Issue #1313: New IgnoreCase feature to deserialize enums

src/main/java/com/fasterxml/jackson/databind/DeserializationFeature.java

@@ -106,6 +106,14 @@ public enum DeserializationFeature implements ConfigFeature
      */
     READ_ENUMS_USING_TO_STRING(false),
 
+    /**
+     * Feature that determines if Enum deserialization should be case sensitive or not.
+     * If enabled, Enum deserialization will ignore case.
+     * <p>
+     * Feature is disabled by default.
+     */
+    READ_ENUMS_IGNORING_CASE(false),
+
     /*
     /******************************************************
      *  Error handling features

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

@@ -167,6 +167,13 @@ private final Object _deserializeAltString(JsonParser p, DeserializationContext
             if (ctxt.isEnabled(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT)) {
                 return null;
             }
+        } else if (ctxt.isEnabled(DeserializationFeature.READ_ENUMS_IGNORING_CASE)) {
+            // [databind#1313]: Case insensitive enum deserialization
+            for (String key : lookup.keys()) {
+                if (key.equalsIgnoreCase(name)) {
+                    return lookup.find(key);
+                }
+            }
         } else if (!ctxt.isEnabled(DeserializationFeature.FAIL_ON_NUMBERS_FOR_ENUMS)) {
             // [databind#149]: Allow use of 'String' indexes as well -- unless prohibited (as per above)
             char c = name.charAt(0);

src/test/java/com/fasterxml/jackson/databind/deser/EnumDeserializationTest.java

@@ -11,6 +11,7 @@
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.fasterxml.jackson.databind.deser.std.FromStringDeserializer;
 import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
+import com.fasterxml.jackson.databind.exc.InvalidFormatException;
 import com.fasterxml.jackson.databind.module.SimpleModule;
 
 @SuppressWarnings("serial")
@@ -510,4 +511,56 @@ public void testExceptionFromCustomEnumKeyDeserializer() {
             assertTrue(e.getMessage().contains("Undefined AnEnum"));
         }
     }
+
+    public void testFailWhenCaseSensitiveAndNameIsNotUpperCase() throws IOException {
+        ObjectMapper objectMapper = new ObjectMapper();
+
+        try {
+            objectMapper.readValue("\"Jackson\"", TestEnum.class);
+            fail("InvalidFormatException expected");
+        } catch (InvalidFormatException e) {
+            assertTrue(e.getMessage().contains("value not one of declared Enum instance names: [JACKSON, OK, RULES]"));
+        }
+    }
+
+    public void testFailWhenCaseSensitiveAndToStringIsUpperCase() throws IOException {
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.enable(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
+
+        try {
+            objectMapper.readValue("\"A\"", LowerCaseEnum.class);
+            fail("InvalidFormatException expected");
+        } catch (InvalidFormatException e) {
+            assertTrue(e.getMessage().contains("value not one of declared Enum instance names: [a, b, c]"));
+        }
+    }
+
+    public void testEnumDesIgnoringCaseWithLowerCaseContent() throws IOException {
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.enable(DeserializationFeature.READ_ENUMS_IGNORING_CASE);
+
+        TestEnum testEnum = objectMapper.readValue("\"jackson\"", TestEnum.class);
+
+        assertEquals(TestEnum.JACKSON, testEnum);
+    }
+
+    public void testEnumDesIgnoringCaseWithUpperCaseToString() throws IOException {
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.enable(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
+        objectMapper.enable(DeserializationFeature.READ_ENUMS_IGNORING_CASE);
+
+        LowerCaseEnum lowerCaseEnum = objectMapper.readValue("\"A\"", LowerCaseEnum.class);
+
+        assertEquals(LowerCaseEnum.A, lowerCaseEnum);
+    }
+
+    public void testIgnoreCaseInEnumList() throws Exception {
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.enable(DeserializationFeature.READ_ENUMS_IGNORING_CASE);
+
+        TestEnum[] testEnum = objectMapper.readValue("[\"jackson\", \"rules\"]", TestEnum[].class);
+
+        assertEquals(TestEnum.JACKSON, testEnum[0]);
+        assertEquals(TestEnum.RULES, testEnum[1]);
+    }
 }