Merge pull request #1193 from mkokho/fail_on_null_creator_properties

Fail on null creator properties when deserializing

Author: cowtowncoder

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

@@ -230,7 +230,20 @@ public enum DeserializationFeature implements ConfigFeature
      * @since 2.6
      */
     FAIL_ON_MISSING_CREATOR_PROPERTIES(false),
-    
+
+    /**
+      * Feature that determines what happens if one or more Creator properties (properties
+      * bound to parameters of Creator method (constructor or static factory method))
+      * are bound to null values - either from the JSON or as a default value. This
+      * is useful if you want to avoid nulls in your codebase, and particularly useful
+      * if you are using Java or Scala optionals for non-mandatory fields.
+      * Feature is disabled by default, so that no exception is thrown for missing creator
+      * property values, unless they are explicitly marked as `required`.
+      *
+      * @since 2.8
+      */
+    FAIL_ON_NULL_CREATOR_PROPERTIES(false),
+
     /**
      * Feature that determines whether Jackson code should catch
      * and wrap {@link Exception}s (but never {@link Error}s!)

src/main/java/com/fasterxml/jackson/databind/deser/impl/PropertyValueBuffer.java

@@ -125,6 +125,16 @@ protected Object[] getParameters(SettableBeanProperty[] props)
                 }
             }
         }
+
+        if (_context.isEnabled(DeserializationFeature.FAIL_ON_NULL_CREATOR_PROPERTIES)) {
+            for (int ix = 0; ix < props.length; ++ix) {
+              if (_creatorParameters[ix] == null) {
+                  throw _context.mappingException("Null value for creator property '%s'; DeserializationFeature.FAIL_ON_NULL_FOR_CREATOR_PARAMETERS enabled",
+                          props[ix].getName(), props[ix].getCreatorIndex());
+              }
+            }
+        }
+
         return _creatorParameters;
     }
 

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

@@ -0,0 +1,60 @@
+package com.fasterxml.jackson.databind.creators;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.*;
+
+/**
+ * Tests to ensure that deserialization fails when a bean property has a null value
+ * Relates to <a href="https://github.com/FasterXML/jackson-databind/issues/988">issue #988</a>
+ */
+public class FailOnNullCreatorTest extends BaseMapTest
+{
+    static class Person {
+        String name;
+        Integer age;
+
+        @JsonCreator
+        public Person(@JsonProperty(value="name") String name,
+                      @JsonProperty(value="age") int age)
+        {
+            this.name = name;
+            this.age = age;
+        }
+    }
+
+    private final ObjectReader POINT_READER = objectMapper().readerFor(Person.class);
+
+    public void testRequiredNonNullParam() throws Exception
+    {
+        Person p;
+        // First: fine if feature is not enabled
+        p = POINT_READER.readValue(aposToQuotes("{}"));
+        assertEquals(null, p.name);
+        assertEquals(Integer.valueOf(0), p.age);
+
+        // Second: fine if feature is enabled but default value is not null
+        ObjectReader r = POINT_READER.with(DeserializationFeature.FAIL_ON_NULL_CREATOR_PROPERTIES);
+        p = POINT_READER.readValue(aposToQuotes("{'name':'John', 'age': null}"));
+        assertEquals("John", p.name);
+        assertEquals(Integer.valueOf(0), p.age);
+
+        // Third: throws exception if property is missing
+        try {
+            r.readValue(aposToQuotes("{}"));
+            fail("Should not pass third test");
+        } catch (JsonMappingException e) {
+            verifyException(e, "Null value for creator property 'name'");
+        }
+
+        // Fourth: throws exception if property is set to null explicitly
+        try {
+            r.readValue(aposToQuotes("{'age': 5, 'name': null}"));
+            fail("Should not pass fourth test");
+        } catch (JsonMappingException e) {
+            verifyException(e, "Null value for creator property 'name'");
+        }
+    }
+
+
+}