support json property methods

Author: SentryMan

jsonb-generator/src/main/java/io/avaje/jsonb/generator/FieldReader.java

@@ -1,6 +1,7 @@
 package io.avaje.jsonb.generator;
 
 import javax.lang.model.element.Element;
+import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.Modifier;
 import java.util.*;
 
@@ -24,18 +25,23 @@ final class FieldReader {
     addSubType(subType);
     final PropertyIgnoreReader ignoreReader = new PropertyIgnoreReader(element);
     this.unmapped = ignoreReader.unmapped();
+    var isMethod = element instanceof ExecutableElement;
     this.raw = ignoreReader.raw();
     this.serialize = ignoreReader.serialize();
-    this.deserialize = ignoreReader.deserialize();
+    this.deserialize = !isMethod && ignoreReader.deserialize();
 
     final var fieldName = element.getSimpleName().toString();
-    final var publicField = element.getModifiers().contains(Modifier.PUBLIC);
-    this.property = new FieldProperty(element.asType(), raw, unmapped, genericTypeParams, publicField, fieldName);
+    final var publicField = !isMethod && element.getModifiers().contains(Modifier.PUBLIC);
+
+    var type = isMethod ? ((ExecutableElement) element).getReturnType() : element.asType();
+
+    this.property =
+        new FieldProperty(type, raw, unmapped, genericTypeParams, publicField, fieldName);
     this.propertyName =
-      PropertyPrism.getOptionalOn(element)
-        .map(PropertyPrism::value)
-        .map(Util::escapeQuotes)
-        .orElse(namingConvention.from(fieldName));
+        PropertyPrism.getOptionalOn(element)
+            .map(PropertyPrism::value)
+            .map(Util::escapeQuotes)
+            .orElse(namingConvention.from(fieldName));
 
     this.aliases = initAliases(element);
   }

jsonb-generator/src/main/java/io/avaje/jsonb/generator/TypeReader.java

@@ -94,7 +94,7 @@ void read(TypeElement type) {
           readField(element, localFields);
           break;
         case METHOD:
-          readMethod(element, type);
+          readMethod(element, type, localFields);
           break;
       }
     }
@@ -169,7 +169,7 @@ private void readConstructor(Element element, TypeElement type) {
     }
   }
 
-  private void readMethod(Element element, TypeElement type) {
+  private void readMethod(Element element, TypeElement type, List<FieldReader> localFields) {
     ExecutableElement methodElement = (ExecutableElement) element;
     if (checkMethod2(methodElement)) {
       List<? extends VariableElement> parameters = methodElement.getParameters();
@@ -186,6 +186,24 @@ private void readMethod(Element element, TypeElement type) {
         }
       }
     }
+    // for reading methods
+    PropertyPrism.getOptionalOn(methodElement)
+        .ifPresent(
+            p -> {
+              if (!methodElement.getParameters().isEmpty()) {
+                logError("Json.Property can only be placed on Getter Methods", methodElement);
+                return;
+              }
+
+              final var frequency =
+                  frequencyMap.compute(p.value(), (k, v) -> v == null ? 0 : v + 1);
+
+              final var reader =
+                  new FieldReader(
+                      element, namingConvention, currentSubType, genericTypeParams, frequency);
+              localFields.add(reader);
+              reader.getterMethod(new MethodReader(methodElement, type));
+            });
   }
 
   private boolean checkMethod2(ExecutableElement methodElement) {

jsonb-generator/src/test/java/io/avaje/jsonb/generator/models/valid/TestClass.java

@@ -25,6 +25,11 @@ public class TestClass {
 
   private Optional<String> op;
 
+  @Json.Property("what_a_save!")
+  public String what_a_save() {
+    return "Chat Disabled";
+  }
+
   public String getAlias() {
     return alias;
   }

jsonb/src/main/java/io/avaje/jsonb/Json.java

@@ -110,7 +110,7 @@
    * }</pre>
    */
   @Retention(CLASS)
-  @Target(FIELD)
+  @Target({FIELD, METHOD})
   @interface Property {
 
     /**
@@ -138,7 +138,7 @@
   }
 
   /**
-   * Deprecate - migrate to {@link Json.Alias}.
+   * Deprecated - migrate to {@link Json.Alias}.
    */
   @Deprecated
   @Retention(CLASS)
@@ -188,7 +188,7 @@
    * }</pre>
    */
   @Retention(CLASS)
-  @Target(FIELD)
+  @Target({FIELD, METHOD})
   @interface Unmapped {
 
   }
@@ -278,7 +278,7 @@
    * Marks a String field as containing raw JSON content.
    */
   @Retention(CLASS)
-  @Target(FIELD)
+  @Target({FIELD, METHOD})
   @interface Raw {
 
   }