BAEL-2981: Added code samples for Handlebars.java

libraries-2/pom.xml

@@ -81,13 +81,17 @@
 			<version>3.14.2</version>
 			<scope>test</scope>
 		</dependency>
-
         <dependency>
             <groupId>edu.uci.ics</groupId>
             <artifactId>crawler4j</artifactId>
             <version>${crawler4j.version}</version>
         </dependency>
-          
+        <!-- HandleBars -->
+        <dependency>
+            <groupId>com.github.jknack</groupId>
+            <artifactId>handlebars</artifactId>
+            <version>4.1.2</version>
+        </dependency>
 	</dependencies>
 
 	<properties>

libraries-2/src/test/java/com/baeldung/handlebars/BasicUsageUnitTest.java

@@ -0,0 +1,104 @@
+package com.baeldung.handlebars;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.github.jknack.handlebars.Handlebars;
+import com.github.jknack.handlebars.Template;
+import com.github.jknack.handlebars.io.ClassPathTemplateLoader;
+import com.github.jknack.handlebars.io.TemplateLoader;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.Test;
+
+public class BasicUsageUnitTest {
+
+    @Test
+    public void whenThereIsNoTemplateFile_ThenCompilesInline() throws IOException {
+        Handlebars handlebars = new Handlebars();
+        Template template = handlebars.compileInline("Hi {{this}}!");
+
+        String templateString = template.apply("Baeldung");
+
+        assertThat(templateString).isEqualTo("Hi Baeldung!");
+    }
+
+    @Test
+    public void whenParameterMapIsSupplied_thenDisplays() throws IOException {
+        Handlebars handlebars = new Handlebars();
+        Template template = handlebars.compileInline("Hi {{name}}!");
+
+        Map<String, String> parameterMap = new HashMap<>();
+        parameterMap.put("name", "Baeldung");
+        String templateString = template.apply(parameterMap);
+
+        assertThat(templateString).isEqualTo("Hi Baeldung!");
+    }
+
+    @Test
+    public void whenParameterObjectIsSupplied_ThenDisplays() throws IOException {
+        Handlebars handlebars = new Handlebars();
+        Template template = handlebars.compileInline("Hi {{name}}!");
+
+        Person person = new Person();
+        person.setName("Baeldung");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("Hi Baeldung!");
+    }
+
+    @Test
+    public void whenMultipleParametersAreSupplied_ThenDisplays() throws IOException {
+        Handlebars handlebars = new Handlebars();
+        Template template = handlebars.compileInline("Hi {{name}}! This is {{topic}}.");
+
+        Map<String, String> parameterMap = new HashMap<>();
+        parameterMap.put("name", "Baeldung");
+        parameterMap.put("topic", "Handlebars");
+        String templateString = template.apply(parameterMap);
+
+        assertThat(templateString).isEqualTo("Hi Baeldung! This is Handlebars.");
+    }
+
+    @Test
+    public void whenNoLoaderIsGiven_ThenSearchesClasspath() throws IOException {
+        Handlebars handlebars = new Handlebars();
+        Template template = handlebars.compile("greeting");
+
+        Person person = getPerson("Baeldung");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("Hi Baeldung!");
+    }
+
+    @Test
+    public void whenClasspathTemplateLoaderIsGiven_ThenSearchesClasspathWithPrefixSuffix() throws IOException {
+        TemplateLoader loader = new ClassPathTemplateLoader("/handlebars", ".html");
+        Handlebars handlebars = new Handlebars(loader);
+        Template template = handlebars.compile("greeting");
+
+        Person person = getPerson("Baeldung");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("Hi Baeldung!");
+    }
+
+    @Test
+    public void whenMultipleLoadersAreGiven_ThenSearchesSequentially() throws IOException {
+        TemplateLoader firstLoader = new ClassPathTemplateLoader("/handlebars", ".html");
+        TemplateLoader secondLoader = new ClassPathTemplateLoader("/templates", ".html");
+        Handlebars handlebars = new Handlebars().with(firstLoader, secondLoader);
+        Template template = handlebars.compile("greeting");
+
+        Person person = getPerson("Baeldung");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("Hi Baeldung!");
+    }
+
+    private Person getPerson(String name) {
+        Person person = new Person();
+        person.setName(name);
+        return person;
+    }
+}

