java - 无法解决属性查询异常

Question

当我尝试显示来自 EmergencyContact 的数据时，出现以下异常。 SurveyData 和 EmergencyData 通过 OneToMany 关联。我能够保留数据，但无法将其检索回来。

我想提供一个 SurveyID 作为输入并获取该调查的紧急联系人。我验证了所有的 setter 和 getter 方法，它们看起来没问题。我无法追踪我在哪里犯了错误。如有任何帮助，我们将不胜感激。

16:53:42,029 ERROR [stderr] (http-localhost-127.0.0.1-8080-1) Caused by: org.hibernate.QueryException: could not resolve property: survey_id of: masonsurveyejb.businesslogic.EmergencyContact [SELECT emc FROM masonsurveyejb.businesslogic.EmergencyContact emc WHERE emc.survey_id = 11]

我的查询字符串如下所示。我收到 Survey_id 变量值作为此方法中的参数。

"SELECT emc FROM EmergencyContact emc WHERE emc.survey_id = " + survey_id

以下是我的 EmergencyContact 和 SurveyData 类

package masonsurveyejb.businesslogic;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;

@Entity
@Table(name = "EmergencyData")
public class EmergencyContact implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @SequenceGenerator(name = "EMERGENCY_SEQUENCE", sequenceName = "Survey_Seq", initialValue = 100, allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "EMERGENCY_SEQUENCE")
    private Integer contactId;
    @Column(name = "Name")
    private String emName;
    @Column(name = "Phone")
    private String emPhone;
    @Column(name = "Email")
    private String emEmail;

    @ManyToOne
    @JoinColumn(name = "SurveyID")
    private SurveyData surveyData;

    public Integer getContactId() {
        return contactId;
    }

    public void setContactId(Integer contactId) {
        this.contactId = contactId;
    }

    public SurveyData getSurveyData() {
        return surveyData;
    }

    public void setSurveyData(SurveyData surveyData) {
        this.surveyData = surveyData;
    }

    public String getEmName() {
        return emName;
    }

    public void setEmName(String emName) {
        this.emName = emName;
    }

    public String getEmPhone() {
        return emPhone;
    }

    public void setEmPhone(String emPhone) {
        this.emPhone = emPhone;
    }

    public String getEmEmail() {
        return emEmail;
    }

    public void setEmEmail(String emEmail) {
        this.emEmail = emEmail;
    }
}


///////////////////////////////////////////////////////////////////////////////
// @filename: Student.java
// @description: This file is the a simple class which is used as a model
//               object for Student.
// 
// Modification History
// Date        Author                   Change Reason
// ====        ======                   =============
// 2014-02-20  Santosh K Tadikonda      Initial Creation
//
///////////////////////////////////////////////////////////////////////////////

package masonsurveyejb.businesslogic;

import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.SequenceGenerator;

@Entity
public class SurveyData {

    @Id
    @SequenceGenerator(name = "SURVEY_SEQUENCE", sequenceName = "Survey_Seq", initialValue = 100, allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SURVEY_SEQUENCE")
    @Column(name = "SurveyID")
    private Integer survey_id;
    private String firstname;
    private String lastname;
    private String address;
    private String city;
    private String state;
    private String zipcode;
    private String telephone;
    private String email;
    private String surveydate;
    @Column(name = "Likes")
    private String chklike;
    @Column(name = "Know")
    private String radioknow;
    private String recommend;
    private String raffle;
    private String comments;

    @OneToMany(mappedBy = "surveyData", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private List<EmergencyContact> emContacts;

    public List<EmergencyContact> getEmContacts() {
        return emContacts;
    }

    public void setEmContacts(List<EmergencyContact> emContacts) {
        this.emContacts = emContacts;
    }

    public Integer getSurvey_id() {
        return survey_id;
    }

    public void setSurvey_id(Integer survey_id) {
        this.survey_id = survey_id;
    }

    public String getFirstname() {
        return firstname;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }

    public String getLastname() {
        return lastname;
    }

    public void setLastname(String lastname) {
        this.lastname = lastname;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getZipcode() {
        return zipcode;
    }

    public void setZipcode(String zipcode) {
        this.zipcode = zipcode;
    }

    public String getTelephone() {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getSurveydate() {
        return surveydate;
    }

    public void setSurveydate(String surveydate) {
        this.surveydate = surveydate;
    }

    public String getChklike() {
        return chklike;
    }

    public void setChklike(String chklike) {
        this.chklike = chklike;
    }

    public String getRadioknow() {
        return radioknow;
    }

    public void setRadioknow(String radioknow) {
        this.radioknow = radioknow;
    }

    public String getRecommend() {
        return recommend;
    }

    public void setRecommend(String recommend) {
        this.recommend = recommend;
    }

    public String getRaffle() {
        return raffle;
    }

    public void setRaffle(String raffle) {
        this.raffle = raffle;
    }

    public String getComments() {
        return comments;
    }

    public void setComments(String comments) {
        this.comments = comments;
    }

    public String toString() {

        String studentString;

        studentString = getSurvey_id() + ";" +getFirstname() + ";" + getLastname() + ";"
                + getAddress() + ";" + getCity() + ";" + getState() + ";"
                + getZipcode() + ";" + getTelephone() + ";" + getEmail() + ";"
                + getSurveydate() + ";" + getChklike() + ";" + getRadioknow()
                + ";" + getRecommend() + ";" + getRaffle() + ";"
                + getComments();

        return studentString;
    }
}

以下是我进行查询的方法

@Override
    public ArrayList<EmergencyContact> GetEmergencyContacts(String survey_id) {

        try {

            if (survey_id == null || survey_id.length() == 0) {
                System.out.println("Received a null or empty survey ID.");
                return null;
            }

            System.out.println("Getting emergency contacts for " + survey_id);
            String queryStr = "SELECT emc FROM EmergencyContact emc WHERE emc.survey_id = "
                    + survey_id;
            Query query = entityManager.createQuery(queryStr);
            List resultList = query.getResultList();

            if (resultList != null && resultList.size() > 0) {
                ArrayList<EmergencyContact> emList = new ArrayList<EmergencyContact>();
                for (Object result : resultList) {
                    EmergencyContact emc = new EmergencyContact();
                    emc = (EmergencyContact) result;
                    emList.add(emc);
                }

                return emList;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

Answer 1

您收到异常，因为实体“EmergencyContact”没有名为“survey_id”的属性。

您的查询应该是:

String queryStr = "SELECT emc FROM EmergencyContact emc WHERE emc.surveyData.survey_id = :id";
Query query = entityManager.createQuery(queryStr).setParameter("id", survey_id);
List resultList = query.getResultList();

请考虑两件事:

1. 在 JPQL 查询中使用属性名称 (surveyData.survey_id)
2. 最好使用特殊方法“setParameter”设置查询参数