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How to build a simple blog application with JHipster 4.0.5

Get started with JHipster 4

Matt Raible
JHipster 4
Solar eclipse image via Shutterstock

In this article, Matt Raible , a web developer and Java Champion, shows you how to build a simple blog application with JHipster 4.0.5.

What is JHipster?

JHipster is one of those open-source projects you stumble upon and immediately think, “Of course!” It combines three very successful frameworks in web development: Bootstrap, Angular, and Spring Boot. Bootstrap was one of the first dominant web-component frameworks. Its largest appeal was that it only required a bit of HTML and it worked! All the efforts we made in the Java community to develop web components were shown a better path by Bootstrap. It leveled the playing field in HTML/CSS development, much like Apple’s Human Interface Guidelines did for iOS apps.

JHipster was started by Julien Dubois in October 2013 (Julien’s first commit was on October 21, 2013). The first public release (version 0.3.1) was launched December 7, 2013. Since then, the project has had over 115 releases! It is an open-source, Apache 2.0-licensed project on GitHub. It has a core team of 16 developers and over 280 contributors. You can find its homepage at http://jhipster.github.io. If you look at the project on GitHub, you can see it’s mostly written in JavaScript (42%) and Java (27%).

At its core, JHipster is a Yeoman generator. Yeoman is a code generator that you run with a yo command to generate complete applications or useful pieces of an application. Yeoman generators promote what the Yeoman team calls the “Yeoman workflow”. This is an opinionated client-side stack of tools that can help developers quickly build beautiful web applications. It takes care of providing everything needed to get working without the normal pains associated with a manual setup.

JHipster 4 is the same JHipster many developers know and love, with a couple bright and shiny new features: namely Angular and Bootstrap 4 support.

NOTE: When I say “AngularJS”, I mean Angular 1.x. “Angular” is the forward-looking name for Angular 2 and beyond.

Install JHipster 4

The Installing JHipster instructions show you all the tools you’ll need to use a released version of JHipster.

  1. Install Java 8 from Oracle.
  2. Install Git from https://git-scm.com.
  3. Install Node.js from http://nodejs.org. I used Node 6.9.1 to write this article.
  4. Install Yarn using the Yarn installation instructions.
  5. Run the following command to install Yeoman.
yarn global add yo

6. Run the following command to install JHipster.

 yarn global add generator-jhipster

Create a project

To create a project, open a terminal window and create a directory. For example, mdkdir blog. Navigate into the directory and run yo jhipster. You’ll be asked a number of questions about the type of application you want to create and what features you’d like to include. The screenshot below shows the choices I made to create a simple blog application with Angular.

Figure 1. Generating the application

If you’d like to create the same application I did, you can place the following .yo-rc.json file in an empty directory and run yo jhipster in it. You won’t be prompted to answer any questions because the answers are already in .yo-rc.json.

{
  "generator-jhipster": {
    "jhipsterVersion": "4.0.5",
    "baseName": "blog",
    "packageName": "org.jhipster",
    "packageFolder": "org/jhipster",
    "serverPort": "8080",
    "authenticationType": "jwt",
    "hibernateCache": "ehcache",
    "clusteredHttpSession": false,
    "websocket": false,
    "databaseType": "sql",
    "devDatabaseType": "h2Disk",
    "prodDatabaseType": "postgresql",
    "searchEngine": false,
    "messageBroker": false,
    "serviceDiscoveryType": false,
    "buildTool": "maven",
    "enableSocialSignIn": false,
    "jwtSecretKey": "a895eda190e4ddf6eba453aa725bb4da8a565dfc",
    "clientFramework": "angular2",
    "useSass": true,
    "clientPackageManager": "yarn",
    "applicationType": "monolith",
    "clientFramework": "angular2",
    "testFrameworks": [
      "gatling",
      "protractor"
    ],
    "jhiPrefix": "jhi",
    "enableTranslation": true,
    "nativeLanguage": "en",
    "languages": [
      "en",
      "es"
    ]
  }
}

The project creation process will take a couple minutes to run, depending on your internet connection speed. When it’s finished, you should see output like the following.

Figure 2. Generation success

Run /.mvnw to start the application and navigate to http://localhost:8080 in your favorite browser. The first thing you’ll notice is a dapper-looking fellow explaining how you can sign in or register.