libraries-2/src/test/java/com/baeldung/handlebars/BuiltinHelperUnitTest.java

@@ -0,0 +1,101 @@
+package com.baeldung.handlebars;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.github.jknack.handlebars.Handlebars;
+import com.github.jknack.handlebars.Template;
+import com.github.jknack.handlebars.io.ClassPathTemplateLoader;
+import com.github.jknack.handlebars.io.TemplateLoader;
+import java.io.IOException;
+import org.junit.Test;
+
+public class BuiltinHelperUnitTest {
+
+    private TemplateLoader templateLoader = new ClassPathTemplateLoader("/handlebars", ".html");
+
+    @Test
+    public void whenUsedWith_ThenContextChanges() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        Template template = handlebars.compile("with");
+
+        Person person = getPerson("Baeldung");
+        person.getAddress().setStreet("World");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("\n<h4>I live in World</h4>\n");
+    }
+
+    @Test
+    public void whenUsedWithMustacheStyle_ThenContextChanges() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        Template template = handlebars.compile("with_mustache");
+
+        Person person = getPerson("Baeldung");
+        person.getAddress().setStreet("World");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("\n<h4>I live in World</h4>\n");
+    }
+
+    @Test
+    public void whenUsedEach_ThenIterates() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        Template template = handlebars.compile("each");
+
+        Person person = getPerson("Baeldung");
+        Person friend1 = getPerson("Java");
+        Person friend2 = getPerson("Spring");
+        person.getFriends().add(friend1);
+        person.getFriends().add(friend2);
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("\n<span>Java is my friend.</span>\n"
+                                               + "\n<span>Spring is my friend.</span>\n");
+    }
+
+    @Test
+    public void whenUsedEachMustacheStyle_ThenIterates() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        Template template = handlebars.compile("each_mustache");
+
+        Person person = getPerson("Baeldung");
+        Person friend1 = getPerson("Java");
+        Person friend2 = getPerson("Spring");
+        person.getFriends().add(friend1);
+        person.getFriends().add(friend2);
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("\n<span>Java is my friend.</span>\n"
+                                               + "\n<span>Spring is my friend.</span>\n");
+    }
+
+    @Test
+    public void whenUsedIf_ThenPutsCondition() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        Template template = handlebars.compile("if");
+
+        Person person = getPerson("Baeldung");
+        person.setBusy(true);
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("\n<h4>Baeldung is busy.</h4>\n");
+    }
+
+    @Test
+    public void whenUsedIfMustacheStyle_ThenPutsCondition() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        Template template = handlebars.compile("if_mustache");
+
+        Person person = getPerson("Baeldung");
+        person.setBusy(true);
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("\n<h4>Baeldung is busy.</h4>\n");
+    }
+
+    private Person getPerson(String name) {
+        Person person = new Person();
+        person.setName(name);
+        return person;
+    }
+}

libraries-2/src/test/java/com/baeldung/handlebars/CustomHelperUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.handlebars;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.github.jknack.handlebars.Handlebars;
+import com.github.jknack.handlebars.Helper;
+import com.github.jknack.handlebars.Options;
+import com.github.jknack.handlebars.Template;
+import com.github.jknack.handlebars.io.ClassPathTemplateLoader;
+import com.github.jknack.handlebars.io.TemplateLoader;
+import java.io.IOException;
+import org.junit.Test;
+
+public class CustomHelperUnitTest {
+
+    private TemplateLoader templateLoader = new ClassPathTemplateLoader("/handlebars", ".html");
+
+    @Test
+    public void whenHelperIsCreated_ThenCanRegister() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        handlebars.registerHelper("person", new Helper<Person>() {
+            @Override
+            public Object apply(Person context, Options options) throws IOException {
+                String busyString = context.isBusy() ? "busy" : "available";
+                return context.getName() + " - " + busyString;
+            }
+        });
+        Template template = handlebars.compile("person");
+
+        Person person = getPerson("Baeldung");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("Baeldung - busy");
+    }
+
+    @Test
+    public void whenHelperSourceIsCreated_ThenCanRegister() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        handlebars.registerHelpers(new HelperSource());
+        Template template = handlebars.compile("person");
+
+        Person person = getPerson("Baeldung");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("Baeldung - busy");
+    }
+
+    private Person getPerson(String name) {
+        Person person = new Person();
+        person.setName(name);
+        person.setBusy(true);
+        return person;
+    }
+}

libraries-2/src/test/java/com/baeldung/handlebars/HelperSource.java

@@ -0,0 +1,9 @@
+package com.baeldung.handlebars;
+
+public class HelperSource {
+
+    public String person(Person context) {
+        String busyString = context.isBusy() ? "busy" : "available";
+        return context.getName() + " - " + busyString;
+    }
+}

