Added feature to allow deserialization of unknown Enums using a prede…

…fined value.
FasterXML · Feb 12, 2016 · a0f36f3 · a0f36f3
1 parent 5235ba8
commit a0f36f3
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Showing 4 changed files with 108 additions and 5 deletions.
diff --git a/src/main/java/com/fasterxml/jackson/databind/DeserializationFeature.java b/src/main/java/com/fasterxml/jackson/databind/DeserializationFeature.java
@@ -353,6 +353,18 @@ public enum DeserializationFeature implements ConfigFeature
      */
     READ_UNKNOWN_ENUM_VALUES_AS_NULL(false),
 
+    /**
+     * Feature that allows unknown Enum values to be ignored and a predefined value specified through
+     * {@link com.fasterxml.jackson.annotation.JsonEnumDefaultValue @JsonEnumDefaultValue} annotation.
+     * If disabled, unknown Enum values will throw exceptions.
+     * If enabled, but no predefined default Enum value is specified, an exception will be thrown as well.
+     *<p>
+     * Feature is disabled by default.
+     *
+     * @since 2.8
+     */
+    READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE(false),
+
     /**
      * Feature that controls whether numeric timestamp values are expected
      * to be written using nanosecond timestamps (enabled) or not (disabled),

diff --git a/src/main/java/com/fasterxml/jackson/databind/deser/std/EnumDeserializer.java b/src/main/java/com/fasterxml/jackson/databind/deser/std/EnumDeserializer.java
@@ -28,6 +28,7 @@ public class EnumDeserializer
      * @since 2.6
      */
     protected final CompactStringObjectMap _enumLookup;
+    private final Enum<?> _enumDefaultValue;
 
     /**
      * @since 2.6
@@ -39,6 +40,7 @@ public EnumDeserializer(EnumResolver res)
         super(res.getEnumClass());
         _enumLookup = res.constructLookup();
         _enumsByIndex = res.getRawEnums();
+        _enumDefaultValue = res.getDefaultValue();
     }
 
     /**
@@ -97,6 +99,9 @@ public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOEx
             if (index >= 0 && index <= _enumsByIndex.length) {
                 return _enumsByIndex[index];
             }
+            if (ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE) && _enumDefaultValue != null) {
+                return _enumDefaultValue;
+            }
             if (!ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)) {
                 throw ctxt.weirdNumberException(index, _enumClass(),
                         "index value outside legal index range [0.."+(_enumsByIndex.length-1)+"]");
@@ -131,6 +136,10 @@ private final Object _deserializeAltString(JsonParser p, DeserializationContext
                 }
             }
         }
+        if (ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE)
+            && _enumDefaultValue != null) {
+            return _enumDefaultValue;
+        }
         if (!ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)) {
             throw ctxt.weirdStringException(name, _enumClass(),
                     "value not one of declared Enum instance names: "+_enumLookup.keys());

diff --git a/src/main/java/com/fasterxml/jackson/databind/util/EnumResolver.java b/src/main/java/com/fasterxml/jackson/databind/util/EnumResolver.java
@@ -1,7 +1,11 @@
 package com.fasterxml.jackson.databind.util;
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue;
+import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.databind.AnnotationIntrospector;
 
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.*;
 
@@ -19,11 +23,14 @@ public class EnumResolver implements java.io.Serializable
 
     protected final HashMap<String, Enum<?>> _enumsById;
 
-    protected EnumResolver(Class<Enum<?>> enumClass, Enum<?>[] enums, HashMap<String, Enum<?>> map)
+    protected final Enum<?> _defaultValue;
+
+    protected EnumResolver(Class<Enum<?>> enumClass, Enum<?>[] enums, HashMap<String, Enum<?>> map, Enum<?> defaultValue)
     {
         _enumClass = enumClass;
         _enums = enums;
         _enumsById = map;
+        _defaultValue = defaultValue;
     }
 
     /**
@@ -45,7 +52,29 @@ public static EnumResolver constructFor(Class<Enum<?>> enumCls, AnnotationIntros
             }
             map.put(name, enumValues[i]);
         }
-        return new EnumResolver(enumCls, enumValues, map);
+
+        Enum<?> defaultEnum = determineDefaultEnumValue(enumCls);
+
+        return new EnumResolver(enumCls, enumValues, map, defaultEnum);
+    }
+
+    private static Enum<?> determineDefaultEnumValue(Class<Enum<?>> enumCls) {
+        Field[] fields = ClassUtil.getDeclaredFields(enumCls);
+        for (Field field : fields) {
+            JsonEnumDefaultValue defaultValueAnnotation = field.getAnnotation(JsonEnumDefaultValue.class);
+            if (defaultValueAnnotation != null && field.isEnumConstant()) {
+                try {
+                    Method valueOf = enumCls.getDeclaredMethod("valueOf", String.class);    // using `getMethod` causes IllegalAccessException
+                    valueOf.setAccessible(true);
+                    return enumCls.cast(valueOf.invoke(null, field.getName()));
+                } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
+                    java.util.logging.Logger.getLogger(EnumResolver.class.getName())
+                        .warning("Could not extract Enum annotated with " + JsonEnumDefaultValue.class.getSimpleName()
+                            + " due to: " + e.getLocalizedMessage());
+                }
+            }
+        }
+        return null;
     }
 
