Query param route predicate - extension of QueryRoutePredicateFactory

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@@ -206,6 +206,7 @@ public StringToZonedDateTimeConverter stringToZonedDateTimeConverter() {
 	 * @deprecated in favour of
 	 * {@link org.springframework.cloud.gateway.support.config.KeyValueConverter}
 	 */
+	@Deprecated
 	@Bean
 	public org.springframework.cloud.gateway.support.KeyValueConverter deprecatedKeyValueConverter() {
 		return new org.springframework.cloud.gateway.support.KeyValueConverter();

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/handler/predicate/QueryRoutePredicateFactory.java

@@ -20,6 +20,7 @@
 import java.util.List;
 import java.util.function.Predicate;
 
+import jakarta.validation.constraints.AssertTrue;
 import jakarta.validation.constraints.NotEmpty;
 
 import org.springframework.util.StringUtils;
@@ -41,21 +42,26 @@ public class QueryRoutePredicateFactory extends AbstractRoutePredicateFactory<Qu
 	 */
 	public static final String REGEXP_KEY = "regexp";
 
+	/**
+	 * Predicate key.
+	 */
+	public static final String PREDICATE_KEY = "predicate";
+
 	public QueryRoutePredicateFactory() {
 		super(Config.class);
 	}
 
 	@Override
 	public List<String> shortcutFieldOrder() {
-		return Arrays.asList(PARAM_KEY, REGEXP_KEY);
+		return Arrays.asList(PARAM_KEY, REGEXP_KEY, PREDICATE_KEY);
 	}
 
 	@Override
 	public Predicate<ServerWebExchange> apply(Config config) {
 		return new GatewayPredicate() {
 			@Override
 			public boolean test(ServerWebExchange exchange) {
-				if (!StringUtils.hasText(config.regexp)) {
+				if (!StringUtils.hasText(config.regexp) && config.predicate == null) {
 					// check existence of header
 					return exchange.getRequest().getQueryParams().containsKey(config.param);
 				}
@@ -64,8 +70,13 @@ public boolean test(ServerWebExchange exchange) {
 				if (values == null) {
 					return false;
 				}
+
+				Predicate<String> predicate = config.predicate;
+				if (StringUtils.hasText(config.regexp)) {
+					predicate = value -> value.matches(config.regexp);
+				}
 				for (String value : values) {
-					if (value != null && value.matches(config.regexp)) {
+					if (value != null && predicate.test(value)) {
 						return true;
 					}
 				}
@@ -92,8 +103,10 @@ public static class Config {
 
 		private String regexp;
 
+		private Predicate<String> predicate;
+
 		public String getParam() {
-			return param;
+			return this.param;
 		}
 
 		public Config setParam(String param) {
@@ -102,14 +115,34 @@ public Config setParam(String param) {
 		}
 
 		public String getRegexp() {
-			return regexp;
+			return this.regexp;
 		}
 
 		public Config setRegexp(String regexp) {
 			this.regexp = regexp;
 			return this;
 		}
 
+		public Predicate<String> getPredicate() {
+			return this.predicate;
+		}
+
+		public Config setPredicate(Predicate<String> predicate) {
+			this.predicate = predicate;
+			return this;
+		}
+
+		/**
+		 * Enforces the validation done on predicate configuration: {@link #regexp} and
+		 * {@link #predicate} can't be both set at runtime.
+		 * @return <code>false</code> if {@link #regexp} and {@link #predicate} are both
+		 * set in this predicate factory configuration
+		 */
+		@AssertTrue
+		public boolean isValid() {
+			return !(StringUtils.hasText(this.regexp) && this.predicate != null);
+		}
+
 	}
 
 }

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/route/builder/PredicateSpec.java

@@ -204,6 +204,18 @@ public <T> BooleanSpec readBody(Class<T> inClass, Predicate<T> predicate) {
 				getBean(ReadBodyRoutePredicateFactory.class).applyAsync(c -> c.setPredicate(inClass, predicate)));
 	}
 
