Fix: fixed migration to handle postgres json properly

backend/open_webui/internal/migrations/019_add_rag_config_to_knowledge.py

@@ -22,29 +22,63 @@
     > migrator.drop_constraints(model, *constraints)
 
 """
+"""Add rag_config field to knowledge table if not present."""
 from contextlib import suppress
-import peewee as pw
 from peewee_migrate import Migrator
+import peewee as pw
 import json
-with suppress(ImportError):
-    import playhouse.postgres_ext as pw_pext
 
-class Knowledge(pw.Model):
-    class Meta:
-        table_name = 'knowledge'
+# Try importing JSONField from playhouse.postgres_ext
+with suppress(ImportError):
+    from playhouse.postgres_ext import JSONField as PostgresJSONField
+
+
+# Fallback JSONField for SQLite (stores JSON as text)
+class SQLiteJSONField(pw.TextField):
+    def db_value(self, value):
+        return json.dumps(value)
+
+    def python_value(self, value):
+        if value is not None:
+            return json.loads(value)
+        return None
+
+
+def get_compatible_json_field(database: pw.Database):
+    """Return a JSON-compatible field for the current database."""
+    if isinstance(database, pw.SqliteDatabase):
+        return SQLiteJSONField(null=False, default={"DEFAULT_RAG_SETTINGS": True})
+    else:
+        return PostgresJSONField(null=False, default={"DEFAULT_RAG_SETTINGS": True})
+
 
 def migrate(migrator: Migrator, database: pw.Database, *, fake=False):
-    """Add rag_config column to knowledge table."""
-    Knowledge._meta.database = database  # manually bind DB
+    """Add rag_config JSON field to knowledge table"""
+    if 'knowledge' not in database.get_tables():
+        print("Knowledge table hasn't been created yet, skipping migration.")
+        return
+
+    class Knowledge(pw.Model):
+        class Meta:
+            table_name = 'knowledge'
+
+    Knowledge._meta.database = database  # bind DB
 
     migrator.add_fields(
         Knowledge,
-        rag_config=pw.TextField(null=True, default=json.dumps({"DEFAULT_RAG_SETTINGS": True})),
+        rag_config=get_compatible_json_field(database)
     )
 
 
 def rollback(migrator: Migrator, database: pw.Database, *, fake=False):
-    """Remove rag_config column from knowledge table."""
-    Knowledge._meta.database = database  # manually bind DB
+    """Remove rag_config field from knowledge table."""
+    if 'knowledge' not in database.get_tables():
+        print("Knowledge table hasn't been created yet, skipping migration.")
+        return
 
-    migrator.remove_fields(Knowledge, "rag_config")
+    class Knowledge(pw.Model):
+        class Meta:
+            table_name = 'knowledge'
+
+    Knowledge._meta.database = database
+    migrator.remove_fields(Knowledge, 'rag_config')