A simple Json Demo (2)

Building up on the previous demo, I enriched my samples with a method that returns a Json array.

After doing a bit of research, I came up with this solution: my method returns a JsonArray:

...

@GET

@Path("testArray")
@Produces({MediaType.APPLICATION_JSON})
public JsonArray testArray4() throws Exception {

    JsonArray value = Json.createArrayBuilder()
            .add(Json.createObjectBuilder()
                    .add("firstName", "Barak")
                    .add("lastName", "Obama"))
            .add(Json.createObjectBuilder()
                    .add("firstName", "Bill")
                    .add("lastName", "Clinton"))
            .build();
    return value;
}

...

It is available under http://localhost:8080/demoRest/demo/testArray

Note that the deployment occurs using the exploded war of IntelliJ on Glassfish 4.1, which allows defining a custom context root under "/". Otherwise, the *.war file being (oddly) DemoBean_war.war, the URL would be http://localhost:8080/DemoBean_war/demoRest/demo/testArray.

I first made diverse other attempts, which all failed because of the internal binding that takes place during Json processing: using a list of dtos, a list of JsonObject, or a list of dtos wrapped in a GenericEntity: all attempt failed with diverse errors in relations with the libraries available on the server:

java.lang.NoClassDefFoundError: 

  javax/xml/parsers/ParserConfigurationException

java.lang.NoClassDefFoundError: 

  Could not initialize class org.eclipse.persistence.jaxb.BeanValidationHelper

java.lang.ClassNotFoundException: 

  javax.xml.parsers.ParserConfigurationException not found by org.eclipse.persistence.moxy

The solution using a Json Array proved to be working on Glassfish 4.1.1

I found some information about incompatibilities in Jersey Libs of Glasshfish 4.1.1 on the Jersey Jira, but none helped me solving the problems.

I found a hint in Adam's Bien Blog for returning a list of objects with JAX-RS, but this didn't solve the problems that occured when running on Glassfish. 

I also could not deploy successfully the examples on JBoss, but did not investigate further.

A simple, simple json and rest demo

I created a simple demonstration of a Rest - application, based on the examples from the Java EE Tutorial.

My demo just returns a Json object.

I used IntelliJ, configuring module facets for library dependencies.

I did not use any maven for build or dependency management.

Deployment is done on a local Glassfish instance.

Project configuration IntelliJ

Project settings use the facets EJB, Web and Java EE application. Libraries : ejb 3.2, javax.json.processing-1.0, JAX-RS.

Code

Code consists of 2 classes : one application - Class (that inherits from javax.ws.rs.core.Application), and one implementation class, where the json processing takes place, and with the rest annotations.

Application class

package org.nstern.demos.rest;

import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;

@ApplicationPath("/demoRest")
  public class RestDemoApplication extends Application {
}

Implementing class

package org.nstern.demos.rest;

import javax.json.Json;
import javax.json.JsonObject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.UriInfo;

@Path("/demo")
public class RestDemoResource {

    @Context    private UriInfo context;

    public RestDemoResource(){}

    @GET    

    @Path("test")
    @Produces({MediaType.APPLICATION_JSON})
    public String testBean() {
        return "123456789";
    }

    @GET    

    @Path("testJson")
    @Produces({MediaType.APPLICATION_JSON})
    public JsonObject testJson() {

        JsonObject model = Json.createObjectBuilder()
                .add("firstName", "Duke")
                .add("lastName", "Java")
                .build();

        return model;
    }
}

Deployment and calling the Rest methods

Artefact is configured in IntelliJ in the Glassfish config (war exploded). I defined a custom context root to avoid cumbersome URLs.

I call the rest method using Chrome advanced rest client:

The two urls are :

http://localhost:8080/demoRest/demo/test

http://localhost:8080/demoRest/demo/testJson

Summary, remarks

I had to struggle before finding out that if I don't define a custom context root, the application will use a strange root URL  - like "http://localhost:8080/demoBean_war_exploded/etc.*"

I found a useful hint about generating artefacts (*.war file) on this blog. (This is pure handling of IntelliJ).

Not that this application has no web.xml

How to validate an input field with Angular JS

Angular JS offers a very simple way to validate an entry into an input field with a regular expression with the ng-pattern attribute.

I had to change a behavior of an input field in an application: special characters like 'ä', 'ö', 'ü' were not allowed, but should have.

The interesting thing is that the pattern can be assigned dynamically.

Here is the setup:

for a static pattern, I use a variable (vm.regex) in my controller.

(function () {
    var valApp = angular.module("valApp", []);
    valApp.controller("ListCtrl", ListController);
    function ListController() {
        var vm = this;
        vm.regex ='\\d+';
        ...
    }
})();

... and in the view, the attribute ng-pattern references this variable: 

<div class="container" ng-app="valApp">

  <div class="row" ng-controller="ListCtrl as ctrl">

    <form name="myForm">

      <div class="span4">

          <p>

            <label>Field1:</label>

            <input name="field1" 

            type="text" 

            ng-model="ctrl.item.field1" 

            ng-pattern="'\\d'"/>

          </p>

          <p>

            <label>Field2:</label>

            <input name="field2" 

            type="text" 

            ng-model="ctrl.item.field2" 

            ng-pattern="ctrl.regex"/>

          </p>

      </div>

    </form>

  </div>

</div>

Now, the pattern to allow characters with "Umlauten" (ä,ü,ö) is as follows:

[a-zA-Z0-9öüäÖÜÄ]+