#1504 - Add RepresentationModel.mapLinkIf(…).

Author: odrotbohm

src/main/java/org/springframework/hateoas/RepresentationModel.java

@@ -309,6 +309,25 @@ public List<Link> getLinks(LinkRelation relation) {
 	 * @since 1.3
 	 */
 	public T mapLink(LinkRelation relation, Function<Link, Link> mapper) {
+		return mapLinkIf(true, relation, mapper);
+	}
+
+	/**
+	 * Replaces the link(s) with the given {@link LinkRelation} with the mapper applied to each of the links if the given
+	 * condition is true.
+	 *
+	 * @param condition the condition that needs to be {@literal true} to apply the mapping.
+	 * @param relation the {@link LinkRelation} to select the source link(s), must not be {@literal null}.
+	 * @param mapper the {@link Function} to apply to the current link, must not be {@literal null}.
+	 * @return will never be {@literal null}.
+	 * @since 1.3
+	 */
+	@SuppressWarnings("unchecked")
+	public T mapLinkIf(boolean condition, LinkRelation relation, Function<Link, Link> mapper) {
+
+		if (!condition) {
+			return (T) this;
+		}
 
 		getLinks(relation).forEach(it -> {
 

src/test/java/org/springframework/hateoas/RepresentationModelUnitTest.java

@@ -204,4 +204,19 @@ void replacesLink() {
 
 		assertThat(model.getRequiredLink(IanaLinkRelations.SELF).getHref()).isEqualTo("/bar");
 	}
+
+	@Test // #1504
+	void mapsLinkConditionally() {
+
+		RepresentationModel<?> model = new RepresentationModel<>();
+		model.add(Link.of("/foo", IanaLinkRelations.SELF));
+
+		model.mapLinkIf(false, IanaLinkRelations.SELF, it -> Link.of("/bar"));
+
+		assertThat(model.getRequiredLink(IanaLinkRelations.SELF).getHref()).isEqualTo("/foo");
+
+		model.mapLinkIf(true, IanaLinkRelations.SELF, it -> Link.of("/bar"));
+
+		assertThat(model.getRequiredLink(IanaLinkRelations.SELF).getHref()).isEqualTo("/bar");
+	}
 }