Figure 3. Default homepage

Sign in with username admin and password admin and you’ll have access to navigate through the Administration section. This section offers nice looking UIs on top of some Spring Boot’s many monitoring and configuration features. It also allows you to administer users:

Figure 4. User management

It gives you insights into Application and JVM metrics:

Figure 5. Application metrics

And it allows you to see the Swagger docs associated with its API.

Figure 6. Swagger docs

You can run the following command (in a separate terminal window) to run the Protractor tests and confirm everything is working properly.

yarn run e2e

At this point, it’s a good idea to check your project into Git so you can easily see what changes are made going forward.

git init
git add .
git commit -m "Project created"

Generate entities

For each entity you want to create, you will need:

  • a database table;
  • a Liquibase change set;
  • a JPA entity class;
  • a Spring Data JpaRepository interface;
  • a Spring MVC RestController class;
  • an Angular model, state, component, dialog components, service; and
  • several HTML pages for each component.

In addition, you should have integration tests to verify that everything works and performance tests to verify that it runs fast. In an ideal world, you’d also have unit tests and integration tests for your Angular code.

The good news is JHipster can generate all of this code for you, including integration tests and performance tests. In addition, if you have entities with relationships, it will generate the necessary schema to support them (with foreign keys), and the TypeScript and HTML code to manage them. You can also set up validation to require certain fields as well as control their length.

JHipster supports several methods of code generation. The first uses its entity sub-generator. The entity sub-generator is a command-line tool that prompts you with questions which you answer. JDL-Studio is a browser-based tool for defining your domain model with JHipster Domain Language (JDL). Finally, JHipster-UML is an option for those that like UML. Supported UML editors include Modelio, UML Designer, GenMyModel and Visual Paradigm. I like the visual nature of JDL-Studio, so I’ll use it for this project.

Below is the entity diagram and JDL code needed to generate a simple blog with blogs, entries and tags.

Figure 7. Blog entity diagram

You can click on this URL, or copy/paste the contents of the file below to your hard drive if you’d like to follow along.

.jhipster-jdl.jh

entity Blog {
	name String required minlength(3),
	handle String required minlength(2)
}

entity Entry {
	title String required,
	content TextBlob required,
	date ZonedDateTime required
}

entity Tag {
	name String required minlength(2)
}

relationship ManyToOne {
	Blog{user(login)} to User
        Entry{blog(name)} to Blog
}

relationship ManyToOne {
	Entry{blog(name)} to Blog
}

relationship ManyToMany {
	Entry{tag(name)} to Tag{entry}
}

paginate Entry, Tag with infinite-scroll

Run the following command (in the blog directory) to import this file and generate entities, tests and a UI.

yo jhipster:import-jdl ~/Downloads/jhipster-jdl.jh

You’ll be prompted to overwrite src/main/resources/config/liquibase/master.xml.  Type a to overwrite this file, as well as others.

Restart the application with /.mvnw and run yarn start to view the UI for the generated entities. Create a couple blogs for the existing admin and user users, as well as a few blog entries.

Figure 8. Blogs

Figure 9. Entries

From these screenshots, you can see that users can see each other’s data, and modify it.

Check your generated entities into Git.

     git init
     git add .
     git commit -m "Entities generated"

Add business logic

TIP: To configure an IDE with your JHipster project, see Configuring your IDE. Instructions exist for Eclipse, IntelliJ IDEA, Visual Studio Code, and NetBeans.

To add more security around blogs and entries, open BlogResource.java and find the getAllBlogs()method. Change the following line:

src/main/java/org/jhipster/web/rest/BlogResource.java

List<Blog> blogs = blogRepository.findAll();

To:

src/main/java/org/jhipster/web/rest/BlogResource.java

List<Blog> blogs = blogRepository.findByUserIsCurrentUser();

The findByUserIsCurrentUser() method is generated by JHipster in the BlogRespository class and allows limiting results by the current user.

src/main/java/org/jhipster/repository/BlogRepository.java

public interface BlogRepository extends JpaRepository<Blog,Long> {

    @Query("select blog from Blog blog where blog.user.login = ?#{principal.username}")
    List<Blog> findByUserIsCurrentUser();

}

After making this change, re-compiling BlogResource should trigger a restart of the application thanks to Spring Boot’s Developer tools. If you navigate to http://localhost:8080/blogs, you should only see the blog for the current user.

