JPA：名称的查询名称：...未找到

Question

我正在使用JPA在我的公司开发多租户应用程序。所以我使用TABLE_PER_TENANT功能将租户特定数据分成不同的模式。将数据推入数据库是没有问题的，可以正常工作。问题只是从数据库中读取数据，应用程序找不到我的命名查询。

我已经尝试过不同的东西：

• 重新编译和部署应用程序
• 移动的persistence.xml到不同的文件夹
• 经过错误日志和调试的整个应用程序，无法找到其原因
• 只好看看所有可能的解决方案，我可以找到关于谷歌和尝试他们...

我在这里错过了什么？有任何想法吗？

BaseObject.java

@MappedSuperclass 
@Multitenant(MultitenantType.TABLE_PER_TENANT) 
@TenantTableDiscriminator(type = TenantTableDiscriminatorType.SCHEMA, contextProperty="tenant.id") 
public abstract class BaseObject { 

    /** 
    * The (globally unique) ID of the object. 
    */ 
    @Id 
    @Column(name = "GUID", length = 36) 
    private String guid = UUID.randomUUID().toString(); 

    /** 
    * The {@link Date} the object was created at. 
    */ 
    @Temporal(TemporalType.TIMESTAMP) 
    @Column(name = "CREATION_DATE", updatable = false) 
    private Date createdAt = null; 

    /** 
    * The {@link Date} the object was last modified at. 
    */ 
    @Temporal(TemporalType.TIMESTAMP) 
    @Column(name = "MODIFICATION_DATE") 
    private Date lastModifiedAt = null; 

    /** 
    * ID of the user who created the object. 
    */ 
    @Column(name = "CREATED_BY", updatable = false, length = 20) 
    private String createdBy = null; 

    /** 
    * ID of the user who was the last to modify the object. 
    */ 
    @Column(name = "MODIFIED_BY", length = 20) 
    private String lastModifiedBy = null; 

    // Methods... 
} 

Plant.java

@Entity 
@Table(name = "PLANT_POLLUTION_DATA") 
@NamedQueries({ @NamedQuery(name = "Plant.getPlants", query = "SELECT c FROM Plant c"), 
       @NamedQuery(name = "Plant.getPlantById", query = "SELECT c FROM Plant c WHERE c.id = :id") }) 

@XmlRootElement(name = "plantlist") 
@XmlAccessorType(XmlAccessType.FIELD) 
public class Plant extends BaseObject implements Serializable { 

    /** 
    * The <code>serialVersionUID</code> of the {@link Plant} class. 
    */ 
    private static final long serialVersionUID = 1L; 

    @Column(name = "ID", length = 36, nullable = true) 
    String id = null; 

    @Column(name = "O3", length = 10, nullable = true) 
    String o3 = null; 

    @Column(name = "DATE_FIELD") 
    java.sql.Date dateField = null; 

    @Column(name = "location", length = 36, nullable = true) 
    String location = null; 

    // Methods... 
} 

NamedQuery调用

String tenantId = getTenantId(); 
Map<String, String> props = new HashMap<String, String>(); 
props.put("tenant.id", tenantId); 
EntityManager em = this.getEntityManagerFactory().createEntityManager(props); 
Query query = em.createNamedQuery("Plant.getPlantById"); 
query.setParameter("id", id); 
retVal = query.getResultList(); 

周的persistence.xml（位于 “file.war/WEB-INF /类/ META-INF/persistence.xml中”）

<?xml version="1.0" encoding="UTF-8"?> 
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"> 
    <persistence-unit name="pollutionmonitoring" transaction-type="RESOURCE_LOCAL"> 
     <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> 
     <class>com.company.cloud.samples.pollutionmonitoring.model.BaseObject</class> 
     <class>com.company.cloud.samples.pollutionmonitoring.model.Plant</class> 
     <properties> 
      <property name="eclipselink.ddl-generation" value="create-or-extend-tables"/> 
     </properties> 
    </persistence-unit> 
</persistence> 

Answer 1

我可以只通过添加以下2行代码解决这个问题自己：

... 
EntityManager em = this.getEntityManagerFactory().createEntityManager(props); 

em.getTransaction().begin(); 
em.getTransaction().commit(); 

Query query = em.createNamedQuery("Plant.getPlantById"); 
... 

我不知道这个变化究竟，但它为我工作:)也许有人知道为什么这个解决方案确实工作？

PS：我只是从另一个类中复制它，我必须将数据添加到数据库，这是两个类之间的唯一区别。