Support BindParam annotation

Allows customizing the name of the request parameter to bind a
constructor parameter to.

Closes gh-30947

spring-context/src/test/java/org/springframework/validation/DataBinderConstructTests.java

@@ -0,0 +1,154 @@
+/*
+ * Copyright 2002-2023 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.validation;
+
+import java.beans.ConstructorProperties;
+import java.util.Map;
+import java.util.Optional;
+
+import jakarta.validation.constraints.NotNull;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.core.ResolvableType;
+import org.springframework.format.support.DefaultFormattingConversionService;
+import org.springframework.util.Assert;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for {@link DataBinder} with constructor binding.
+ *
+ * @author Rossen Stoyanchev
+ */
+public class DataBinderConstructTests {
+
+
+	@Test
+	void dataClassBinding() {
+		MapValueResolver valueResolver = new MapValueResolver(Map.of("param1", "value1", "param2", "true"));
+		DataBinder binder = initDataBinder(DataClass.class);
+		binder.construct(valueResolver);
+
+		DataClass dataClass = getTarget(binder);
+		assertThat(dataClass.param1()).isEqualTo("value1");
+		assertThat(dataClass.param2()).isEqualTo(true);
+		assertThat(dataClass.param3()).isEqualTo(0);
+	}
+
+	@Test
+	void dataClassBindingWithOptionalParameter() {
+		MapValueResolver valueResolver =
+				new MapValueResolver(Map.of("param1", "value1", "param2", "true", "optionalParam", "8"));
+
+		DataBinder binder = initDataBinder(DataClass.class);
+		binder.construct(valueResolver);
+
+		DataClass dataClass = getTarget(binder);
+		assertThat(dataClass.param1()).isEqualTo("value1");
+		assertThat(dataClass.param2()).isEqualTo(true);
+		assertThat(dataClass.param3()).isEqualTo(8);
+	}
+
+	@Test
+	void dataClassBindingWithMissingParameter() {
+		MapValueResolver valueResolver = new MapValueResolver(Map.of("param1", "value1"));
+		DataBinder binder = initDataBinder(DataClass.class);
+		binder.construct(valueResolver);
+
+		BindingResult bindingResult = binder.getBindingResult();
+		assertThat(bindingResult.getAllErrors()).hasSize(1);
+		assertThat(bindingResult.getFieldValue("param1")).isEqualTo("value1");
+		assertThat(bindingResult.getFieldValue("param2")).isNull();
+		assertThat(bindingResult.getFieldValue("param3")).isNull();
+	}
+
+	@Test
+	void dataClassBindingWithConversionError() {
+		MapValueResolver valueResolver = new MapValueResolver(Map.of("param1", "value1", "param2", "x"));
+		DataBinder binder = initDataBinder(DataClass.class);
+		binder.construct(valueResolver);
+
+		BindingResult bindingResult = binder.getBindingResult();
+		assertThat(bindingResult.getAllErrors()).hasSize(1);
+		assertThat(bindingResult.getFieldValue("param1")).isEqualTo("value1");
+		assertThat(bindingResult.getFieldValue("param2")).isEqualTo("x");
+		assertThat(bindingResult.getFieldValue("param3")).isNull();
+	}
+
+	@SuppressWarnings("SameParameterValue")
+	private static DataBinder initDataBinder(Class<DataClass> targetType) {
+		DataBinder binder = new DataBinder(null);
+		binder.setTargetType(ResolvableType.forClass(targetType));
+		binder.setConversionService(new DefaultFormattingConversionService());
+		return binder;
+	}
+
+	@SuppressWarnings("unchecked")
+	private static <T> T getTarget(DataBinder dataBinder) {
+		assertThat(dataBinder.getBindingResult().getAllErrors()).isEmpty();
+		Object target = dataBinder.getTarget();
+		assertThat(target).isNotNull();
+		return (T) target;
+	}
+
+
+	private static class DataClass {
+
+		@NotNull
+		private final String param1;
+
+		private final boolean param2;
+
+		private int param3;
+
+		@ConstructorProperties({"param1", "param2", "optionalParam"})
+		DataClass(String param1, boolean p2, Optional<Integer> optionalParam) {
+			this.param1 = param1;
+			this.param2 = p2;
+			Assert.notNull(optionalParam, "Optional must not be null");
+			optionalParam.ifPresent(integer -> this.param3 = integer);
+		}
+
+		public String param1() {
+			return this.param1;
+		}
+
+		public boolean param2() {
+			return this.param2;
+		}
+
+		public int param3() {
+			return this.param3;
+		}
+	}
+
+
+	private static class MapValueResolver implements DataBinder.ValueResolver {
+
+		private final Map<String, Object> values;
+
+		private MapValueResolver(Map<String, Object> values) {
+			this.values = values;
+		}
+
+		@Override
+		public Object resolveValue(String name, Class<?> type) {
+			return values.get(name);
+		}
+	}
+
+}