Deprecated AbstractMapper, made empty objects and arrays shorter, actually respecting the transient keyword, omitting null fields by default and added options to disable this feature

Author: JanHolger

src/main/java/org/javawebstack/abstractdata/AbstractMapper.java

@@ -2,31 +2,39 @@
 
 import org.javawebstack.abstractdata.mapper.Mapper;
 
+@Deprecated
 public class AbstractMapper {
 
     private final Mapper mapper = new Mapper();
     private NamingPolicy namingPolicy = NamingPolicy.NONE;
     private String dateFormat = "yyyy-MM-dd HH:mm:ss";
-    private boolean exposeRequired = false;
 
     public AbstractMapper setNamingPolicy(NamingPolicy namingPolicy) {
         this.namingPolicy = namingPolicy;
         mapper.namingPolicy(namingPolicy.getMapperPolicy());
         return this;
     }
 
+    public boolean shouldOmitNull() {
+        return mapper.shouldOmitNull();
+    }
+
+    public AbstractMapper setOmitNull(boolean omitNull) {
+        this.mapper.omitNull(omitNull);
+        return this;
+    }
+
     public NamingPolicy getNamingPolicy() {
         return namingPolicy;
     }
 
     public AbstractMapper setExposeRequired(boolean exposeRequired) {
-        this.exposeRequired = exposeRequired;
         mapper.requireExpose(exposeRequired);
         return this;
     }
 
     public boolean isExposeRequired() {
-        return exposeRequired;
+        return mapper.isExposeRequired();
     }
 
     public AbstractMapper setDateFormat(String dateFormat) {

src/main/java/org/javawebstack/abstractdata/json/JsonDumper.java

@@ -39,6 +39,10 @@ private List<String> dumpLines(AbstractElement element) {
             return Collections.singletonList("\"" + escape(element.string()) + "\"");
         if(element.isObject()) {
             List<String> lines =new ArrayList<>();
+            if(element.object().size() == 0) {
+                lines.add("{}");
+                return lines;
+            }
             if(pretty) {
                 lines.add("{");
                 List<String> keys = new ArrayList<>(element.object().keys());
@@ -59,6 +63,10 @@ private List<String> dumpLines(AbstractElement element) {
         }
         if(element.isArray()) {
             List<String> lines =new ArrayList<>();
+            if(element.array().size() == 0) {
+                lines.add("[]");
+                return lines;
+            }
             if(pretty) {
                 lines.add("[");
                 AbstractArray array = element.array();

src/main/java/org/javawebstack/abstractdata/mapper/DefaultMappers.java

@@ -276,7 +276,10 @@ public AbstractElement toAbstract(MapperContext context, Object value) throws Ma
                     if(context.getMapper().isExposeRequired() ? !fs.isExpose() : fs.isHidden())
                         continue;
                     String k = fs.getName() != null ? fs.getName() : context.getMapper().getNamingPolicy().toAbstract(fs.getField().getName());
-                    object.set(k, context.getMapper().map(new MapperContext(context.getMapper(), fs.getField(), fs.getAnnotations()).adapter(fs.getAdapter()), fs.getField().get(value)));
+                    AbstractElement e = context.getMapper().map(new MapperContext(context.getMapper(), fs.getField(), fs.getAnnotations()).adapter(fs.getAdapter()), fs.getField().get(value));
+                    if(e.isNull() && context.getMapper().shouldOmitNull() && fs.shouldOmitNull())
+                        continue;
+                    object.set(k, e);
                 }
                 if(spec.getAdditionalField() != null) {
                     AbstractObject additional = (AbstractObject) spec.getAdditionalField().get(value);

src/main/java/org/javawebstack/abstractdata/mapper/Mapper.java

@@ -20,6 +20,7 @@ public class Mapper {
     private DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
     private NamingPolicy namingPolicy = NamingPolicy.NONE;
     private boolean exposeRequired;
+    private boolean omitNull = true;
     private final Map<Class<?>, MapperTypeAdapter> adapters = DefaultMappers.create();
     private final MapperContext emptyContext = new MapperContext(this, null, new HashMap<>());
 
@@ -74,6 +75,15 @@ public DateFormat getDateFormat() {
         return dateFormat;
     }
 
+    public boolean shouldOmitNull() {
+        return omitNull;
+    }
+
+    public Mapper omitNull(boolean omitNull) {
+        this.omitNull = omitNull;
+        return this;
+    }
+
     public Mapper namingPolicy(NamingPolicy namingPolicy) {
         this.namingPolicy = namingPolicy;
         return this;

src/main/java/org/javawebstack/abstractdata/mapper/MapperTypeSpec.java

@@ -86,8 +86,10 @@ private void checkoutField(Field field) throws MapperException {
             }
             spec.order = options.order();
             spec.expose = options.expose();
-            spec.hidden = options.hidden() || Modifier.isTransient(field.getModifiers());
+            spec.hidden = options.hidden();
+            spec.omitNull = options.omitNull();
         }
+        spec.hidden = spec.hidden || Modifier.isTransient(field.getModifiers());
     }
 
     public Class<?> getType() {
@@ -111,6 +113,7 @@ public static class FieldSpec {
         private int order;
         private boolean expose;
         private boolean hidden;
+        private boolean omitNull = true;
         private MapperTypeAdapter adapter;
         private Map<Class<? extends Annotation>, List<Annotation>> annotations = new HashMap<>();
 
@@ -135,6 +138,10 @@ public boolean isHidden() {
             return hidden;
         }
 
+        public boolean shouldOmitNull() {
+            return omitNull;
+        }
+
         public MapperTypeAdapter getAdapter() {
             return adapter;
         }

src/main/java/org/javawebstack/abstractdata/mapper/annotation/MapperOptions.java

@@ -16,6 +16,7 @@
     Class<?>[] generic() default {};
     boolean expose() default false;
     boolean hidden() default false;
+    boolean omitNull() default true;
     Class<? extends MapperTypeAdapter> adapter() default MapperTypeAdapter.class;
 
 }