, utc.DATA_TYPE, utc.DATA_LENGTH "
        + "from user_tab_columns utc "
        + "where utc.table_name = ? "                
        + "order by utc.column_name asc";

Now the requirement is to construct a list of POJO from the result of above query.

Define TableColumn entity class as below:

@Entity
public class TableColumn implements Serializable {

@Id
@Column(name = "COLUMN_NAME")
private String columnName;
@Column(name = "DATA_TYPE")
private String dataType;
@Column(name = "DATA_LENGTH")
private int dataLength;

public String getColumnName() {
    return columnName;
}

public void setColumnName(String columnName) {
    this.columnName = columnName;
}

public String getDataType() {
    return dataType;
}

public void setDataType(String dataType) {
    this.dataType = dataType;
}

public int getDataLength() {
    return dataLength;
}

public void setDataLength(int dataLength) {
    this.dataLength = dataLength;
}

public TableColumn(String columnName, String dataType, int dataLength) {
    this.columnName = columnName;
    this.dataType = dataType;
    this.dataLength = dataLength;
}

public TableColumn(String columnName) {
    this.columnName = columnName;
}

public TableColumn() {
}

@Override
public int hashCode() {
    int hash = 0;
    hash += (columnName != null ? columnName.hashCode() : 0);
    return hash;
}

@Override
public boolean equals(Object object) {

    if (!(object instanceof TableColumn)) {
        return false;
    }
    TableColumn other = (TableColumn) object;
    if ((this.columnName == null && other.columnName != null) || (this.columnName != null && !this.columnName.equals(other.columnName))) {
        return false;
    }
    return true;
}

@Override
public String toString() {
    return getColumnName();
}

}

Now we are ready to construct a list of POJO. Use the sample code below to construct get your result as List of POJOs.

public List findTableColumns(String table) {
    List listTables = new ArrayList<>();
    EntityManager em = emf.createEntityManager();
    Query q = em.createNativeQuery(TABLE_COLUMNS, TableColumn.class).setParameter(1, table);
    listTables = q.getResultList();
    em.close();
    return listTables;
}