Fix #1878

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -20,6 +20,8 @@ Project: jackson-databind
 #1870: Remove `final` on inherited methods in `BuilderBasedDeserializer` to allow
   overriding by subclasses
   (requested by Ville K)
+#1878: `@JsonBackReference` property is always ignored when deserializing since 2.9.0
+ (reported by reda-alaoui@github)
 
 2.9.3 (09-Dec-2017)
 

src/main/java/com/fasterxml/jackson/databind/deser/BeanDeserializerBuilder.java

@@ -195,12 +195,15 @@ public void  addBackReferenceProperty(String referenceName, SettableBeanProperty
         //    access set early; unfortunate, but since it works....
         prop.fixAccess(_config);
         _backRefProperties.put(referenceName, prop);
-        // also: if we had property with same name, actually remove it
+        // 16-Jan-2018, tatu: As per [databind#1878] we may want to leave it as is, to allow
+        //    population for cases of "wrong direction", traversing parent first
+        //   If this causes problems should probably instead include in "ignored properties" list
+        //   Alternatively could also extend annotation to allow/disallow explicit value from input
+        /*
         if (_properties != null) {
-            _properties.remove(referenceName);
+            _properties.remove(prop.getName());
         }
-        // ??? 23-Jul-2012, tatu: Should it be included in list of all properties?
-        //   For now, won't add, since it is inferred, not explicit...
+        */
     }
 
     public void addInjectable(PropertyName propName, JavaType propType,

src/test/java/com/fasterxml/jackson/failing/BackReference1878Test.java renamed to src/test/java/com/fasterxml/jackson/databind/struct/BackReference1878Test.java

@@ -1,18 +1,16 @@
-package com.fasterxml.jackson.failing;
+package com.fasterxml.jackson.databind.struct;
 
 import com.fasterxml.jackson.annotation.JsonBackReference;
 import com.fasterxml.jackson.annotation.JsonManagedReference;
+
 import com.fasterxml.jackson.databind.BaseMapTest;
-import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 /**
- * Created on 09/01/18.
- *
  * @author Reda.Housni-Alaoui
  */
-public class BackReference1878Test extends BaseMapTest {
-
+public class BackReference1878Test extends BaseMapTest
+{
     static class Child {
         @JsonBackReference
         public Parent b;
@@ -26,9 +24,7 @@ static class Parent {
     private final ObjectMapper MAPPER = new ObjectMapper();
 
     public void testChildDeserialization() throws Exception {
-        MAPPER.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
         Child child = MAPPER.readValue("{\"b\": {}}", Child.class);
         assertNotNull(child.b);
     }
-
 }