Expose MethodParameter in MissingServletRequestParameterException

See gh-26219

spring-web/src/main/java/org/springframework/web/bind/MissingServletRequestParameterException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * 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.
@@ -16,6 +16,9 @@
 
 package org.springframework.web.bind;
 
+import org.springframework.core.MethodParameter;
+import org.springframework.lang.Nullable;
+
 /**
  * {@link ServletRequestBindingException} subclass that indicates a missing parameter.
  *
@@ -29,14 +32,38 @@ public class MissingServletRequestParameterException extends MissingRequestValue
 
 	private final String parameterType;
 
+	@Nullable
+	private final MethodParameter parameter;
+
 
 	/**
 	 * Constructor for MissingServletRequestParameterException.
 	 * @param parameterName the name of the missing parameter
 	 * @param parameterType the expected type of the missing parameter
 	 */
 	public MissingServletRequestParameterException(String parameterName, String parameterType) {
-		this(parameterName, parameterType, false);
+		super("", false, null, new Object[] {parameterName});
+		this.parameterName = parameterName;
+		this.parameterType = parameterType;
+		this.parameter = null;
+		getBody().setDetail(initBodyDetail(this.parameterName));
+	}
+
+	/**
+	 * Constructor with a {@link MethodParameter} instead of a String parameterType.
+	 * @param parameterName the name of the missing parameter
+	 * @param parameter the target method parameter for the missing value
+	 * @param missingAfterConversion whether the value became null after conversion
+	 * @since 6.1
+	 */
+	public MissingServletRequestParameterException(
+			String parameterName, MethodParameter parameter, boolean missingAfterConversion) {
+
+		super("", missingAfterConversion, null, new Object[] {parameterName});
+		this.parameterName = parameterName;
+		this.parameterType = parameter.getNestedParameterType().getSimpleName();
+		this.parameter = parameter;
+		getBody().setDetail(initBodyDetail(this.parameterName));
 	}
 
 	/**
@@ -45,14 +72,21 @@ public MissingServletRequestParameterException(String parameterName, String para
 	 * @param parameterType the expected type of the missing parameter
 	 * @param missingAfterConversion whether the value became null after conversion
 	 * @since 5.3.6
+	 * @deprecated in favor of {@link #MissingServletRequestParameterException(String, MethodParameter, boolean)}
 	 */
+	@Deprecated(since = "6.1", forRemoval = true)
 	public MissingServletRequestParameterException(
 			String parameterName, String parameterType, boolean missingAfterConversion) {
 
 		super("", missingAfterConversion, null, new Object[] {parameterName});
 		this.parameterName = parameterName;
 		this.parameterType = parameterType;
-		getBody().setDetail("Required parameter '" + this.parameterName + "' is not present.");
+		this.parameter = null;
+		getBody().setDetail(initBodyDetail(this.parameterName));
+	}
+
+	private static String initBodyDetail(String name) {
+		return "Required parameter '" + name + "' is not present.";
 	}
 
 
@@ -77,4 +111,14 @@ public final String getParameterType() {
 		return this.parameterType;
 	}
 
+	/**
+	 * Return the target {@link MethodParameter} if the exception was raised for
+	 * a controller method argument.
+	 * @since 6.1
+	 */
+	@Nullable
+	public MethodParameter getMethodParameter() {
+		return this.parameter;
+	}
+
 }

spring-web/src/main/java/org/springframework/web/method/annotation/RequestParamMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * 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.
@@ -214,8 +214,7 @@ protected void handleMissingValueInternal(
 			}
 		}
 		else {
-			throw new MissingServletRequestParameterException(name,
-					parameter.getNestedParameterType().getSimpleName(), missingAfterConversion);
+			throw new MissingServletRequestParameterException(name, parameter, missingAfterConversion);
 		}
 	}