DATACMNS-387 - Improvements in null handling in PartTree area.

We're now rejecting invalid constructor arguments handed to ClassTypeInformation, Part, PartTree and PropertyPath. Beyond that we skip the creation of a Part for an empty path segment, so that you don't end up with an invalid Part instance for a findAllByOrderByFooAsc.

src/main/java/org/springframework/data/mapping/PropertyPath.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -53,7 +53,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @param owningType must not be {@literal null}.
 	 */
 	PropertyPath(String name, Class<?> owningType) {
-
 		this(name, ClassTypeInformation.from(owningType), null);
 	}
 
@@ -133,7 +132,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @see #hasNext()
 	 */
 	public PropertyPath next() {
-
 		return next;
 	}
 
@@ -144,7 +142,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @return
 	 */
 	public boolean hasNext() {
-
 		return next != null;
 	}
 
@@ -168,7 +165,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @return
 	 */
 	public boolean isCollection() {
-
 		return isCollection;
 	}
 
@@ -242,7 +238,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @return
 	 */
 	public static PropertyPath from(String source, Class<?> type) {
-
 		return from(source, ClassTypeInformation.from(type));
 	}
 
@@ -255,6 +250,9 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 */
 	public static PropertyPath from(String source, TypeInformation<?> type) {
 
+		Assert.hasText(source, "Source must not be null or empty!");
+		Assert.notNull(type, "TypeInformation must not be null or empty!");
+
 		List<String> iteratorSource = new ArrayList<String>();
 		Matcher matcher = SPLITTER.matcher("_" + source);
 
@@ -306,7 +304,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @return
 	 */
 	private static PropertyPath create(String source, TypeInformation<?> type, Stack<PropertyPath> base) {
-
 		return create(source, type, "", base);
 	}
 

src/main/java/org/springframework/data/repository/query/parser/Part.java

@@ -24,6 +24,7 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import org.springframework.data.mapping.PropertyPath;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -46,25 +47,27 @@ public class Part {
 	 * Creates a new {@link Part} from the given method name part, the {@link Class} the part originates from and the
 	 * start parameter index.
 	 * 
-	 * @param part must not be {@literal null}.
+	 * @param source must not be {@literal null}.
 	 * @param clazz must not be {@literal null}.
 	 */
-	public Part(String part, Class<?> clazz) {
-
-		this(part, clazz, false);
+	public Part(String source, Class<?> clazz) {
+		this(source, clazz, false);
 	}
 
 	/**
 	 * Creates a new {@link Part} from the given method name part, the {@link Class} the part originates from and the
 	 * start parameter index.
 	 * 
-	 * @param part must not be {@literal null}.
+	 * @param source must not be {@literal null}.
 	 * @param clazz must not be {@literal null}.
 	 * @param alwaysIgnoreCase
 	 */
-	public Part(String part, Class<?> clazz, boolean alwaysIgnoreCase) {
+	public Part(String source, Class<?> clazz, boolean alwaysIgnoreCase) {
 
-		String partToUse = detectAndSetIgnoreCase(part);
+		Assert.hasText(source, "Part source must not be null or emtpy!");
+		Assert.notNull(clazz, "Type must not be null!");
+
+		String partToUse = detectAndSetIgnoreCase(source);
 		if (alwaysIgnoreCase && ignoreCase != IgnoreCaseType.ALWAYS) {
 			this.ignoreCase = IgnoreCaseType.WHEN_POSSIBLE;
 		}

src/main/java/org/springframework/data/repository/query/parser/PartTree.java

@@ -197,7 +197,9 @@ public class PartTree implements Iterable<OrPart> {
 
 			String[] split = split(source, "And");
 			for (String part : split) {
-				children.add(new Part(part, domainClass, alwaysIgnoreCase));
+				if (StringUtils.hasText(part)) {
+					children.add(new Part(part, domainClass, alwaysIgnoreCase));
+				}
 			}
 		}
 

src/main/java/org/springframework/data/util/ClassTypeInformation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -29,6 +29,7 @@ import java.util.Set;
 import java.util.WeakHashMap;
 
 import org.springframework.core.GenericTypeResolver;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -60,11 +61,13 @@ public class ClassTypeInformation<S> extends TypeDiscoverer<S> {
 	 * Simple factory method to easily create new instances of {@link ClassTypeInformation}.
 	 * 
 	 * @param <S>
-	 * @param type
+	 * @param type must not be {@literal null}.
 	 * @return
 	 */
 	public static <S> TypeInformation<S> from(Class<S> type) {
 
+		Assert.notNull(type, "Type must not be null!");
+
 		Reference<TypeInformation<?>> cachedReference = CACHE.get(type);
 		TypeInformation<?> cachedTypeInfo = cachedReference == null ? null : cachedReference.get();
 
@@ -80,10 +83,12 @@ public class ClassTypeInformation<S> extends TypeDiscoverer<S> {
 	/**
 	 * Creates a {@link TypeInformation} from the given method's return type.
 	 * 
-	 * @param method
+	 * @param method must not be {@literal null}.
 	 * @return
 	 */
 	public static <S> TypeInformation<S> fromReturnTypeOf(Method method) {
+
+		Assert.notNull(method, "Method must not be null!");
 		return new ClassTypeInformation(method.getDeclaringClass()).createInfo(method.getGenericReturnType());
 	}