+	/**
+	 * A predicate that checks if a query parameter value matches criteria of a given
+	 * predicate.
+	 * @param param the query parameter name
+	 * @param predicate a predicate to check the value of the param
+	 * @return a {@link BooleanSpec} to be used to add logical operators
+	 */
+	public BooleanSpec query(String param, Predicate<String> predicate) {
+		return asyncPredicate(
+				getBean(QueryRoutePredicateFactory.class).applyAsync(c -> c.setParam(param).setPredicate(predicate)));
+	}
+
 	/**
 	 * A predicate that checks if a query parameter matches a regular expression.
 	 * @param param the query parameter name
@@ -287,7 +299,7 @@ public BooleanSpec xForwardedRemoteAddr(String... addrs) {
 	 */
 	public BooleanSpec weight(String group, int weight) {
 		return asyncPredicate(getBean(WeightRoutePredicateFactory.class)
-			.applyAsync(c -> c.setGroup(group).setRouteId(routeBuilder.getId()).setWeight(weight)));
+			.applyAsync(c -> c.setGroup(group).setRouteId(this.routeBuilder.getId()).setWeight(weight)));
 	}
 
 	public BooleanSpec cloudFoundryRouteService() {

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/handler/predicate/QueryRoutePredicateFactoryPredicateTests.java

@@ -0,0 +1,141 @@
+/*
+ * Copyright 2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.gateway.handler.predicate;
+
+import java.util.function.Predicate;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.system.CapturedOutput;
+import org.springframework.boot.test.system.OutputCaptureExtension;
+import org.springframework.cloud.gateway.handler.predicate.QueryRoutePredicateFactory.Config;
+import org.springframework.cloud.gateway.route.RouteLocator;
+import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
+import org.springframework.cloud.gateway.support.HasConfig;
+import org.springframework.cloud.gateway.test.BaseWebClientTests;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.web.server.ServerWebExchange;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
+
+/**
+ * Test class for {@link QueryRoutePredicateFactory} for <code>predicate</code> parameter.
+ *
+ * @see QueryRoutePredicateFactory
+ */
+@SpringBootTest(webEnvironment = RANDOM_PORT)
+@DirtiesContext
+@ExtendWith(OutputCaptureExtension.class)
+public class QueryRoutePredicateFactoryPredicateTests extends BaseWebClientTests {
+
+	@Test
+	public void noQueryParamWorks(CapturedOutput output) {
+		this.testClient.get()
+			.uri("/get")
+			.exchange()
+			.expectStatus()
+			.isOk()
+			.expectHeader()
+			.valueEquals(ROUTE_ID_HEADER, "default_path_to_httpbin");
+		assertThat(output).doesNotContain("Error applying predicate for route: foo_query_param");
+	}
+
+	@Test
+	public void queryParamPredicateTrue() {
+		this.testClient.get()
+			.uri("/get?foo=1234567")
+			.exchange()
+			.expectStatus()
+			.isOk()
+			.expectHeader()
+			.valueEquals(ROUTE_ID_HEADER, "foo_query_param");
+	}
+
+	@Test
+	public void queryParamPredicateFalse(CapturedOutput output) {
+		this.testClient.get()
+			.uri("/get?foo=123")
+			.exchange()
+			.expectStatus()
+			.isOk()
+			.expectHeader()
+			.valueEquals(ROUTE_ID_HEADER, "default_path_to_httpbin");
+		assertThat(output).doesNotContain("Error applying predicate for route: foo_query_param");
+	}
+
+	@Test
+	public void emptyQueryParamWorks(CapturedOutput output) {
+		this.testClient.get()
+			.uri("/get?foo")
+			.exchange()
+			.expectStatus()
+			.isOk()
+			.expectHeader()
+			.valueEquals(ROUTE_ID_HEADER, "default_path_to_httpbin");
+		assertThat(output).doesNotContain("Error applying predicate for route: foo_query_param");
+	}
+
+	@Test
+	public void testConfig() {
+		Config config = new Config();
+		config.setParam("query_param");
+		Predicate<ServerWebExchange> predicate = new QueryRoutePredicateFactory().apply(config);
+		assertThat(predicate).isInstanceOf(HasConfig.class);
+		assertThat(config).isSameAs(((HasConfig) predicate).getConfig());
+	}
+
+	@Test
+	public void toStringFormat() {
+		Config config = new Config();
+		config.setParam("query_param");
+		Predicate<ServerWebExchange> predicate = new QueryRoutePredicateFactory().apply(config);
+		assertThat(predicate.toString()).contains("Query: param=query_param");
+	}
+
+	@EnableAutoConfiguration
+	@SpringBootConfiguration
+	@Import(DefaultTestConfig.class)
+	public static class TestConfig {
+
+		private static final int PARAM_LENGTH = 5;
+
+		@Value("${test.uri}")
+		private String uri;
+
+		@Bean
+		RouteLocator queryRouteLocator(RouteLocatorBuilder builder) {
+			return builder.routes()
+				.route("foo_query_param",
+						r -> r.query("foo", queryParamPredicate()).filters(f -> f.prefixPath("/httpbin")).uri(this.uri))
+				.build();
+		}
+
+		private Predicate<String> queryParamPredicate() {
+			return p -> p == null ? false : p.length() > PARAM_LENGTH;
+		}
+
+	}
+
+}

