Fix #1804

Author: cowtowncoder

release-notes/VERSION

@@ -10,7 +10,8 @@ Project: jackson-databind
  (reported by nhtzr@github)
 #1768: Improve `TypeFactory.constructFromCanonical()` to work with
   `java.lang.reflect.Type.getTypeName()` format
-
+#1804: `ValueInstantiator.canInstantiate()` ignores `canCreateUsingArrayDelegate()`
+ (reported byb henryptung@github)
 
 2.8.10 (24-Aug-2017)
 

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

@@ -281,9 +281,6 @@ public JsonDeserializer<Object> buildBeanDeserializer(DeserializationContext ctx
         }
         JsonDeserializer<?> deserializer;
 
-        /* 19-Mar-2012, tatu: This check used to be done earlier; but we have to defer
-         *   it a bit to collect information on ObjectIdReader, for example.
-         */
         if (type.isAbstract() && !valueInstantiator.canInstantiate()) {
             deserializer = builder.buildAbstract();
         } else {

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

@@ -68,11 +68,12 @@ public String getValueTypeDesc() {
      * be created.
      */
     public boolean canInstantiate() {
-        return canCreateUsingDefault() || canCreateUsingDelegate()
-             || canCreateFromObjectWith() || canCreateFromString()
-             || canCreateFromInt() || canCreateFromLong()
-             || canCreateFromDouble() || canCreateFromBoolean();
-    }    
+        return canCreateUsingDefault()
+                || canCreateUsingDelegate() || canCreateUsingArrayDelegate()
+                || canCreateFromObjectWith() || canCreateFromString()
+                || canCreateFromInt() || canCreateFromLong()
+                || canCreateFromDouble() || canCreateFromBoolean();
+    }
 
     /**
      * Method that can be called to check whether a String-based creator

src/main/java/com/fasterxml/jackson/databind/deser/std/StdValueInstantiator.java

@@ -183,7 +183,7 @@ public String getValueTypeDesc() {
     public Class<?> getValueClass() {
         return _valueClass;
     }
-    
+
     @Override
     public boolean canCreateFromString() {
         return (_fromStringCreator != null);
@@ -208,27 +208,36 @@ public boolean canCreateFromDouble() {
     public boolean canCreateFromBoolean() {
         return (_fromBooleanCreator != null);
     }
-    
+
     @Override
     public boolean canCreateUsingDefault() {
         return (_defaultCreator != null);
     }
 
     @Override
     public boolean canCreateUsingDelegate() {
-        return _delegateType != null;
+        return (_delegateType != null);
     }
 
     @Override
     public boolean canCreateUsingArrayDelegate() {
-        return _arrayDelegateType != null;
+        return (_arrayDelegateType != null);
     }
-    
+
     @Override
     public boolean canCreateFromObjectWith() {
         return (_withArgsCreator != null);
     }
 
+    @Override
+    public boolean canInstantiate() {
+        return canCreateUsingDefault()
+                || canCreateUsingDelegate() || canCreateUsingArrayDelegate()
+                || canCreateFromObjectWith() || canCreateFromString()
+                || canCreateFromInt() || canCreateFromLong()
+                || canCreateFromDouble() || canCreateFromBoolean();
+    }
+
     @Override
     public JavaType getDelegateType(DeserializationConfig config) {
         return _delegateType;
@@ -263,7 +272,7 @@ public Object createUsingDefault(DeserializationContext ctxt) throws IOException
                     null, rewrapCtorProblem(ctxt, t));
         }
     }
-    
+
     @Override
     public Object createFromObjectWith(DeserializationContext ctxt, Object[] args) throws IOException
     {

src/test/java/com/fasterxml/jackson/databind/creators/DelegatingArrayCreator1804Test.java

@@ -0,0 +1,41 @@
+package com.fasterxml.jackson.databind.creators;
+
+import java.util.List;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonValue;
+import com.fasterxml.jackson.databind.BaseMapTest;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class DelegatingArrayCreator1804Test extends BaseMapTest
+{
+    public static class MyTypeImpl extends MyType {
+        private final List<Integer> values;
+
+        MyTypeImpl(List<Integer> values) {
+            this.values = values;
+        }
+
+        @Override
+        public List<Integer> getValues() {
+            return values;
+        }
+    }
+
+    static abstract class MyType {
+        @JsonValue
+        public abstract List<Integer> getValues();
+
+        @JsonCreator(mode=JsonCreator.Mode.DELEGATING)
+        public static MyType of(List<Integer> values) {
+            return new MyTypeImpl(values);
+        }
+    }
+
+
+    public void testDelegatingArray1804() throws Exception {
+        ObjectMapper mapper = new ObjectMapper();
+        MyType thing = mapper.readValue("[]", MyType.class);
+        assertNotNull(thing);
+    }
+}