bug: migration from 3.x to 4.x with MVStore module fails

[DarkAtra]

The wiki states that

Nitrite will try to migrate your existing database to the latest version on the best effort basis without any guarantee provided you are using the MVStore module.

However, it seems like it fails to migrate document ids correctly. Version 3.x uses a Long to represent the internal document _id. In version 4.x this code changed to use a String instead. When using version 4.x to read a database that was created with version 3.x the following exception occurs when updating a document:

org.dizitart.no2.exceptions.InvalidIdException: Invalid _id found 21601262100400

Test case (includes a v3 database): https://github.com/DarkAtra/nitrite-java/blob/bug/id-migration-for-old-documents-fails/nitrite-mvstore-adapter/src/test/java/org/dizitart/no2/NitriteTest.java#L449-L479

Steps to reproduce:

• create a database with nitrite version 3.x
• create a collection with a single document
• update nitrite to version 4.x
• get the document from the collection and update any field
• invoke update to persist the changes
• you should now see the above exception

Is this expected? If so, what would be the best way for me to update existing documents so that they function correctly with version 4.x of nitrite?

[DarkAtra]

This might do the trick:

Subject: [PATCH] bug: migration from 3.x to 4.x with MVStore module fails
---
Index: nitrite-mvstore-adapter/src/main/java/org/dizitart/no2/mvstore/compat/v1/UpgradeUtil.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/nitrite-mvstore-adapter/src/main/java/org/dizitart/no2/mvstore/compat/v1/UpgradeUtil.java b/nitrite-mvstore-adapter/src/main/java/org/dizitart/no2/mvstore/compat/v1/UpgradeUtil.java
--- a/nitrite-mvstore-adapter/src/main/java/org/dizitart/no2/mvstore/compat/v1/UpgradeUtil.java	(revision 03fd0f7cc41c6ba1f6cbf13a56ccbf08700a2b7d)
+++ b/nitrite-mvstore-adapter/src/main/java/org/dizitart/no2/mvstore/compat/v1/UpgradeUtil.java	(revision 9f1f34ecb9e3d48a68fb53c6be7da3f7eaaf20e9)
@@ -190,7 +190,13 @@
         Document document = Document.createDocument();
         for (Map.Entry<String, Object> entry : value.entrySet()) {
             Object val = entry.getValue();
-            Object migratedVal = migrateValue(val);
+
+            Object migratedVal;
+            if (DOC_ID.equals(entry.getKey())) {
+                migratedVal = Long.toString((long) val);
+            } else {
+                migratedVal = migrateValue(val);
+            }
             document.put(entry.getKey(), migratedVal);
         }
         return document;

[anidotnet]

Thanks for reporting this issue and providing the solution as well. This fix will be in 4.3.0-SNAPSHOT in a while.