Add validator debugger where the wrong type is returned

2 files changed, 42 insertions, 1 deletions

diff --git a/src/data/DebuggingJsonDeserializer.java b/src/data/DebuggingJsonDeserializer.java
new file mode 100644
index 0000000..1b00d4d
--- /dev/null
+++ b/src/data/DebuggingJsonDeserializer.java
@@ -0,0 +1,41 @@
+package data;
+
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParseException;
+import java.lang.reflect.Type;
+
+/**
+ * Validates the deserialization of a JSON string. The main motivation of this
+ * class is to print the property name of an object that throws an
+ * IllegalStateException because a string was expected, but a different type got
+ * returned.
+ *
+ * @author Peter Wu
+ */
+public class DebuggingJsonDeserializer extends ValidatingJsonDeserializer {
+
+    private final Class overriddenClass;
+
+    private DebuggingJsonDeserializer(Class overriddenClass) {
+        this.overriddenClass = overriddenClass;
+    }
+
+    @Override
+    public Object deserialize(JsonElement je, Type type,
+            JsonDeserializationContext jdc) throws JsonParseException {
+        checkObject("", je, overriddenClass);
+        return null;
+    }
+
+    public static void tryValidate(String json, Class cls) {
+        new GsonBuilder()
+                .registerTypeAdapter(Dummy.class, new DebuggingJsonDeserializer(cls))
+                .create()
+                .fromJson(json, Dummy.class);
+    }
+
+    private class Dummy {
+    }
+}
diff --git a/src/data/ValidatingJsonDeserializer.java b/src/data/ValidatingJsonDeserializer.java
index c168821..f44b681 100644
--- a/src/data/ValidatingJsonDeserializer.java
+++ b/src/data/ValidatingJsonDeserializer.java
@@ -30,7 +30,7 @@ public class ValidatingJsonDeserializer<T> implements JsonDeserializer<T> {
         return obj;
     }
 
-    private void checkObject(String path, JsonElement je, Class type) {
+    void checkObject(String path, JsonElement je, Class type) {
         JsonObject jsonObj = je.getAsJsonObject();
         for (Field f : type.getDeclaredFields()) {
             JsonElement val = jsonObj.get(f.getName());