Add support for fully-qualified links

- also make the linkrel configurable
Fixes #148

spring-content-autoconfigure/src/main/java/internal/org/springframework/content/rest/boot/autoconfigure/ContentRestAutoConfiguration.java

@@ -22,6 +22,7 @@ public class ContentRestAutoConfiguration {
 	public static class ContentRestProperties {
 
 		private URI baseUri;
+		private boolean fullyQualifiedLinks = false;
 
 		public URI getBaseUri() {
 			return baseUri;
@@ -30,7 +31,15 @@ public URI getBaseUri() {
 		public void setBaseUri(URI baseUri) {
 			this.baseUri = baseUri;
 		}
-	}
+
+		public boolean fullyQualifiedLinks() {
+			return this.fullyQualifiedLinks;
+		}
+
+		public void setFullyQualifiedLinks(boolean fullyQualifiedLinks) {
+			this.fullyQualifiedLinks = fullyQualifiedLinks;
+		}
+    }
 
 	@Bean
 	public SpringBootContentRestConfigurer springBootContentRestConfigurer() {

spring-content-autoconfigure/src/main/java/internal/org/springframework/content/rest/boot/autoconfigure/SpringBootContentRestConfigurer.java

@@ -23,9 +23,14 @@ public SpringBootContentRestConfigurer(ContentRestProperties properties) {
     @Override
     public void configure(RestConfiguration config) {
 
-        if (properties == null || properties.getBaseUri() == null)
+        if (properties == null) {
             return;
+        }
 
-        config.setBaseUri(properties.getBaseUri());
+        if (properties.getBaseUri() != null) {
+            config.setBaseUri(properties.getBaseUri());
+        }
+
+        config.setFullyQualifiedLinks(properties.fullyQualifiedLinks());
     }
 }

spring-content-autoconfigure/src/test/java/org/springframework/content/rest/boot/ContentRestAutoConfigurationTest.java

@@ -50,21 +50,22 @@ public class ContentRestAutoConfigurationTest {
 				});
 			});
 
-			Context("given an environment specifying a base uri", () -> {
+			Context("given an environment specifying rest properties", () -> {
 				BeforeEach(() -> {
 					System.setProperty("spring.content.rest.base-uri", "/contentApi");
+					System.setProperty("spring.content.rest.content-links", "false");
 				});
 				AfterEach(() -> {
 					System.clearProperty("spring.content.rest.base-uri");
 				});
-				It("should have a filesystem properties bean with the correct root set", () -> {
+				It("should have a filesystem properties bean with the correct properties set", () -> {
 					AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
 					context.register(TestConfig.class);
 					context.setServletContext(new MockServletContext());
 					context.refresh();
 
-					assertThat(context.getBean(ContentRestAutoConfiguration.ContentRestProperties.class).getBaseUri(),
-								is(URI.create("/contentApi")));
+					assertThat(context.getBean(ContentRestAutoConfiguration.ContentRestProperties.class).getBaseUri(), is(URI.create("/contentApi")));
+					assertThat(context.getBean(ContentRestAutoConfiguration.ContentRestProperties.class).fullyQualifiedLinks(), is(false));
 
 					assertThat(context.getBean(SpringBootContentRestConfigurer.class), is(not(nullValue())));
 

spring-content-autoconfigure/src/test/java/org/springframework/content/rest/boot/SpringBootContentRestConfigurerTest.java

@@ -14,6 +14,7 @@
 import static com.github.paulcwarren.ginkgo4j.Ginkgo4jDSL.Describe;
 import static com.github.paulcwarren.ginkgo4j.Ginkgo4jDSL.It;
 import static com.github.paulcwarren.ginkgo4j.Ginkgo4jDSL.JustBeforeEach;
+import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.anyObject;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
@@ -56,6 +57,17 @@ public class SpringBootContentRestConfigurerTest {
                     });
                 });
 
+                Context("given a fullyQualifiedLinks property setting", () -> {
+
+                    BeforeEach(() -> {
+                        properties.setFullyQualifiedLinks(true);
+                    });
+
+                    It("should set the property on the RestConfiguration", () -> {
+                        verify(restConfig).setFullyQualifiedLinks(eq(true));
+                    });
+                });
+
                 Context("given a null base uri property", () -> {
 
                     It("should not set the property on the RestConfiguration", () -> {
@@ -71,6 +83,7 @@ public class SpringBootContentRestConfigurerTest {
 
