Support for indexing into any Collection/Iterable

Closes gh-907

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/AbstractNestablePropertyAccessor.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.
@@ -30,7 +30,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.Set;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -657,22 +656,32 @@ else if (value instanceof List list) {
 						growCollectionIfNecessary(list, index, indexedPropertyName.toString(), ph, i + 1);
 						value = list.get(index);
 					}
-					else if (value instanceof Set set) {
-						// Apply index to Iterator in case of a Set.
+					else if (value instanceof Iterable iterable) {
+						// Apply index to Iterator in case of a Set/Collection/Iterable.
 						int index = Integer.parseInt(key);
-						if (index < 0 || index >= set.size()) {
-							throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
-									"Cannot get element with index " + index + " from Set of size " +
-											set.size() + ", accessed using property path '" + propertyName + "'");
+						if (value instanceof Collection<?> coll) {
+							if (index < 0 || index >= coll.size()) {
+								throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
+										"Cannot get element with index " + index + " from Collection of size " +
+												coll.size() + ", accessed using property path '" + propertyName + "'");
+							}
 						}
-						Iterator<Object> it = set.iterator();
-						for (int j = 0; it.hasNext(); j++) {
+						Iterator<Object> it = iterable.iterator();
+						boolean found = false;
+						int currIndex = 0;
+						for (; it.hasNext(); currIndex++) {
 							Object elem = it.next();
-							if (j == index) {
+							if (currIndex == index) {
 								value = elem;
+								found = true;
 								break;
 							}
 						}
+						if (!found) {
+							throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
+									"Cannot get element with index " + index + " from Iterable of size " +
+											currIndex + ", accessed using property path '" + propertyName + "'");
+						}
 					}
 					else if (value instanceof Map map) {
 						Class<?> mapKeyType = ph.getResolvableType().getNested(i + 1).asMap().resolveGeneric(0);
@@ -685,13 +694,17 @@ else if (value instanceof Map map) {
 					else {
 						throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
 								"Property referenced in indexed property path '" + propertyName +
-										"' is neither an array nor a List nor a Set nor a Map; returned value was [" + value + "]");
+										"' is neither an array nor a List/Set/Collection/Iterable nor a Map; " +
+										"returned value was [" + value + "]");
 					}
 					indexedPropertyName.append(PROPERTY_KEY_PREFIX).append(key).append(PROPERTY_KEY_SUFFIX);
 				}
 			}
 			return value;
 		}
+		catch (InvalidPropertyException ex) {
+			throw ex;
+		}
 		catch (IndexOutOfBoundsException ex) {
 			throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
 					"Index of out of bounds in property path '" + propertyName + "'", ex);

spring-beans/src/test/java/org/springframework/beans/AbstractPropertyAccessorTests.java

@@ -139,12 +139,14 @@ void isReadableWritableForIndexedProperties() {
 		assertThat(accessor.isReadableProperty("list")).isTrue();
 		assertThat(accessor.isReadableProperty("set")).isTrue();
 		assertThat(accessor.isReadableProperty("map")).isTrue();
+		assertThat(accessor.isReadableProperty("myTestBeans")).isTrue();
 		assertThat(accessor.isReadableProperty("xxx")).isFalse();
 
 		assertThat(accessor.isWritableProperty("array")).isTrue();
 		assertThat(accessor.isWritableProperty("list")).isTrue();
 		assertThat(accessor.isWritableProperty("set")).isTrue();
 		assertThat(accessor.isWritableProperty("map")).isTrue();
+		assertThat(accessor.isWritableProperty("myTestBeans")).isTrue();
 		assertThat(accessor.isWritableProperty("xxx")).isFalse();
 
 		assertThat(accessor.isReadableProperty("array[0]")).isTrue();
@@ -159,6 +161,8 @@ void isReadableWritableForIndexedProperties() {
 		assertThat(accessor.isReadableProperty("map[key4][0].name")).isTrue();
 		assertThat(accessor.isReadableProperty("map[key4][1]")).isTrue();
 		assertThat(accessor.isReadableProperty("map[key4][1].name")).isTrue();
+		assertThat(accessor.isReadableProperty("myTestBeans[0]")).isTrue();
+		assertThat(accessor.isReadableProperty("myTestBeans[1]")).isFalse();
 		assertThat(accessor.isReadableProperty("array[key1]")).isFalse();
 
