Error serializing multiple JSON fields named 'map' with Gson (#1070)

* GAM: fix for the error: Class com.genexus.json.JSONObjectWrapper declares multiple JSON fields named 'map'; conflict is caused by fields com.genexus.json.JSONObjectWrapper#map and org.json.JSONObject#map

* GAM: do not print the decimal point if it is a whole number

* GAM: serialize null values

* GAM: fix for multiple JSON fields named 'map'

Author: mrodbratschi

gamutils/src/main/java/com/genexus/gam/utils/Dictionary.java

@@ -1,14 +1,12 @@
 package com.genexus.gam.utils;
 
 import com.genexus.GxUserType;
-import com.google.gson.Gson;
-import com.google.gson.GsonBuilder;
-import com.google.gson.JsonParser;
-import com.google.gson.JsonElement;
-import com.google.gson.JsonPrimitive;
-import com.google.gson.JsonSyntaxException;
+import com.google.gson.*;
 import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
 
+import java.io.IOException;
 import java.lang.reflect.Type;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -23,7 +21,42 @@ public class Dictionary {
 
 	public Dictionary() {
 		this.userMap = new LinkedHashMap<>();
-		this.gson = new GsonBuilder().serializeNulls().create();
+		this.gson = new GsonBuilder().serializeNulls()
+			.addSerializationExclusionStrategy(new ExclusionStrategy() {
+				@Override
+				public boolean shouldSkipField(FieldAttributes f) {
+					// exclude only the field 'map' inherited from org.json.JSONObject
+					return f.getName().equals("map") &&
+						f.getDeclaringClass() == org.json.JSONObject.class;
+				}
+
+				@Override
+				public boolean shouldSkipClass(Class<?> clazz) {
+					return false;
+				}
+			})
+			.registerTypeHierarchyAdapter(Number.class, new TypeAdapter<Number>() {
+				@Override
+				public void write(JsonWriter out, Number value) throws IOException {
+					if (value == null) {
+						out.nullValue();
+						return;
+					}
+
+					double d = value.doubleValue();
+					if (d == Math.rint(d)) {
+						out.value(value.longValue()); // 1.0 → 1
+					} else {
+						out.value(d);                 // 1.5 → 1.5
+					}
+				}
+
+				@Override
+				public Number read(JsonReader in) throws IOException {
+					return in.nextDouble();
+				}
+			})
+			.create();
 	}
 
 	public Object get(String key) {
@@ -54,40 +87,59 @@ private Map<String, Object> jsonStringToMap(String jsonString) {
 		return this.gson.fromJson(jsonString, type);
 	}
 
-	private void objectToMap(String key, Object value) {
-		if (value == null) {
-			this.userMap.put(key, null);
-		} else if (value instanceof Number || value instanceof Boolean || value instanceof Map || value instanceof List) {
-			this.userMap.put(key, value);
-		} else if (value instanceof GxUserType) {
-			this.userMap.put(key, jsonStringToMap(((GxUserType) value).toJSonString()));
-		} else if (value instanceof String) {
-			String str = (String) value;
-
-			// Try to parse as JSON
+	private Object deepConvert(Object value) {
+		if (value == null) return null;
+
+		if (value instanceof Number || value instanceof Boolean) {
+			return value;
+		}
+
+		if (value instanceof String) {
 			try {
-				JsonElement parsed = JsonParser.parseString(str);
+				JsonElement parsed = JsonParser.parseString((String) value);
 				if (parsed.isJsonObject()) {
-					this.userMap.put(key, this.gson.fromJson(parsed, Map.class));
-				} else if (parsed.isJsonArray()) {
-					this.userMap.put(key, this.gson.fromJson(parsed, List.class));
-				} else if (parsed.isJsonPrimitive()) {
-					JsonPrimitive primitive = parsed.getAsJsonPrimitive();
-					if (primitive.isBoolean()) {
-						this.userMap.put(key, primitive.getAsBoolean());
-					} else if (primitive.isNumber()) {
-						this.userMap.put(key, primitive.getAsNumber());
-					} else if (primitive.isString()) {
-						this.userMap.put(key, primitive.getAsString());
-					}
+					return gson.fromJson(parsed, Map.class);
 				}
-			} catch (JsonSyntaxException e) {
-				// Invalid JSON: it is left as string
-				this.userMap.put(key, str);
+				if (parsed.isJsonArray()) {
+					return gson.fromJson(parsed, List.class);
+				}
+				return ((JsonPrimitive) parsed).getAsString();
+			} catch (Exception e) {
+				return value;
 			}
-		} else {
-			// Any other object: it is converted to string
-			this.userMap.put(key, value.toString());
 		}
+
+		// SDT => Map
+		if (value instanceof GxUserType) {
+			String s = ((GxUserType) value).toJSonString();
+			return jsonStringToMap(s);
+		}
+
+		// Map => deep convert values
+		if (value instanceof Map) {
+			Map<String,Object> newMap = new LinkedHashMap<>();
+			((Map<?,?>) value).forEach((k,v) -> newMap.put(k.toString(), deepConvert(v)));
+			return newMap;
+		}
+
+		// List => deep convert each element
+		if (value instanceof List) {
+			List<Object> newList = new java.util.ArrayList<>();
+			for (Object o : (List<?>) value) newList.add(deepConvert(o));
+			return newList;
+		}
+
+		// Catch: JSONObjectWrapper
+		if (value.getClass().getName().contains("JSONObjectWrapper") ||
+			value instanceof org.json.JSONObject) {
+			// Convert org.json to Map
+			return jsonStringToMap(value.toString());
+		}
+
+		return value.toString();
+	}
+
+	private void objectToMap(String key, Object value) {
+		this.userMap.put(key, deepConvert(value));
 	}
 }