From 9be617801a8dabe4bcae017c2f671c5c10b3aebb Mon Sep 17 00:00:00 2001
From: Peter Wu <peter@lekensteyn.nl>
Date: Fri, 9 May 2014 15:14:23 +0200
Subject: Trace object path for JSON validation errors.

---
 src/data/ValidatingJsonDeserializer.java | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

(limited to 'src/data/ValidatingJsonDeserializer.java')

diff --git a/src/data/ValidatingJsonDeserializer.java b/src/data/ValidatingJsonDeserializer.java
index e38f68f..511264d 100644
--- a/src/data/ValidatingJsonDeserializer.java
+++ b/src/data/ValidatingJsonDeserializer.java
@@ -26,14 +26,11 @@ public class ValidatingJsonDeserializer<T> implements JsonDeserializer<T> {
     public T deserialize(JsonElement je, Type type,
             JsonDeserializationContext jdc) throws JsonParseException {
         T obj = new Gson().fromJson(je, type);
-        checkObject(je, obj.getClass());
+        checkObject("", je, obj.getClass());
         return obj;
     }
 
-    private void checkObject(JsonElement je, Class type) {
-        if (!je.isJsonObject()) {
-            throw new JsonParseException("Expected object: " + type.getName());
-        }
+    private void checkObject(String path, JsonElement je, Class type) {
         JsonObject jsonObj = je.getAsJsonObject();
         for (Field f : type.getDeclaredFields()) {
             if (!jsonObj.has(f.getName())) {
@@ -41,14 +38,14 @@ public class ValidatingJsonDeserializer<T> implements JsonDeserializer<T> {
                     // null allowed, skip
                     continue;
                 }
-                throw new JsonParseException("Missing field: " + f.getName());
+                throw new JsonParseException("Missing field: " + path + f.getName());
             }
-            tryValidateProperty(jsonObj.get(f.getName()), f);
+            tryValidateProperty(path, jsonObj.get(f.getName()), f);
             // TODO: validate type?
         }
     }
 
-    private void tryValidateProperty(JsonElement je, Field f) {
+    private void tryValidateProperty(String path, JsonElement je, Field f) {
         // assume that this annotation is only applied to objects
         Validator v = f.getAnnotation(Validator.class);
         if (v != null) {
@@ -56,17 +53,19 @@ public class ValidatingJsonDeserializer<T> implements JsonDeserializer<T> {
             if (type.isArray()) {
                 // the class expects an array, so the value must have one too.
                 if (!je.isJsonArray()) {
-                    throw new JsonParseException("Not an array: " + f.getName());
+                    throw new JsonParseException("Not an array: " + path + f.getName());
                 }
                 JsonArray ja = je.getAsJsonArray();
                 type = type.getComponentType();
                 // for each array element, check if the object is valid.
+                path += f.getName() + "."; // e.g. foo[]
                 for (JsonElement arr_je : ja) {
-                    checkObject(arr_je, type);
+                    checkObject(path, arr_je, type);
                 }
             } else {
                 // not an array, assume a verifiable object
-                checkObject(je, type);
+                path += f.getName() + "."; // e.g. foo
+                checkObject(path, je, type);
             }
         }
     }
-- 
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