#2036 - Template variables of types requiring order are now inserted at the right place.

Support added for path segments, path style parameter and request parameters.

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

@@ -554,6 +554,10 @@ public final class TemplateVariable implements Serializable, UriTemplate.Expanda
 			return this.equals(type) || COMBINABLE_TYPES.contains(this) && COMBINABLE_TYPES.contains(type);
 		}
 
+		int findIndexWithin(String template) {
+			return template.indexOf(key);
+		}
+
 		/**
 		 * Returns the {@link VariableType} for the given variable key.
 		 *

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

@@ -15,6 +15,8 @@
  */
 package org.springframework.hateoas;
 
+import static org.springframework.hateoas.TemplateVariable.VariableType.*;
+
 import java.io.Serializable;
 import java.net.URI;
 import java.nio.charset.StandardCharsets;
@@ -28,6 +30,7 @@ import java.util.Map.Entry;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.springframework.hateoas.TemplateVariable.VariableType;
 import org.springframework.lang.Nullable;
@@ -35,7 +38,6 @@ import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
-import org.springframework.web.util.UriBuilderFactory;
 import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;
 import org.springframework.web.util.UriUtils;
@@ -178,6 +180,7 @@ public class UriTemplate implements Iterable<TemplateVariable>, Serializable {
 		List<TemplateVariable> result = new ArrayList<>();
 
 		for (TemplateVariable variable : variables) {
+
 			boolean isRequestParam = variable.isRequestParameterVariable();
 			boolean alreadyPresent = parameters.containsKey(variable.getName());
 
@@ -215,7 +218,7 @@ public class UriTemplate implements Iterable<TemplateVariable>, Serializable {
 				group = existing.merge(group);
 				newOriginal = newOriginal.replace(existing.asString(), group.asString());
 			} else {
-				newOriginal = newOriginal.concat(group.asString());
+				newOriginal = group.insertInto(newOriginal);
 			}
 
 			groups = groups.addOrAugment(group);
@@ -470,6 +473,28 @@ public class UriTemplate implements Iterable<TemplateVariable>, Serializable {
 			return this.type.canBeCombinedWith(type);
 		}
 
+		/**
+		 * Inserts the current {@link ExpandGroup} into the given URI template.
+		 *
+		 * @param template must not be {@literal null} or empty.
+		 * @return will never be {@literal null}.
+		 */
+		String insertInto(String template) {
+
+			var followingTypes = switch (type) {
+				case PATH_SEGMENT -> Stream.of(PATH_STYLE_PARAMETER, REQUEST_PARAM, FRAGMENT);
+				case PATH_STYLE_PARAMETER -> Stream.of(REQUEST_PARAM, FRAGMENT);
+				case REQUEST_PARAM, REQUEST_PARAM_CONTINUED -> Stream.of(FRAGMENT);
+				default -> Stream.<VariableType> empty();
+			};
+
+			return followingTypes.map(it -> it.findIndexWithin(template))
+					.filter(it -> it != -1)
+					.findFirst()
+					.map(it -> template.substring(0, it) + toString() + template.substring(it))
+					.orElseGet(() -> template.concat(toString()));
+		}
+
 		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.hateoas.UriTemplate.Expandable#asString()

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

@@ -45,7 +45,7 @@ class TemplateVariablesUnitTest {
 	@Test
 	void rendersSingleVariableCorrectly() {
 
-		TemplateVariables variables = new TemplateVariables(new TemplateVariable("foo", SEGMENT));
+		TemplateVariables variables = new TemplateVariables(new TemplateVariable("foo", PATH_SEGMENT));
 		assertThat(variables.toString()).isEqualTo("{/foo}");
 	}
 
@@ -69,7 +69,7 @@ class TemplateVariablesUnitTest {
 	@Test
 	void combinesMultipleVariablesOfTheDifferentType() {
 
-		TemplateVariable first = new TemplateVariable("foo", SEGMENT);
+		TemplateVariable first = new TemplateVariable("foo", PATH_SEGMENT);
 		TemplateVariable second = new TemplateVariable("bar", REQUEST_PARAM);
 
 		TemplateVariables variables = new TemplateVariables(first, second);
@@ -83,7 +83,7 @@ class TemplateVariablesUnitTest {
 	@Test
 	void concatsVariables() {
 
-		TemplateVariables variables = new TemplateVariables(new TemplateVariable("foo", SEGMENT));
+		TemplateVariables variables = new TemplateVariables(new TemplateVariable("foo", PATH_SEGMENT));
 		variables = variables.concat(new TemplateVariable("bar", REQUEST_PARAM));
 
 		assertThat(variables.toString()).isEqualTo("{/foo}{?bar}");
@@ -179,7 +179,7 @@ class TemplateVariablesUnitTest {
 	void variableRejectsEmptyName() {
 
 		assertThatIllegalArgumentException().isThrownBy(() -> {
-			new TemplateVariable("", PATH_VARIABLE);
+			new TemplateVariable("", SIMPLE);
 		});
 	}
 
@@ -190,7 +190,7 @@ class TemplateVariablesUnitTest {
 	void variableRejectsNullName() {
 
 		assertThatIllegalArgumentException().isThrownBy(() -> {
-			new TemplateVariable(null, PATH_VARIABLE);
+			new TemplateVariable(null, SIMPLE);
 		});
 	}
 
@@ -212,7 +212,7 @@ class TemplateVariablesUnitTest {
 	void variableRejectsNullDescription() {
 
 		assertThatIllegalArgumentException().isThrownBy(() -> {
-			new TemplateVariable("foo", PATH_VARIABLE, null, Cardinality.SINGULAR);
+			new TemplateVariable("foo", SIMPLE, null, Cardinality.SINGULAR);
 		});
 	}
 
@@ -220,7 +220,7 @@ class TemplateVariablesUnitTest {
 	void variableRejectsNullCardinality() {
 
 		assertThatIllegalArgumentException().isThrownBy(() -> {
-			new TemplateVariable("foo", PATH_VARIABLE, "description", null);
+			new TemplateVariable("foo", SIMPLE, "description", null);
 		});
 	}
 }

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

@@ -387,6 +387,21 @@ class UriTemplateUnitTest {
 		assertThat(UriTemplate.of("/path/{foo.bar}").getVariableNames()).contains("foo.bar");
 	}
 
+	@Test // #2036
+	void addsPathSegmentAtTheRightPositionWithinTheUri() {
+
+		var template = UriTemplate.of("/api?foo=bar#baz");
+
+		assertThat(template.with("p", VariableType.REQUEST_PARAM).toString())
+				.isEqualTo("/api?foo=bar{&p}#baz");
+
+		assertThat(template.with("p", VariableType.PATH_SEGMENT).toString())
+				.isEqualTo("/api{/p}?foo=bar#baz");
+
+		assertThat(template.with("p", VariableType.PATH_STYLE_PARAMETER).toString())
+				.isEqualTo("/api{;p}?foo=bar#baz");
+	}
+
 	private static void assertVariables(UriTemplate template, TemplateVariable... variables) {
 		assertVariables(template, Arrays.asList(variables));
 	}