DATACMNS-867 - Preserve underscores when resolving PropertyPath for PersistentProperties.

Preserve underscores in variable names (eg. String foo_bar) when resolving the actual type information for the property via PropertyPath by quoting (Pattern#quote) the property name.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2014 the original author or authors.
+ * Copyright 2011-2017 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.
@@ -36,6 +36,7 @@ import org.springframework.util.StringUtils;
  * Abstraction of a {@link PropertyPath} of a domain class.
  * 
  * @author Oliver Gierke
+ * @author Christoph Strobl
  */
 @EqualsAndHashCode
 public class PropertyPath implements Streamable<PropertyPath> {
@@ -43,6 +44,7 @@ public class PropertyPath implements Streamable<PropertyPath> {
 	private static final String DELIMITERS = "_\\.";
 	private static final String ALL_UPPERCASE = "[A-Z0-9._$]+";
 	private static final Pattern SPLITTER = Pattern.compile("(?:[%s]?([%s]*?[^%s]+))".replaceAll("%s", DELIMITERS));
+	private static final Pattern SPLITTER_FOR_QUOTED = Pattern.compile("(?:[%s]?([%s]*?[^%s]+))".replaceAll("%s", "\\."));
 
 	private final TypeInformation<?> owningType;
 	private final String name;
@@ -59,7 +61,7 @@ public class PropertyPath implements Streamable<PropertyPath> {
 	 * @param owningType must not be {@literal null}.
 	 */
 	PropertyPath(String name, Class<?> owningType) {
-		this(name, ClassTypeInformation.from(owningType), Collections.<PropertyPath>emptyList());
+		this(name, ClassTypeInformation.from(owningType), Collections.<PropertyPath> emptyList());
 	}
 
 	/**
@@ -210,8 +212,9 @@ public class PropertyPath implements Streamable<PropertyPath> {
 	}
 
 	/**
-	 * Extracts the {@link PropertyPath} chain from the given source {@link String} and {@link TypeInformation}.
-	 * 
+	 * Extracts the {@link PropertyPath} chain from the given source {@link String} and {@link TypeInformation}. <br />
+	 * Uses {@link #SPLITTER} by default and {@link #SPLITTER_FOR_QUOTED} for {@link Pattern#quote(String) quoted} literals.
+	 *
 	 * @param source must not be {@literal null}.
 	 * @param type
 	 * @return
@@ -222,7 +225,9 @@ public class PropertyPath implements Streamable<PropertyPath> {
 		Assert.notNull(type, "TypeInformation must not be null or empty!");
 
 		List<String> iteratorSource = new ArrayList<>();
-		Matcher matcher = SPLITTER.matcher("_" + source);
+
+		Matcher matcher = isQuoted(source) ? SPLITTER_FOR_QUOTED.matcher(source.replace("\\Q", "").replace("\\E", ""))
+				: SPLITTER.matcher("_" + source);
 
 		while (matcher.find()) {
 			iteratorSource.add(matcher.group(1));
@@ -245,6 +250,10 @@ public class PropertyPath implements Streamable<PropertyPath> {
 		return result;
 	}
 
+	private static boolean isQuoted(String source) {
+		return source.matches("^\\\\Q.*\\\\E$");
+	}
+
 	/**
 	 * Creates a new {@link PropertyPath} as subordinary of the given {@link PropertyPath}.
 	 * 

src/main/java/org/springframework/data/mapping/model/AbstractPersistentProperty.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2015 the original author or authors.
+ * Copyright 2011-2017 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.
@@ -23,6 +23,7 @@ import java.lang.reflect.Method;
 import java.util.Collections;
 import java.util.Map;
 import java.util.Optional;
+import java.util.regex.Pattern;
 
 import org.springframework.data.annotation.Reference;
 import org.springframework.data.mapping.Association;
@@ -66,8 +67,7 @@ public abstract class AbstractPersistentProperty<P extends PersistentProperty<P>
 
 		this.name = property.getName();
 		this.rawType = property.getType();
-
-		this.information = PropertyPath.from(property.getName(), owner.getTypeInformation()).getTypeInformation();
+		this.information = PropertyPath.from(Pattern.quote(property.getName()), owner.getTypeInformation()).getTypeInformation();
 		this.property = property;
 		this.association = isAssociation() ? Optional.of(createAssociation()) : Optional.empty();
 		this.owner = owner;

src/test/java/org/springframework/data/mapping/PropertyPathUnitTests.java

@@ -21,6 +21,7 @@ import static org.springframework.data.mapping.PropertyPath.*;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
+import java.util.regex.Pattern;
 
 import org.junit.Rule;
 import org.junit.Test;
@@ -32,6 +33,7 @@ import org.springframework.data.util.TypeInformation;
  * Unit tests for {@link PropertyPath}.
  * 
  * @author Oliver Gierke
+ * @author Christoph Strobl
  */
 @SuppressWarnings("unused")
 public class PropertyPathUnitTests {
@@ -333,11 +335,22 @@ public class PropertyPathUnitTests {
 		from("userAme", Foo.class);
 	}
 
+	@Test // DATACMNS-867
+	public void preservesUnderscoresForQuotedNames() {
+
+		PropertyPath path = from(Pattern.quote("var_name_with_underscore"), Foo.class);
+
+		assertThat(path).isNotNull();
+		assertThat(path.getSegment()).isEqualTo("var_name_with_underscore");
+		assertThat(path.hasNext()).isFalse();
+	}
+
 	private class Foo {
 
 		String userName;
 		String _email;
 		String UUID;
+		String var_name_with_underscore;
 	}
 
 	private class Bar {

src/test/java/org/springframework/data/mapping/model/AbstractPersistentPropertyUnitTests.java

@@ -43,6 +43,7 @@ import org.springframework.util.ReflectionUtils;
  * Unit tests for {@link AbstractPersistentProperty}.
  * 
  * @author Oliver Gierke
+ * @author Christoph Strobl
  */
 public class AbstractPersistentPropertyUnitTests {
 
@@ -192,6 +193,13 @@ public class AbstractPersistentPropertyUnitTests {
 		assertThat(property.isEntity()).isFalse();
 	}
 
+	@Test // DATACMNS-867
+	public void resolvesFieldNameWithUnderscoresCorrectly() {
+
+		SamplePersistentProperty property = getProperty(TestClassComplex.class, "var_name_with_underscores");
+		assertThat(property.getName()).isEqualTo("var_name_with_underscores");
+	}
+
 	private <T> BasicPersistentEntity<T, SamplePersistentProperty> getEntity(Class<T> type) {
 		return new BasicPersistentEntity<>(ClassTypeInformation.from(type));
 	}
@@ -244,6 +252,7 @@ public class AbstractPersistentPropertyUnitTests {
 		Map map;
 		Collection collection;
 		transient Object transientField;
+		String var_name_with_underscores;
 	}
 
 	class AccessorTestClass {