Figure 10. Admin’s blog

To add this same logic for entries, open EntryResource.java and find the getAllEntries() method. Change the following line:

src/main/java/org/jhipster/web/rest/EntryResource.java

Page<Entry> page = entryRepository.findAll(pageable);

To:

src/main/java/org/jhipster/web/rest/EntryResource.java

Page<Entry> page = entryRepository.findByBlogUserLoginOrderByDateDesc(SecurityUtils.getCurrentUserLogin(), pageable);

Using your IDE, create this method in the EntryRepository class. It should look as follows:

src/main/java/org/jhipster/repository/EntryRepository.java

Page<Entry> findByBlogUserLoginOrderByDateDesc(String currentUserLogin, Pageable pageable); 

Recompile both changed classes and verify that the user user only sees the entries you created for them.

Figure 11. User’s entries

After making these changes, commit them to Git.

git add .
git commit -m "Add business logic"

You might notice that this application doesn’t look like a blog and it doesn’t allow HTML in the content field.

Make UI enhancements

When doing UI development on a JHipster-generated application, it’s nice to see your changes as soon as you save a file. JHipster 4 uses Browsersync and webpack to power this feature. To enable it, run the following command in the blog directory.

yarn start

In this section, you’ll change the following:

  1. Change the rendered content field to display HTML
  2. Change the list of entries to look like a blog

Allow HTML

If you enter HTML in the content field of a blog entry, you’ll notice it’s escaped on the list screen.

Figure 12. Escaped HTML

To change this behavior, open entry.component.html and change the following line:

src/main/webapp/app/entities/entry/entry.component.html

 <td>{{entry.content}}</td>

To:

src/main/webapp/app/entities/entry/entry.component.html












<td [innerHTML]="entry.content"></td>












Figure 13. HTML in entries

After making this change, you’ll see that the HTML is no longer escaped.

Improve the layout

To make the list of entries look like a blog, replace <div class="table-responsive"> with HTML so it uses a stacked layout in a single column.

src/main/webapp/app/entities/entry/entry.component.html

<div class="table-responsive" *ngIf="entries">
    <div infinite-scroll (scrolled)="loadPage(page + 1)" [infiniteScrollDisabled]="page >= links['last']" [infiniteScrollDistance]="0">
        <div *ngFor="let entry of entries; trackBy: trackId">
            <h2>{{entry.title}}</h2>
            <small>Posted on {{entry.date | date: 'short'}} by {{entry.blog.user.login}}</small>
            <div [innerHTML]="entry.content"></div>
            <div class="btn-group mb-2 mt-1">
                <button type="submit"
                        [routerLink]="['/', { outlets: { popup: 'entry/'+ entry.id + '/edit'} }]"
                        replaceUrl="true"
                        class="btn btn-primary btn-sm">
                    <span class="fa fa-pencil"></span>
                    <span class="hidden-md-down" jhiTranslate="entity.action.edit">Edit</span>
                </button>
                <button type="submit"
                        [routerLink]="['/', { outlets: { popup: 'entry/'+ entry.id + '/delete'} }]"
                        replaceUrl="true"
                        class="btn btn-danger btn-sm">
                    <span class="fa fa-remove"></span>
                    <span class="hidden-md-down" jhiTranslate="entity.action.delete">Delete</span>
                </button>
            </div>
        </div>
    </div>
</div>

Now it looks more like a regular blog!

Figure 14. Blog entries

Commit all your changes to Git.

    git add .
    git commit -m "UI enhancements"

Deploy to the Cloud

A JHipster application can be deployed anywhere a Spring Boot application can be deployed.

JHipster ships with support for deploying to Cloud Foundry, Heroku, Kubernetes, AWS, and AWS with Boxfuse. I’m using Heroku in this example because it doesn’t cost me anything to host it.

When you prepare a JHipster application for production, it’s recommended to use the pre-configured “production” profile. With Maven, you can package your application by specifying the prod profile when building.

mvn -Pprod package

The production profile is used to build an optimized JavaScript client. You can invoke this using webpack by running yarn run webpack:prod. The production profile also configures gzip compression with a servlet filter, cache headers, and monitoring via Metrics. If you have a Graphite server configured in your application-prod.yaml file, your application will automatically send metrics data to it.

When you run this command, you’ll likely get a test failure.

Results :

Tests in error:
  BlogResourceIntTest.getAllBlogs:171 » NestedServlet Request processing failed;...