                     It("should not set the property on the RestConfiguration", () -> {
                         verify(restConfig, never()).setBaseUri(anyObject());
+                        verify(restConfig, never()).setFullyQualifiedLinks(anyBoolean());
                     });
                 });
             });

spring-content-rest/src/main/asciidoc/rest-baseuri.adoc

@@ -32,3 +32,4 @@ class CustomContentRestMvcConfiguration {
 }
 ----
 ====
+

spring-content-rest/src/main/asciidoc/rest-fullyqualifiedlinks.adoc

@@ -0,0 +1,104 @@
+== Fully Qualified Links
+By default, and where possible, Spring Content REST exports Spring Resources to shortened link URIs.  These will often
+match the Spring Data Rest Entity URI.
+
+Given the following example:
+
+====
+[source, java]
+----
+  @Entity
+  public class Dvd {
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    @ContentId
+    private UUID contentId;
+
+    @ContentLength
+    private Long contentLength;
+
+    @MimeType
+    private String mimeType;
+
+    // getters and setters
+  }
+
+  public interface DvdRepository extends CrudRepository<Dvd, Long> {}
+
+  public interface DvdStore extends ContentStore<Dvd, UUID> {}
+----
+====
+
+As there is only a single associated Spring Resource, Spring Content REST will generate the following URI:
+
+====
+[source, java]
+----
+  "_links" : {
+    "self" : {
+      ...
+    },
+    "dvd" : {
+      ...
+    },
+    "dvds" : {
+      "href" : "http://localhost:8080/dvds/1"
+    }
+  }
+----
+====
+
+To generate fully qualified link URIs set the following property:
+
+====
+[source, java]
+----
+spring.content.rest.fullyQualifiedLinks=true
+----
+====
+
+Or if you are not using Spring Boot, you can do the following:
+
+====
+[source, java]
+----
+@Configuration
+class CustomContentRestMvcConfiguration {
+
+  @Bean
+  public ContentRestConfigurer contentRestConfigurer() {
+
+    return new ContentRestConfigurer() {
+
+      @Override
+      public void configure(RestConfiguration config) {
+        config.setFullyQualifiedLinks(true);
+      }
+    };
+  }
+}
+----
+====
+
+Spring Content REST will now generate links as follows:
+
+====
+[source, java]
+----
+  "_links" : {
+    "self" : {
+      ...
+    },
+    "dvd" : {
+      ...
+    },
+    "content" : {
+      "href" : "http://localhost:8080/dvds/1/content"
+    }
+  }
+----
+====
+
+where `content` is the extracted property name taken from the field `contentId`.

spring-content-rest/src/main/asciidoc/rest-index.adoc

@@ -36,6 +36,8 @@ include::{spring-versions-jpa-docs}/jpaversions-rest.adoc[leveloffset=+1]
 include::rest-cors.adoc[leveloffset=+1]
 
 include::rest-baseuri.adoc[leveloffset=+1]
+include::rest-linkrel.adoc[leveloffset=+1]
+include::rest-fullyqualifiedlinks.adoc[leveloffset=+1]
 //[[appendix]]
 //= Appendix
 

spring-content-rest/src/main/asciidoc/rest-linkrel.adoc

@@ -0,0 +1,83 @@
+== Changing the link relation
+
+For each exported Spring Resource, Spring Content REST will generate a suitable linkrel.
+
+However, it can sometimes be useful to control this yourself.
+
+Given the following example:
+
+====
+[source, java]
+----
+  @Entity
+  public class Dvd {
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    @ContentId
+    private UUID contentId;
+
+    @ContentLength
+    private Long contentLength;
+
+    @MimeType
+    private String mimeType;
+
+    // getters and setters
+  }
+
+  public interface DvdRepository extends CrudRepository<Dvd, Long> {}
+
+  public interface DvdStore extends ContentStore<Dvd, UUID> {}
+----
+====
+
+Spring Content REST will export the Spring Resource to the following linkrel:
+
+====
+[source, java]
+----
+  "_links" : {
+    "self" : {
+      ...
+    },
+    "dvd" : {
+      ...
+    },
+    "dvds" : {
+      "href" : "http://localhost:8080/dvds/1"
+    }
+  }
+----
+====
+
+Specifying a `linkRel` on the StoreRestResource, as follows:
+
+====
+[source, java]
+----
+  @StoreRestResource(linkRel="content")
+  public interface DvdStore extends ContentStore<Dvd, UUID> {}
+----
+====
+
+will result in the following linkrel instead:
+
+====
+[source, java]
+----
+ "_links" : {
+    "self" : {
+      ...
+    },
+    "dvd" : {
+      ...
+    },
+    "content" : {
+      "href" : "http://localhost:8080/dvds/1"
+    }
+  }
+----
+====
+