playframework：在播放中将java8 java.time类型LocalDate与冬眠保持一致

Question

I'm having trouble getting any kind of conversion or compatibility working for the new java.time.* types. Or at least, LocalDate.

I see the exception:

play.api.http.HttpErrorHandlerExceptions$$anon$1: Execution exception[[IllegalStateException: Error(s) binding form: {"dateOfBirth":["Invalid value"]}]]
    at play.api.http.HttpErrorHandlerExceptions$.throwableToUsefulException(HttpErrorHandler.scala:265) ~[play_2.11-2.4.4.jar:2.4.4]

Caused by: java.lang.IllegalStateException: Error(s) binding form: {"dateOfBirth":["Invalid value"]}
    at play.data.Form.get(Form.java:592) ~[play-java_2.11-2.4.4.jar:2.4.4]
    at controllers.Application.addPatient(Application.java:49) ~[classes/:na]

There are several methods I've found, that should in principle work, with JPA hibernate, however, if this is a problem (again) of Play or what? I am not sure.

First method:

Provide your own custom converter:

@Converter(autoApply = true)
public class LocalDateAttributeConverter implements AttributeConverter<LocalDate, Date> 
{
    @Override
    public Date convertToDatabaseColumn(LocalDate locDate) {
        return (locDate == null ? null : Date.valueOf(locDate));
    }

    @Override
    public LocalDate convertToEntityAttribute(Date sqlDate) {
        return (sqlDate == null ? null : sqlDate.toLocalDate());
    }
}

Then on the field one needs to use this:

@Convert(converter = LocalDateAttributeConverter.class)
public LocalDate dateOfBirth;

http://www.thoughts-on-java.org/persist-localdate-localdatetime-jpa/

Of course, as I understand it, in principle, I should not need the @Convert annotation since the converter itself is annotated with the @Converter(autoApply = true) annotation. But as I can find no documentation about using successfully Converters with Play (nor any hits on google) I have tried with and without, WITHOUT any success.

Next method:

Well, actually, so far as I read, the newer java8 types should be now supported since hibernate 5 something.... and i've got 5.0.5 in use, and included the necessary library in my class path:

"org.hibernate" % "hibernate-java8" % "5.0.5.Final", 

https://hibernate.atlassian.net/browse/HHH-8844

That didn't help at all. Same stacktrace.

For good measure, I added the hibernate specific annotation

@Type(type="java.time.LocalDate")

to my field.

That would have been ugly. But i'd have put up with it, if it had've helped. It didn't. Same exception. Using that WITH the converter caused other errors. Which is interesting.

I am using Play 2.4, with Hibernate 5.0.5. Has anyone managed to achieve this?

Answer 1

OK, so I finally figured it out. I should have looked more closely (slowly) at the stack-trace.

In fact I in the end was effected by three problems. All solved in three different ways. All, however, related to 'pending' support of the newer java.time classes. To be fair, support from the underlying libraries has only recently been introduced.

First problem: Form binding was failing validation.

I debugged the Form binding work in my controller:

    Form<Patient> form = Form.form(Patient.class);
    form = form.bindFromRequest();
    System.out.println(form.toString());
    Patient patient = form.get();

And while the stacktrace was being caused at the call to form.get() , in fact the error had already occurred at the call to form.bindFromRequest() . Errors were being registered within the Form.errors map, which had come from org.springframework.validation.DataBinder .

A google search further, and I came across this:

https://groups.google.com/forum/#!topic/play-framework/Wl_ip56111c

Implementing that fixed my first problem, and the Form binding then worked.

Second problem: Persistence

I'm' using Hibernate for persistence of the objects. Adding hibernate-java8 to my classpath enables persistence of the new datatype. This, for play 2, goes in your build.sbt file.

libraryDependencies ++= Seq(
  javaJdbc,
  cache,
  javaWs,
  javaJpa,
  "org.hibernate" % "hibernate-entitymanager" % "5.0.5.Final",
  "org.hibernate" % "hibernate-java8" % "5.0.5.Final", 
)

https://hibernate.atlassian.net/browse/HHH-8844

Third problem: Json support

I was unable to render my model instantiation as a Json object. It should be supported, but somehow, in play, it's not setup.

I found this post which showed me how to work-around that:

    // http://stackoverflow.com/questions/32872474/how-to-use-java-time-localdate-on-a-play-framework-json-rest/32891177#comment56814598_32891177
    // https://groups.google.com/forum/?hl=en.#!searchin/play-framework/java.time.localdate/play-framework/Dv-IpvBqWgo/l6NTp3e0BQAJ

The fix I post here for your convenience:

    ObjectMapper mapper = new ObjectMapper();
    mapper.registerModule(new Jdk8Module());
    mapper.registerModule(new JSR310Module());
    mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    Json.setObjectMapper(mapper);

The first and third fixes need to be executed at startup of the application. For play 2.4 the GlobalSettings object has been deprecated, so I'm not sure how they expect you to do this kind of initialization (someone?). However, luckily it will still work. I of course didn't have a Globals class (no longer created by default), so I created the class and pointed my app to it (from the application.conf file) with the following key:

# Minimal global settings to fix form binding and json support of java.time.LocalDate
application.global=GlobalFixes

For your convenience, I post the whole class here, for those who are still learning their way around Playframework

import play.*;
import play.data.format.Formatters;
import play.libs.Json;

import java.time.LocalDate;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import com.fasterxml.jackson.datatype.jsr310.JSR310Module;

import java.text.ParseException;

/**
 * Fixes for play application. TODO remove this once Play has fixed support for LocalDate
 * @author Sean van Buggenum
 *
 */
public class GlobalFixes extends GlobalSettings
{   // One can see from the javadoc of java.time.LocalDate that the toString guarantees this format, regardless of locale!
    private static final Pattern datePattern = Pattern.compile("(\\d\\d\\d\\d)-(\\d\\d)-(\\d\\d)");

    public void onStart(Application app)
    {
        //https://groups.google.com/forum/#!topic/play-framework/Wl_ip56111c
        Formatters.register(LocalDate.class, new Formatters.SimpleFormatter<LocalDate>()
        {
            @Override
            public LocalDate parse(String input, Locale l) throws ParseException
            {
                Matcher m = datePattern.matcher(input);
                if (!m.matches())
                    throw new ParseException("No valid Input for date text: " + input, 0);
                return LocalDate.of(Integer.valueOf(m.group(1)), Integer.valueOf(m.group(2)), Integer.valueOf(m.group(3)));
            }

            @Override
            public String print(LocalDate localTime, Locale l)
            {
                return localTime.toString();
            }
        });

        // Add Json's java 8 support
        // http://stackoverflow.com/questions/32872474/how-to-use-java-time-localdate-on-a-play-framework-json-rest/32891177#comment56814598_32891177
        // https://groups.google.com/forum/?hl=en.#!searchin/play-framework/java.time.localdate/play-framework/Dv-IpvBqWgo/l6NTp3e0BQAJ
        ObjectMapper mapper = new ObjectMapper();
        mapper.registerModule(new Jdk8Module());
        mapper.registerModule(new JSR310Module());
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        Json.setObjectMapper(mapper);
    }
}

I hope that helps some people some time.