[英]JPA CriteriaBuilder Joins with extra ON clause parameters (predicate)
[英]CriteriaBuilder in JPA - where clause
是JPA的新手。 使用where子句构建选择查询。 我需要从表Contacts中选择所有等于String名称值的ContactName。
使用以下代码创建数据库表:
CREATE TABLE Contacts (
ContactId BIGINT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
ContactName VARCHAR(100) NOT NULL,
ContactEmailID VARCHAR(100) NOT NULL,
UserName VARCHAR(100) NOT NULL,
INDEX Contact_Names (ContactName)
) ENGINE = InnoDB;
以下是我的Entity类;
@Entity
private String UserName;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "ContactId")
public long getContactId() {
return ContactId;
}
public void setContactId(long contactId) {
ContactId = contactId;
}
@Basic
@Column(name = "UserName")
public String getUserName() {
return UserName;
}
public void setUserName(String UserName) {
this.UserName = UserName;
}
以下是我试图编写CriteriaBuilder代码的ContactServlet类代码。
EntityManager manager = null;
EntityTransaction transaction = null;
try{
manager = this.factory.createEntityManager();
transaction = manager.getTransaction();
transaction.begin();
CriteriaBuilder cb = manager.getCriteriaBuilder();
CriteriaQuery<Contact> q1 = cb.createQuery(Contact.class);
Root<Contact> postRoot = q1.from(Contact.class);
q1.select(postRoot).where(cb.equal(postRoot.get("UserName"), name));
TypedQuery<Contact> qry = manager.createQuery(q1);
List<Contact> result = qry.getResultList();
for (Contact contactInstance : result)
{
DBContactName = contactInstance.getContactName().trim();
DBContactEmail = contactInstance.getContactEmailID().trim();
.....
不知道我要去哪里错了吗?
以下是执行我的项目时的错误:java.lang.IllegalArgumentException:无法针对org.hibernate上org.hibernate.jpa.criteria.path.AbstractPathImpl.unknownAttribute(AbstractPathImpl.java:117)上的路径解析属性[UserName]。 org.hibernate.jpa.criteria.path.AbstractPathImpl.get(AbstractPathImpl.java:185)的com.ContactServlet.doPost(ContactServlet.java:110)的jpa.criteria.path.AbstractPathImpl.locateAttribute(AbstractPathImpl.java:214)在org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java)在javax.servlet.http.HttpServlet.service(HttpServlet.java:725)在javax.servlet.http.HttpServlet.service(HttpServlet.java:644) :291),位于org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52),位于org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52),位于org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)。 org.apache.catalina.core.Applicat上的core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) 位于org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)的org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)的ionFilterChain.doFilter(ApplicationFilterChain.java:206) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)处的.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve .java:79)位于org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)位于org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)位于org.apache.catalina。 org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1081)的org.apache.coyote.AbstractProtocol $ AbstractConnectionHandler.process(AbstractProtocol.java:658)的connector.CoyoteAdapter.service(CoyoteAdapter.java:534)在org.apache.coyote.http11.Http11NioProtocol $ Http11ConnectionHandle org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun(NioEndpoint.java:1566)的r.process(Http11NioProtocol.java:222)org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.run( NioEndpoint.java:1523),位于java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142),位于org.apache.tomcat.util,java.util.concurrent.ThreadPoolExecutor $ Worker.run(ThreadPoolExecutor.java:617) .threads.TaskThread $ WrappingRunnable.run(TaskThread.java:61)位于java.lang.Thread.run(Thread.java:745)
尝试:
q1.select(postRoot).where(cb.equal(postRoot.get("userName"), name));
UserName属性的u小写。
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