Преобразование объектов JPA в карту

Question

Я довольно новичок в JPA и базах данных в целом, и я пытаюсь научить себя этому. Я хочу знать, возможно ли вообще превратить список, который вы извлекаете из определенного объекта в карту. В конечном итоге я хочу получить список карт всех отдельных объектов.

Это ошибка, что я получаю:

java.lang.ClassCastException: consultant.billing.entity.WorkEntry cannot be cast to java.util.Map 

Ниже мое лицо и код, который я пытаюсь запустить:

@Entity 
@Table(name = "work_entry") 
@XmlRootElement 
@NamedQueries({ 
@NamedQuery(name = "WorkEntry.findAll", query = "SELECT w FROM WorkEntry w"), 
@NamedQuery(name = "WorkEntry.findByWorkEntryId", query = "SELECT w FROM WorkEntry w WHERE w.workEntryId = :workEntryId"), 
@NamedQuery(name = "WorkEntry.findByDate", query = "SELECT w FROM WorkEntry w WHERE w.date = :date"), 
@NamedQuery(name = "WorkEntry.findByHoursWorked", query = "SELECT w FROM WorkEntry w WHERE w.hoursWorked = :hoursWorked")}) 
public class WorkEntry implements Serializable { 
private static final long serialVersionUID = 1L; 
@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@Basic(optional = false) 
@Column(name = "work_entry_id") 
private Integer workEntryId; 
@Column(name = "date") 
@Temporal(TemporalType.DATE) 
private Date date; 
// @Max(value=?) @Min(value=?)//if you know range of your decimal fields consider using these annotations to enforce field validation 
@Column(name = "hours_worked") 
private Double hoursWorked; 
@JoinColumn(name = "activity_id", referencedColumnName = "activity_id") 
@ManyToOne 
private Activity activityId; 
@JoinColumn(name = "customer_id", referencedColumnName = "customer_id") 
@ManyToOne 
private Customer customerId; 

public WorkEntry() { 
} 

public WorkEntry(Date date, Double hoursWorked, Customer customerId, Activity activityId) { 
    this.date = date; 
    this.hoursWorked = hoursWorked; 
    this.activityId = activityId; 
    this.customerId = customerId; 
} 


public WorkEntry(Integer workEntryId) { 
    this.workEntryId = workEntryId; 
} 

public Integer getWorkEntryId() { 
    return workEntryId; 
} 

public void setWorkEntryId(Integer workEntryId) { 
    this.workEntryId = workEntryId; 
} 

public Date getDate() { 
    return date; 
} 

public void setDate(Date date) { 
    this.date = date; 
} 

public Double getHoursWorked() { 
    return hoursWorked; 
} 

public void setHoursWorked(Double hoursWorked) { 
    this.hoursWorked = hoursWorked; 
} 

public Activity getActivityId() { 
    return activityId; 
} 

public void setActivityId(Activity activityId) { 
    this.activityId = activityId; 
} 

public Customer getCustomerId() { 
    return customerId; 
} 

public void setCustomerId(Customer customerId) { 
    this.customerId = customerId; 
} 

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

@Override 
public boolean equals(Object object) { 
    // TODO: Warning - this method won't work in the case the id fields are not set 
    if (!(object instanceof WorkEntry)) { 
     return false; 
    } 
    WorkEntry other = (WorkEntry) object; 
    if ((this.workEntryId == null && other.workEntryId != null) || (this.workEntryId != null && !this.workEntryId.equals(other.workEntryId))) { 
     return false; 
    } 
    return true; 
} 

@Override 
public String toString() { 
    return "consultant.billing.entity.WorkEntry[ workEntryId=" + workEntryId + " ]"; 
} 