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/handler/predicate/QueryRoutePredicateFactoryTests.java

@@ -38,14 +38,19 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
 
+/**
+ * Test class for {@link QueryRoutePredicateFactory} for <code>regex</code> parameter.
+ *
+ * @see QueryRoutePredicateFactory
+ */
 @SpringBootTest(webEnvironment = RANDOM_PORT)
 @DirtiesContext
 @ExtendWith(OutputCaptureExtension.class)
 public class QueryRoutePredicateFactoryTests extends BaseWebClientTests {
 
 	@Test
 	public void noQueryParamWorks(CapturedOutput output) {
-		testClient.get()
+		this.testClient.get()
 			.uri("/get")
 			.exchange()
 			.expectStatus()
@@ -57,7 +62,7 @@ public void noQueryParamWorks(CapturedOutput output) {
 
 	@Test
 	public void queryParamWorks() {
-		testClient.get()
+		this.testClient.get()
 			.uri("/get?foo=bar")
 			.exchange()
 			.expectStatus()
@@ -68,7 +73,7 @@ public void queryParamWorks() {
 
 	@Test
 	public void emptyQueryParamWorks(CapturedOutput output) {
-		testClient.get()
+		this.testClient.get()
 			.uri("/get?foo")
 			.exchange()
 			.expectStatus()
@@ -98,7 +103,8 @@ public static class TestConfig {
 		@Bean
 		RouteLocator queryRouteLocator(RouteLocatorBuilder builder) {
 			return builder.routes()
-				.route("foo_query_param", r -> r.query("foo", "bar").filters(f -> f.prefixPath("/httpbin")).uri(uri))
+				.route("foo_query_param",
+						r -> r.query("foo", "bar").filters(f -> f.prefixPath("/httpbin")).uri(this.uri))
 				.build();
 		}
 

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/test/AdhocTestSuite.java

@@ -46,6 +46,7 @@
 		org.springframework.cloud.gateway.handler.predicate.MethodRoutePredicateFactoryTests.class,
 		org.springframework.cloud.gateway.handler.predicate.BetweenRoutePredicateFactoryTests.class,
 		org.springframework.cloud.gateway.handler.predicate.QueryRoutePredicateFactoryTests.class,
+		org.springframework.cloud.gateway.handler.predicate.QueryRoutePredicateFactoryPredicateTests.class,
 		org.springframework.cloud.gateway.handler.predicate.WeightRoutePredicateFactoryIntegrationTests.class,
 		org.springframework.cloud.gateway.handler.predicate.HeaderRoutePredicateFactoryTests.class,
 		org.springframework.cloud.gateway.handler.predicate.BeforeRoutePredicateFactoryTests.class,