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Converter String para Objeto

Referente ao curso Spring MVC I: Criando aplicações web

por Carlos Evangelista Reis
| 335.2k xp | 203 posts

Qual a melhor forma de converter uma string(id) que vem do formulário em um objeto?

2 respostas
solução!
por Alberto Souza
| 2676.6k xp | 5740 posts
Instrutor Desenvolvedor e Instrutor

Você pode receber ela como Integer ou Long no método do seu Controller :). Caso você queira um objeto do seu negócio mesmo, como um usuário, o melhor é vc pegar esse id e carregar o objeto do banco.

por Carlos Evangelista Reis
| 335.2k xp | 203 posts

E ai Albert blz?

Então cara, estou fazendo da seguinte forma. Criei uma classe que faz essa conversão buscando o "Autor" pelo id no banco, e no controller eu chamo essa classe através de um método anotado com "@InitBinder". Até então funciona normal, porém quando eu abro o formulário escolho um autor e envio o formulário sem os outros campos, dá erro, e quando faço a mesma coisa em outro campo as validações acontecem normalmente.

git: https://github.com/CarlosEReis/MinhaLivraria

AutorConverter

package br.com.carlosreis.minhaloja.models;

import java.beans.PropertyEditorSupport;

import br.com.carlosreis.minhaloja.Daos.AutorDao;

public class AutorConverter extends PropertyEditorSupport {

    private AutorDao autorDao;

    public AutorConverter(AutorDao autorDao) {
        this.autorDao = autorDao;
    }

    @Override
    public void setAsText(String id) throws IllegalArgumentException {
        Long idAutor = new Long(id);
        Autor autor = this.autorDao.busca(idAutor);
        this.setValue(autor);
    }

}

LivroController

package br.com.carlosreis.minhaloja.controllers;

import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.ServletRequestDataBinder;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

import br.com.carlosreis.minhaloja.Daos.AutorDao;
import br.com.carlosreis.minhaloja.Daos.LivroDao;
import br.com.carlosreis.minhaloja.models.Autor;
import br.com.carlosreis.minhaloja.models.AutorConverter;
import br.com.carlosreis.minhaloja.models.Livro;

@Controller
@RequestMapping("/livro")
public class LivroController {

    @Autowired
    private LivroDao livroDao;

    @Autowired
    private AutorDao autorDao;

    @InitBinder
    public void initBinder(HttpServletRequest request, ServletRequestDataBinder binder) {
        binder.registerCustomEditor(Autor.class, new AutorConverter(autorDao));
    }

    @GetMapping("novo")
    public ModelAndView form(Livro livro) {
        ModelAndView mv = new ModelAndView("livro/form");
        List<Autor> autores = autorDao.lista();
        mv.addObject("autores", autores);
        return mv;
    }

    @PostMapping
    public ModelAndView gravar(@Valid Livro livro, BindingResult result, RedirectAttributes redirectAttributes) {

        System.out.println(livro);

        if (result.hasErrors()) {
            return form(livro);
        }

        livroDao.gravar(livro);
        redirectAttributes.addAttribute("menssage", "Livro" + livro.getNome() + " salvo com sucesso.");
        return new ModelAndView("livro/ok");
    }

}

Erro

mar 06, 2017 1:06:50 PM org.apache.catalina.core.ApplicationDispatcher invoke
GRAVE: Servlet.service() for servlet jsp threw exception
java.lang.NumberFormatException: For input string: "autor"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Long.parseLong(Long.java:589)
    at java.lang.Long.<init>(Long.java:965)
    at br.com.carlosreis.minhaloja.models.AutorConverter.setAsText(AutorConverter.java:17)
    at org.springframework.web.servlet.tags.form.SelectedValueComparator.exhaustiveCompare(SelectedValueComparator.java:173)
    at org.springframework.web.servlet.tags.form.SelectedValueComparator.isSelected(SelectedValueComparator.java:98)
    at org.springframework.web.servlet.tags.form.OptionTag.isSelected(OptionTag.java:238)
    at org.springframework.web.servlet.tags.form.OptionTag.renderOption(OptionTag.java:202)
    at org.springframework.web.servlet.tags.form.OptionTag.renderDefaultContent(OptionTag.java:144)
    at org.springframework.web.servlet.tags.form.AbstractHtmlElementBodyTag.doEndTag(AbstractHtmlElementBodyTag.java:69)
    at org.apache.jsp.WEB_002dINF.views.livro.form_jsp._jspService(form_jsp.java:308)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:726)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:469)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:394)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:311)
    at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
    at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1257)
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:798)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1434)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

mar 06, 2017 1:06:50 PM org.apache.catalina.core.StandardWrapperValve invoke
GRAVE: Servlet.service() for servlet [dispatcher] in context with path [/minhalivraria] threw exception [java.lang.NumberFormatException: For input string: "autor"] with root cause
java.lang.NumberFormatException: For input string: "autor"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Long.parseLong(Long.java:589)
    at java.lang.Long.<init>(Long.java:965)
    at br.com.carlosreis.minhaloja.models.AutorConverter.setAsText(AutorConverter.java:17)
    at org.springframework.web.servlet.tags.form.SelectedValueComparator.exhaustiveCompare(SelectedValueComparator.java:173)
    at org.springframework.web.servlet.tags.form.SelectedValueComparator.isSelected(SelectedValueComparator.java:98)
    at org.springframework.web.servlet.tags.form.OptionTag.isSelected(OptionTag.java:238)
    at org.springframework.web.servlet.tags.form.OptionTag.renderOption(OptionTag.java:202)
    at org.springframework.web.servlet.tags.form.OptionTag.renderDefaultContent(OptionTag.java:144)
    at org.springframework.web.servlet.tags.form.AbstractHtmlElementBodyTag.doEndTag(AbstractHtmlElementBodyTag.java:69)
    at org.apache.jsp.WEB_002dINF.views.livro.form_jsp._jspService(form_jsp.java:308)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:726)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:469)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:394)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:311)
    at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
    at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1257)
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:798)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1434)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)