Tests run: 62, Failures: 0, Errors: 1, Skipped: 0

The reason this happens is shown in a stack trace in your terminal

getAllBlogs(org.jhipster.web.rest.BlogResourceIntTest)  Time elapsed: 0.041 sec  <<< ERROR!
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is
org.springframework.dao.InvalidDataAccessApiUsageException: Authentication object cannot be null;
nested exception is java.lang.IllegalArgumentException: Authentication object cannot be null

To fix this, you can use Spring Security Test’s @WithMockUser. Open BlogResourceIntTest.java and inject UserRepository as a dependency.

src/test/java/org/jhipster/web/rest/BlogResourceIntTest.java

@Autowired
private UserRepository userRepository;

Change the createEntity() method so it’s not static and uses the userRepository to set a user on the blog entity.

public Blog createEntity(EntityManager em) {
    Blog blog = new Blog()
            .name(DEFAULT_NAME)
            .handle(DEFAULT_HANDLE)
            .user(userRepository.findOneByLogin("user").get());
    return blog;
}

Add @WithMockUser to the getAllBlogs() method.

@Test
@Transactional
@WithMockUser
public void getAllBlogs() throws Exception {

After fixing this test, you should be able to run mvn -Pprod package without any failures.

To deploy this application to Heroku, I logged in to my Heroku account using heroku login from the command line. I already had the Heroku CLI installed.

$ heroku login
Enter your Heroku credentials.
Email: matt@raibledesigns.com
Password (typing will be hidden):
Logged in as matt@raibledesigns.com

I ran yo jhipster:heroku as recommended in the Deploying to Heroku documentation. I used the name “jhipster4-demo” for my application when prompted.

$ yo jhipster:heroku
Heroku configuration is starting
? Name to deploy as: jhipster4-demo
? On which region do you want to deploy ? us

Using existing Git repository

Installing Heroku CLI deployment plugin

Creating Heroku application and setting up node environment
heroku create jhipster-4-demo
https://jhipster-4-demo.herokuapp.com/ | https://git.heroku.com/jhipster-4-demo.git

Provisioning addons
Created heroku-postgresql --as DATABASE

Creating Heroku deployment files
   create src/main/resources/config/bootstrap-heroku.yml
   create src/main/resources/config/application-heroku.yml
   create Procfile

Building application
...
remote:        https://jhipster-4-demo.herokuapp.com/ deployed to Heroku
remote:
-----> Done

Your app should now be live. To view it run
	heroku open
And you can view the logs with this command
	heroku logs --tail
After application modification, redeploy it with
	yo jhipster:heroku

I ran heroku open, logged as admin and was pleased to see it worked!

Figure 15. JHipster 4 demo on Heroku

To save your changes for Heroku, commit your changes to Git.

git add .
git commit -m "Deploy to Heroku"

Learn more

I hope you’ve enjoyed learning how JHipster can help you develop hip web applications! It’s a nifty project, with an easy-to-use entity generator, a pretty UI and many Spring Boot best-practice patterns. The project team follows five simple policies, paraphrased here:

  1. The development team votes on policies.
  2. JHipster uses technologies with their default configurations as much as possible.
  3. Only add options when there is sufficient added value in the generated code.
  4. For the Java code, follow the default IntelliJ IDEA formatting and coding guidelines.
  5. Use strict versions for third-party libraries.

These policies help the project maintain its sharp edge and streamline its development process. If you have features you’d like to add or if you’d like to refine existing features, you can watch the project on GitHub and help with its development and support. We’re always looking for help!

Now that you’ve learned how to use Angular, Bootstrap 4, and Spring Boot with JHipster, go forth and develop great applications!

Source code

The source code for this project is available on GitHub at https://github.com/mraible/jhipster4-demo

eclipseorb_color

This post was originally published in the January 2017 issue of the Eclipse Newsletter: Exploring New Technology

For more information and articles check out the Eclipse Newsletter.

Author

Matt Raible

Matt Raible is a web developer and Java Champion. He loves to architect and build slick-looking UIs using CSS and JavaScript. When he’s not evangelizing Okta and open source, he likes to ski with his family, drive his VWs and enjoy craft beer. He blogs on his personal blog, and you can find him on Twitter @mraible. He is a developer on the JHipster team and authored the JHipster Mini-Book for InfoQ.


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