Dropwizard Views

Templates Supported

Dropwizard view currently supports the FreeMarker template and Mustache template. We must select one of the view templates to use Dropwizard views. 

The "dropwizard-view" dependency gets replaced with "dropwizard-views-mustache" or "dropwizard-views-freemarker", and dropwizard-view will then get included as a dependency. We will add the ViewBundle to our application's initialize method to enable views.

Dropwizard Freemarker Template

The FreeMarkerTM is a template engine. It's a Java library that uses templates and data to generate text output. FreeMarker Template Language (FTL), a simple and specialized language, is used to create templates. We can concentrate on how to present the data by using a template. We will be looking at the data to present outside of the template. It is a free template that we can easily use.

We can use the following code for freemarker dependency.

<!--- https://mvnrepository.com/artifact/io.dropwizard/dropwizard-views-freemarker --->
<dependency>
	<groupId>
		io.dropwizard
	</groupId>
	<artifactId>
		dropwizard-views-freemarker
	</artifactId>

	// The ${dropwizard.version} is to mention the current version of dropwizard.
	<version>
		${dropwizard.version}
	</version>
</dependency>

Dropwizard Mustache Template

The Mustache is a logic-less template used in dropwizard views. Mustache is ideal for HTML, configuration files, source code, etc. It uses values from a hash or object to expand tags in a template.

Since there are no if statements, else clauses, or for loops, we call it "logic less". There are only tags present. Some tags are replaced with a value, others with no value and others with a set of values.

Mustache template allows us to use pre-written text files containing placeholders that the system will fill in during run-time with values unique to a given request.

Template Errors

The templates use it to notify errors, such as invalid input. It helps the editor see the errors. It also helps other templates to catch errors and manage them. For example, suppose an error has occurred in a template (E.g., The template file is missing or there is an error while compiling the template). In that case, the user will receive an Internal Server Error-500 with a generic HTML message by default. Under the error mode, the precise error will get logged.

We will create an exception mapper that will help to override the default one by looking for ViewRenderException. The ViewRenderException will help to customize the behavior. If we cannot find mustache templates, we can return error 404 instead of an internal server error.

Caching

The templates get cached by default to improve the loading time. 

We will set the cache property in the view configuration. We keep it as false to disable it during development mode.

views:
	.mustache
	cache: false 

Custom Error Pages

You can use a custom error view to get HTML error pages that match the application. We will create a View with an ErrorMessage parameter in its constructor. Then we will connect it by registering an ErrorEntityWriter instance.

We can register another ErrorEntityWriter that handles ValidationErrorMessage objects to handle validation error messages.

Frequently Asked Questions

What is Dropwizard? 

Dropwizard is an open-source framework of Java. It is used for the fast development of high-performance RESTful web services. 

What is bootstrap in Dropwizard?

The bootstrap is a pre-start (temporary) application environment. It contains all of the components needed to bootstrap a Dropwizard command.

What is the Freemarker template in Drowizard?

The FreeMarkerTM is a template engine. It's a Java library that uses templates and data to generate text output.

What are the Dropwizard views?

The dropwizard views support the localized template files. It provides us with simple and quick views of HTML, which is done by using a freemarker or mustache.

Name the libraries gathered in Dropwizard.

Dropwizard gathers many popular libraries. These are Jersey, Jackson, Jetty, JUnit, Guava, etc. Furthermore, it uses its own library called Metrics.

Conclusion

In this article, we covered all about the Dropwizard views. The reader can carry out a thorough understanding of the topic by referring to the Official Documentation.

Take a look at similar topics and check out our related articles-

• Dropwizard JDBI3
• Dropwizard Forms
• Dropwizard Example
   

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