libraries-2/src/test/java/com/baeldung/handlebars/Person.java

@@ -0,0 +1,58 @@
+package com.baeldung.handlebars;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Person {
+
+    private String name;
+    private boolean busy;
+    private Address address = new Address();
+    private List<Person> friends = new ArrayList<>();
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public boolean isBusy() {
+        return busy;
+    }
+
+    public void setBusy(boolean busy) {
+        this.busy = busy;
+    }
+
+    public Address getAddress() {
+        return address;
+    }
+
+    public void setAddress(Address address) {
+        this.address = address;
+    }
+
+    public List<Person> getFriends() {
+        return friends;
+    }
+
+    public void setFriends(List<Person> friends) {
+        this.friends = friends;
+    }
+
+    public static class Address {
+
+        private String street;
+
+        public String getStreet() {
+            return street;
+        }
+
+        public void setStreet(String street) {
+            this.street = street;
+        }
+    }
+
+}

libraries-2/src/test/java/com/baeldung/handlebars/ReusingTemplatesUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.handlebars;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.github.jknack.handlebars.Handlebars;
+import com.github.jknack.handlebars.Template;
+import com.github.jknack.handlebars.io.ClassPathTemplateLoader;
+import com.github.jknack.handlebars.io.TemplateLoader;
+import java.io.IOException;
+import org.junit.Test;
+
+public class ReusingTemplatesUnitTest {
+
+    private TemplateLoader templateLoader = new ClassPathTemplateLoader("/handlebars", ".html");
+
+    @Test
+    public void whenOtherTemplateIsReferenced_ThenCanReuse() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        Template template = handlebars.compile("page");
+
+        Person person = new Person();
+        person.setName("Baeldung");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("<h4>Hi Baeldung!</h4>\n<p>This is the page Baeldung</p>");
+    }
+
+    @Test
+    public void whenBlockIsDefined_ThenCanOverrideWithPartial() throws IOException {
+        Handlebars handlebars = new Handlebars(templateLoader);
+        Template template = handlebars.compile("simplemessage");
+
+        Person person = new Person();
+        person.setName("Baeldung");
+        String templateString = template.apply(person);
+
+        assertThat(templateString).isEqualTo("\n<html>\n"
+                                               + "<body>\n"
+                                               + "\n  This is the intro\n\n"
+                                               + "\n  Hi there!\n\n"
+                                               + "</body>\n"
+                                               + "</html>");
+    }
+}

libraries-2/src/test/resources/greeting.hbs

@@ -0,0 +1 @@
+Hi {{name}}!

libraries-2/src/test/resources/handlebars/each.html

@@ -0,0 +1,3 @@
+{{#each friends}}
+<span>{{name}} is my friend.</span>
+{{/each}}

libraries-2/src/test/resources/handlebars/each_mustache.html

@@ -0,0 +1,3 @@
+{{#each friends}}
+<span>{{name}} is my friend.</span>
+{{/each}}

libraries-2/src/test/resources/handlebars/greeting.html

@@ -0,0 +1 @@
+Hi {{name}}!

libraries-2/src/test/resources/handlebars/header.html

@@ -0,0 +1 @@
+<h4>Hi {{name}}!</h4>

libraries-2/src/test/resources/handlebars/if.html

@@ -0,0 +1,5 @@
+{{#if busy}}
+<h4>{{name}} is busy.</h4>
+{{else}}
+<h4>{{name}} is not busy.</h4>
+{{/if}}

libraries-2/src/test/resources/handlebars/if_mustache.html

@@ -0,0 +1,5 @@
+{{#if busy}}
+<h4>{{name}} is busy.</h4>
+{{^}}
+<h4>{{name}} is not busy.</h4>
+{{/if}}

libraries-2/src/test/resources/handlebars/messagebase.html

@@ -0,0 +1,9 @@
+<html>
+<body>
+{{#block "intro"}}
+  This is the intro
+{{/block}}
+{{#block "message"}}
+{{/block}}
+</body>
+</html>

libraries-2/src/test/resources/handlebars/page.html

@@ -0,0 +1,2 @@
+{{>header}}
+<p>This is the page {{name}}</p>

libraries-2/src/test/resources/handlebars/person.html

@@ -0,0 +1 @@
+{{#person this}}{{/person}}

libraries-2/src/test/resources/handlebars/simplemessage.html

@@ -0,0 +1,4 @@
+{{#partial "message" }}
+  Hi there!
+{{/partial}}
+{{> messagebase}}

libraries-2/src/test/resources/handlebars/with.html

@@ -0,0 +1,3 @@
+{{#with address}}
+<h4>I live in {{street}}</h4>
+{{/with}}

libraries-2/src/test/resources/handlebars/with_mustache.html

@@ -0,0 +1,3 @@
+{{#address}}
+<h4>I live in {{street}}</h4>
+{{/address}}