}

@Entity 
@Table(name = "customer") 
@XmlRootElement 
@NamedQueries({ 
@NamedQuery(name = "Customer.findAll", query = "SELECT c FROM Customer c"), 
@NamedQuery(name = "Customer.findByCustomerId", query = "SELECT c FROM Customer c WHERE c.customerId = :customerId"), 
@NamedQuery(name = "Customer.findByFirstName", query = "SELECT c FROM Customer c WHERE c.firstName = :firstName"), 
@NamedQuery(name = "Customer.findByLastName", query = "SELECT c FROM Customer c WHERE c.lastName = :lastName"), 
@NamedQuery(name = "Customer.findByStreetAddress", query = "SELECT c FROM Customer c WHERE c.streetAddress = :streetAddress"), 
@NamedQuery(name = "Customer.findByCity", query = "SELECT c FROM Customer c WHERE c.city = :city"), 
@NamedQuery(name = "Customer.findByState", query = "SELECT c FROM Customer c WHERE c.state = :state"), 
@NamedQuery(name = "Customer.findByPostalCode", query = "SELECT c FROM Customer c WHERE c.postalCode = :postalCode"), 
@NamedQuery(name = "Customer.findByPhoneNumber", query = "SELECT c FROM Customer c WHERE c.phoneNumber = :phoneNumber"), 
@NamedQuery(name = "Customer.findByEmail", query = "SELECT c FROM Customer c WHERE c.email = :email")}) 
public class Customer implements Serializable { 
private static final long serialVersionUID = 1L; 
@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@Basic(optional = false) 
@Column(name = "customer_id") 
private Integer customerId; 
@Size(max = 75) 
@Column(name = "first_name") 
private String firstName; 
@Size(max = 75) 
@Column(name = "last_name") 
private String lastName; 
@Size(max = 250) 
@Column(name = "street_address") 
private String streetAddress; 
@Size(max = 50) 
@Column(name = "city") 
private String city; 
@Size(max = 50) 
@Column(name = "state") 
private String state; 
@Size(max = 45) 
@Column(name = "postal_code") 
private String postalCode; 
@Size(max = 45) 
@Column(name = "phone_number") 
private String phoneNumber; 
// @Pattern(regexp="[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?", message="Invalid email")//if the field contains email address consider using this annotation to enforce field validation 
@Size(max = 250) 
@Column(name = "email") 
private String email; 
@OneToMany(mappedBy = "customerId") 
private Collection<ExpenseEntry> expenseEntryCollection; 
@OneToMany(mappedBy = "customerId") 
private Collection<WorkEntry> workEntryCollection; 

код I 'm пытается запустить:

public Customer() { 
} 

String customerId = request.getParameter("customerId"); 
      Customer customer = customerServ.find(Integer.parseInt(customerId)); 
      request.setAttribute("customer", customer); 

      String sDate = request.getParameter("sDate"); 
      Date parsedSDate = sdf.parse(sDate); 
      java.sql.Date sqlSDate = new java.sql.Date(parsedSDate.getTime()); 

      String eDate = request.getParameter("eDate"); 
      Date parsedEDate = sdf.parse(eDate); 
      java.sql.Date sqlEDate = new java.sql.Date(parsedEDate.getTime()); 

      List<Map> workDone = workServ.getWorkDoneByCustAndDate(Integer.parseInt(customerId), sqlSDate, sqlEDate); 
      List<Map> expenses = expenseEntServ.getExpenseForCustIdAndDate(Integer.parseInt(customerId), sqlSDate, sqlEDate); 

      List newInvoice = invoice.getInvoice(workDone,expenses); 

метод я использую, чтобы получить WorkEntry:

public List<Map> getWorkDoneByCustAndDate(int custId, Date sDate, Date eDate) { 
    String jpql = "SELECT w FROM WorkEntry w WHERE w.customerId.customerId = :customerId AND w.date BETWEEN :sDate AND :eDate"; 
    Query q = getEntityManager().createQuery(jpql); 
    q.setParameter("customerId", custId); 
    q.setParameter("sDate", sDate, TemporalType.DATE); 
    q.setParameter("eDate", eDate, TemporalType.DATE); 
    return q.getResultList(); 
} 

Answer 1

Вы можете сделать это, но не с JPA, после того, как вы получите список ваших записей работы, вы можете использовать Java отражение или более проще, использовать BeanUtils или JACKSON для преобразования любого Java Bean (в вашем случае, класса WorkEntry) в карту.

Вы можете увидеть этот пример библиотеки BeanUtils для достижения этой цели.

beanUtils example

Вы можете добавить этот код после того, как вы получите список:

List<Map> yourList=new ArrayList<Map>(); 
    List<WorkEntry> list=q.getResultList(); 
    for(WorkEntry we:list){ 
     BeanMap map=new BeanMap(we); 
     yourList.add(map); 
    } 

Надеется, что это помогает.