     /**
@@ -61,7 +90,8 @@ public static EnumResolver constructUsingToString(Class<Enum<?>> enumCls)
             Enum<?> e = enumValues[i];
             map.put(e.toString(), e);
         }
-        return new EnumResolver(enumCls, enumValues, map);
+        Enum<?> defaultValue = determineDefaultEnumValue(enumCls);
+        return new EnumResolver(enumCls, enumValues, map, defaultValue);
     }    
 
     public static EnumResolver constructUsingMethod(Class<Enum<?>> enumCls,
@@ -81,7 +111,10 @@ public static EnumResolver constructUsingMethod(Class<Enum<?>> enumCls,
                 throw new IllegalArgumentException("Failed to access @JsonValue of Enum value "+en+": "+e.getMessage());
             }
         }
-        return new EnumResolver(enumCls, enumValues, map);
+
+        Enum<?> defaultValue = determineDefaultEnumValue(enumCls);
+
+        return new EnumResolver(enumCls, enumValues, map, defaultValue);
     }    
 
     /**
@@ -125,7 +158,7 @@ public static EnumResolver constructUnsafeUsingMethod(Class<?> rawEnumCls, Metho
     public CompactStringObjectMap constructLookup() {
         return CompactStringObjectMap.construct(_enumsById);
     }
-    
+
     public Enum<?> findEnum(String key) { return _enumsById.get(key); }
 
     public Enum<?> getEnum(int index) {
@@ -135,6 +168,10 @@ public Enum<?> getEnum(int index) {
         return _enums[index];
     }
 
+    public Enum<?> getDefaultValue(){
+        return _defaultValue;
+    }
+
     public Enum<?>[] getRawEnums() {
         return _enums;
     }

diff --git a/src/test/java/com/fasterxml/jackson/databind/deser/TestEnumDeserialization.java b/src/test/java/com/fasterxml/jackson/databind/deser/TestEnumDeserialization.java
@@ -167,6 +167,27 @@ public String toString() {
         ;
     }
 
+    static enum EnumWithDefaultAnno {
+        A, B,
+
+        @JsonEnumDefaultValue
+        OTHER;
+    }
+
+    static enum EnumWithDefaultAnnoAndConstructor {
+        A, B,
+
+        @JsonEnumDefaultValue
+        OTHER;
+
+        @JsonCreator public static EnumWithDefaultAnnoAndConstructor fromId(String value) {
+            for (EnumWithDefaultAnnoAndConstructor e: values()) {
+                if (e.name().toLowerCase().equals(value)) return e;
+            }
+            return null;
+        }
+    }
+
     /*
     /**********************************************************
     /* Tests
@@ -481,4 +502,28 @@ public void testEnumWithJsonPropertyRename() throws Exception
         assertSame(EnumWithPropertyAnno.B, result[0]);
         assertSame(EnumWithPropertyAnno.A, result[1]);
     }
+
+    public void testEnumWithDefaultAnnotation() throws Exception {
+        final ObjectMapper mapper = new ObjectMapper();
+        mapper.enable(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE);
+
+        EnumWithDefaultAnno myEnum = mapper.readValue("\"foo\"", EnumWithDefaultAnno.class);
+        assertSame(EnumWithDefaultAnno.OTHER, myEnum);
+    }
+
+    public void testEnumWithDefaultAnnotationUsingIndexes() throws Exception {
+        final ObjectMapper mapper = new ObjectMapper();
+        mapper.enable(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE);
+
+        EnumWithDefaultAnno myEnum = mapper.readValue("9", EnumWithDefaultAnno.class);
+        assertSame(EnumWithDefaultAnno.OTHER, myEnum);
+    }
+
+    public void testEnumWithDefaultAnnotationWithConstructor() throws Exception {
+        final ObjectMapper mapper = new ObjectMapper();
+        mapper.enable(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE);
+
+        EnumWithDefaultAnnoAndConstructor myEnum = mapper.readValue("\"foo\"", EnumWithDefaultAnnoAndConstructor.class);
+        assertNull("When using a constructor, the default value annotation shouldn't be used.", myEnum);
+    }
 }