#1696 - Re-instantiate conversion for request parameter template variables.

When adding a request parameter template variable and the URI part of the template already contains a request parameter we now automatically turn the variable type into request parameter continuation. That apparently got lost in the move to level 4 URI templates in #1583.

Author: odrotbohm

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

@@ -32,6 +32,7 @@
 import org.springframework.hateoas.TemplateVariable.VariableType;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
 import org.springframework.web.util.UriBuilderFactory;
 import org.springframework.web.util.UriComponents;
@@ -177,8 +178,9 @@ public UriTemplate with(TemplateVariables variables) {
 
 		for (TemplateVariable variable : variables) {
 
+			MultiValueMap<String, String> parameters = components.getQueryParams();
 			boolean isRequestParam = variable.isRequestParameterVariable();
-			boolean alreadyPresent = components.getQueryParams().containsKey(variable.getName());
+			boolean alreadyPresent = parameters.containsKey(variable.getName());
 
 			if (isRequestParam && alreadyPresent) {
 				continue;
@@ -188,6 +190,11 @@ public UriTemplate with(TemplateVariables variables) {
 				continue;
 			}
 
+			// Use request parameter continuation if base contains parameters already
+			if (!parameters.isEmpty() && variable.getType().equals(VariableType.REQUEST_PARAM)) {
+				variable = variable.withType(VariableType.REQUEST_PARAM_CONTINUED);
+			}
+
 			ExpandGroup existing = groups.findLastExpandGroupOfType(variable.getType());
 			ExpandGroup group = new ExpandGroup(Collections.singletonList(variable));
 

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

@@ -366,6 +366,15 @@ void expandsCompositePaths() {
 		assertThat(uri).isEqualTo(URI.create("/foo/first/second"));
 	}
 
+	@Test // #1696
+	void adaptsRequestParamVariableToContinuationIfBaseUriContainsParameter() {
+
+		UriTemplate template = UriTemplate.of("/path/{bar}/foo.zip?type=foo")
+				.with(new TemplateVariable("foobar", VariableType.REQUEST_PARAM));
+
+		assertThat(template.toString()).isEqualTo("/path/{bar}/foo.zip?type=foo{&foobar}");
+	}
+
 	private static void assertVariables(UriTemplate template, TemplateVariable... variables) {
 		assertVariables(template, Arrays.asList(variables));
 	}