 		assertThat(accessor.isWritableProperty("array[0]")).isTrue();
@@ -173,6 +177,8 @@ void isReadableWritableForIndexedProperties() {
 		assertThat(accessor.isWritableProperty("map[key4][0].name")).isTrue();
 		assertThat(accessor.isWritableProperty("map[key4][1]")).isTrue();
 		assertThat(accessor.isWritableProperty("map[key4][1].name")).isTrue();
+		assertThat(accessor.isReadableProperty("myTestBeans[0]")).isTrue();
+		assertThat(accessor.isReadableProperty("myTestBeans[1]")).isFalse();
 		assertThat(accessor.isWritableProperty("array[key1]")).isFalse();
 	}
 
@@ -1388,6 +1394,7 @@ void getAndSetIndexedProperties() {
 		assertThat(accessor.getPropertyValue("map[key5[foo]].name")).isEqualTo("name8");
 		assertThat(accessor.getPropertyValue("map['key5[foo]'].name")).isEqualTo("name8");
 		assertThat(accessor.getPropertyValue("map[\"key5[foo]\"].name")).isEqualTo("name8");
+		assertThat(accessor.getPropertyValue("myTestBeans[0].name")).isEqualTo("nameZ");
 
 		MutablePropertyValues pvs = new MutablePropertyValues();
 		pvs.add("array[0].name", "name5");
@@ -1401,6 +1408,7 @@ void getAndSetIndexedProperties() {
 		pvs.add("map[key4][0].name", "nameA");
 		pvs.add("map[key4][1].name", "nameB");
 		pvs.add("map[key5[foo]].name", "name10");
+		pvs.add("myTestBeans[0].name", "nameZZ");
 		accessor.setPropertyValues(pvs);
 		assertThat(tb0.getName()).isEqualTo("name5");
 		assertThat(tb1.getName()).isEqualTo("name4");
@@ -1419,6 +1427,7 @@ void getAndSetIndexedProperties() {
 		assertThat(accessor.getPropertyValue("map[key4][0].name")).isEqualTo("nameA");
 		assertThat(accessor.getPropertyValue("map[key4][1].name")).isEqualTo("nameB");
 		assertThat(accessor.getPropertyValue("map[key5[foo]].name")).isEqualTo("name10");
+		assertThat(accessor.getPropertyValue("myTestBeans[0].name")).isEqualTo("nameZZ");
 	}
 
 	@Test

spring-beans/src/testFixtures/java/org/springframework/beans/testfixture/beans/IndexedTestBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 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.
@@ -17,8 +17,10 @@
 package org.springframework.beans.testfixture.beans;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -47,6 +49,8 @@ public class IndexedTestBean {
 
 	private SortedMap sortedMap;
 
+	private MyTestBeans myTestBeans;
+
 
 	public IndexedTestBean() {
 		this(true);
@@ -71,6 +75,7 @@ public void populate() {
 		TestBean tb8 = new TestBean("name8", 0);
 		TestBean tbX = new TestBean("nameX", 0);
 		TestBean tbY = new TestBean("nameY", 0);
+		TestBean tbZ = new TestBean("nameZ", 0);
 		this.array = new TestBean[] {tb0, tb1};
 		this.list = new ArrayList<>();
 		this.list.add(tb2);
@@ -87,6 +92,7 @@ public void populate() {
 		list.add(tbY);
 		this.map.put("key4", list);
 		this.map.put("key5[foo]", tb8);
+		this.myTestBeans = new MyTestBeans(tbZ);
 	}
 
 
@@ -146,4 +152,27 @@ public void setSortedMap(SortedMap sortedMap) {
 		this.sortedMap = sortedMap;
 	}
 
+	public MyTestBeans getMyTestBeans() {
+		return myTestBeans;
+	}
+
+	public void setMyTestBeans(MyTestBeans myTestBeans) {
+		this.myTestBeans = myTestBeans;
+	}
+
+
+	public static class MyTestBeans implements Iterable<TestBean> {
+
+		private final Collection<TestBean> testBeans;
+
+		public MyTestBeans(TestBean... testBeans) {
+			this.testBeans = Arrays.asList(testBeans);
+		}
+
+		@Override
+		public Iterator<TestBean> iterator() {
+			return this.testBeans.iterator();
+		}
+	}
+
 }