CODEWITHSUNDEEP
javamysqlhibernate
Felipe Mosso
Felipe Mosso

Reputation: 3927

How to get values of only one column using Hibernate

I have just started developing using Hibernate and I'm facing an issue while trying to select a column in my table. I have a table which has a column called "nome" and it is an String. All I want to do is to get all values of this column in my table. For this I have created the method:

public List<String> obtemNomePorQuery(String query) {

        EntityManager manager = getEntityManager();

        Session session = manager.unwrap(Session.class);    

        List<String> listResult = (List<String>) session.createQuery(query).list();
        manager.close();

        return listResult;
    }

In this case, I'm passing "select nome from lojas" in query parameter. In MySQL I can run this query and it returns me all I want. Using Hibernate I get the following log:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.hql.internal.ast.QuerySyntaxException: lojas is not mapped [select nome from lojas]
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:656)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
root cause

org.hibernate.hql.internal.ast.QuerySyntaxException: lojas is not mapped [select nome from lojas]
    org.hibernate.hql.internal.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:180)
    org.hibernate.hql.internal.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:110)
    org.hibernate.hql.internal.ast.tree.FromClause.addFromElement(FromClause.java:93)
    org.hibernate.hql.internal.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:326)
    org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3252)
    org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3141)
    org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:694)
    org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:550)
    org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:287)
    org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:235)
    org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:248)
    org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:183)
    org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
    org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:101)
    org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
    org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:119)
    org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:214)
    org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:192)
    org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:1537)
    com.puccamp.projetofinal.persistence.Dao.obtemNomePorQuery(Dao.java:198)
    com.puccamp.projetofinal.controller.LojaController.gerenciaLoja(LojaController.java:63)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    java.lang.reflect.Method.invoke(Unknown Source)
    org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
    org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
    org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

What can I be doing wrongly?

Upvotes: 0

Views: 3391

Answers (1)

le3th4x0rbot
le3th4x0rbot

Reputation: 2451

The method you are using is expecting HQL, not SQL. Is there a persistent object associated with the lojas table? If not HQL is not an option for you, and you will need to instead get a native connection to the database to execute SQL. Have you tried the createSQLQuery(String queryString) method of Session? Here is the javadoc: http://docs.jboss.org/hibernate/orm/3.5/javadoc/org/hibernate/Session.html

Upvotes: 1

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