FasterXML/jackson-databind#1296 @JsonIncludeProperties (#174)

Add `@JsonIncludeProperties`

Author: sp4ce

src/main/java/com/fasterxml/jackson/annotation/JsonIncludeProperties.java

@@ -0,0 +1,167 @@
+package com.fasterxml.jackson.annotation;
+
+import com.fasterxml.jackson.annotation.JsonInclude.Include;
+
+import javax.swing.text.html.HTMLDocument;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Set;
+
+/**
+ * Annotation that can be used to either only include serialization of
+ * properties (during serialization), or only include processing of
+ * JSON properties read (during deserialization).
+ * <p>
+ * Example:
+ * <pre>
+ * // to only include specified fields from being serialized or deserialized
+ * // (i.e. only include in JSON output; or being set even if they were included)
+ * &#064;JsonIncludeProperties({ "internalId", "secretKey" })
+ * </pre>
+ * <p>
+ * Annotation can be applied both to classes and
+ * to properties. If used for both, actual set will be union of all
+ * includes: that is, you can only add properties to include, not remove
+ * or override. So you can not remove properties to include using
+ * per-property annotation.
+ *
+ * @since 2.12
+ */
+@Target({ElementType.ANNOTATION_TYPE, ElementType.TYPE,
+        ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.FIELD})
+@Retention(RetentionPolicy.RUNTIME)
+@JacksonAnnotation
+public @interface JsonIncludeProperties
+{
+    /**
+     * Names of properties to include.
+     */
+    public String[] value() default {};
+
+    /*
+    /**********************************************************
+    /* Value class used to enclose information, allow for
+    /* merging of layered configuration settings.
+    /**********************************************************
+     */
+
+    /**
+     * Helper class used to contain information from a single {@link JsonIncludeProperties}
+     * annotation, as well as to provide possible overrides from non-annotation sources.
+     *
+     * @since 2.12
+     */
+    public static class Value implements JacksonAnnotationValue<JsonIncludeProperties>, java.io.Serializable
+    {
+        private static final long serialVersionUID = 1L;
+
+        /**
+         * Default instance has no explicitly included fields
+         */
+        protected final static JsonIncludeProperties.Value ALL = new JsonIncludeProperties.Value(null);
+
+        /**
+         * Name of the properties to include.
+         * Null means that all properties are included, empty means none.
+         */
+        protected final Set<String> _included;
+
+        protected Value(Set<String> included)
+        {
+            _included = included;
+        }
+
+        public static JsonIncludeProperties.Value from(JsonIncludeProperties src)
+        {
+            if (src == null) {
+                return ALL;
+            }
+
+            return new Value(_asSet(src.value()));
+        }
+
+        public static JsonIncludeProperties.Value all()
+        {
+            return ALL;
+        }
+
+        @Override
+        public Class<JsonIncludeProperties> valueFor()
+        {
+            return JsonIncludeProperties.class;
+        }
+
+        public Set<String> getIncluded()
+        {
+            return _included;
+        }
+
+        /**
+         * Mutant factory method to override the current value with an another, merging the included fields.
+         */
+        public JsonIncludeProperties.Value withOverrides(JsonIncludeProperties.Value overrides) {
+            if (overrides == null || overrides.getIncluded() == null) {
+                return this;
+            }
+
+            if (_included == null) {
+                return overrides;
+            }
+
+            HashSet<String> included = new HashSet<String>(_included);
+            Iterator<String> iterator = included.iterator();
+            while (iterator.hasNext()) {
+                if (!overrides.getIncluded().contains(iterator.next())) {
+                    iterator.remove();
+                }
+            }
+
+            return new JsonIncludeProperties.Value(new HashSet<String>(included));
+        }
+
+        @Override
+        public String toString() {
+            return String.format("JsonIncludeProperties.Value(included=%s)",
+                    _included);
+        }
+
+        @Override
+        public int hashCode() {
+            return (_included == null ? 0 : _included.size())
+                    ;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (o == this) return true;
+            if (o == null) return false;
+            return (o.getClass() == getClass())
+                    && _equals(this, (Value) o);
+        }
+
+        private static boolean _equals(Value a, Value b)
+        {
+            return  a._included == null ? b._included == null :
+                    // keep this last just because it can be expensive
+                    a._included.equals(b._included)
+                    ;
+        }
+
+        private static Set<String> _asSet(String[] v)
+        {
+            if (v == null || v.length == 0) {
+                return Collections.emptySet();
+            }
+            Set<String> s = new HashSet<String>(v.length);
+            for (String str : v) {
+                s.add(str);
+            }
+            return s;
+        }
+    }
+}

src/test/java/com/fasterxml/jackson/annotation/JsonIncludePropertiesTest.java

@@ -0,0 +1,68 @@
+package com.fasterxml.jackson.annotation;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+/**
+ * Tests to verify that it is possibly to merge {@link JsonIncludeProperties.Value}
+ * instances for overrides
+ */
+public class JsonIncludePropertiesTest extends TestBase
+{
+    @JsonIncludeProperties(value = {"foo", "bar"})
+    private final static class Bogus
+    {
+    }
+
+    private final JsonIncludeProperties.Value ALL = JsonIncludeProperties.Value.all();
+
+    public void testAll()
+    {
+        assertSame(ALL, JsonIncludeProperties.Value.from(null));
+        assertNull(ALL.getIncluded());
+        assertEquals(ALL, ALL);
+        assertEquals("JsonIncludeProperties.Value(included=null)", ALL.toString());
+        assertEquals(0, ALL.hashCode());
+    }
+
+    public void testFromAnnotation()
+    {
+        JsonIncludeProperties.Value v = JsonIncludeProperties.Value.from(Bogus.class.getAnnotation(JsonIncludeProperties.class));
+        assertNotNull(v);
+        Set<String> included = v.getIncluded();
+        assertEquals(2, v.getIncluded().size());
+        assertEquals(_set("foo", "bar"), included);
+        assertEquals("JsonIncludeProperties.Value(included=[bar, foo])", v.toString());
+        assertEquals(v, JsonIncludeProperties.Value.from(Bogus.class.getAnnotation(JsonIncludeProperties.class)));
+    }
+
+    public void testWithOverridesAll() {
+        JsonIncludeProperties.Value v = JsonIncludeProperties.Value.from(Bogus.class.getAnnotation(JsonIncludeProperties.class));
+        v = v.withOverrides(ALL);
+        Set<String> included = v.getIncluded();
+        assertEquals(2, included.size());
+        assertEquals(_set("foo", "bar"), included);
+    }
+
+    public void testWithOverridesEmpty() {
+        JsonIncludeProperties.Value v = JsonIncludeProperties.Value.from(Bogus.class.getAnnotation(JsonIncludeProperties.class));
+        v = v.withOverrides(new JsonIncludeProperties.Value(Collections.<String>emptySet()));
+        Set<String> included = v.getIncluded();
+        assertEquals(0, included.size());
+    }
+
+    public void testWithOverridesMerge() {
+        JsonIncludeProperties.Value v = JsonIncludeProperties.Value.from(Bogus.class.getAnnotation(JsonIncludeProperties.class));
+        v = v.withOverrides(new JsonIncludeProperties.Value(_set("foo")));
+        Set<String> included = v.getIncluded();
+        assertEquals(1, included.size());
+        assertEquals(_set("foo"), included);
+    }
+
+    private Set<String> _set(String... args)
+    {
+        return new LinkedHashSet<String>(Arrays.asList(args));
+    }
+}