json_db: do not overload load_data.

instead, pass an upgrader function to the constructor.

electrum/json_db.py

@@ -166,31 +166,59 @@ class StoredDict(dict):
 
 class JsonDB(Logger):
 
-    def __init__(self, s: str, storage=None, encoder=None):
+    def __init__(self, s: str, storage=None, encoder=None, upgrader=None):
         Logger.__init__(self)
         self.lock = threading.RLock()
         self.storage = storage
         self.encoder = encoder
         self._modified = False
         # load data
-        data, was_upgraded = self.load_data(s)
+        data = self.load_data(s)
+        if upgrader:
+            data, was_upgraded = upgrader(data)
+        else:
+            was_upgraded = False
         # convert to StoredDict
         self.data = StoredDict(data, self, [])
+        # note: self._modified may have been affected by StoredDict
+        self._modified = was_upgraded
         # write file in case there was a db upgrade
-        if was_upgraded and self.storage and self.storage.file_exists():
+        if self.storage and self.storage.file_exists():
             self.write()
 
     def load_data(self, s:str) -> dict:
         """ overloaded in wallet_db """
         if s == '':
-            return {}, False
+            return {}
         try:
             data = json.loads(s)
         except Exception:
+            if r := self.maybe_load_ast_data(s):
+                data = r
+            else:
                 raise WalletFileException("Cannot read wallet file. (parsing failed)")
         if not isinstance(data, dict):
             raise WalletFileException("Malformed wallet file (not dict)")
-        return data, False
+        return data
+
+    def maybe_load_ast_data(self, s):
+        """ for old wallets """
+        try:
+            import ast
+            d = ast.literal_eval(s)
+            labels = d.get('labels', {})
+        except Exception as e:
+            return
+        data = {}
+        for key, value in d.items():
+            try:
+                json.dumps(key)
+                json.dumps(value)
+            except Exception:
+                self.logger.info(f'Failed to convert label to json format: {key}')
+                continue
+            data[key] = value
+        return data
 
     def set_modified(self, b):
         with self.lock:

electrum/wallet_db.py

@@ -32,6 +32,7 @@ from collections import defaultdict
 from typing import Dict, Optional, List, Tuple, Set, Iterable, NamedTuple, Sequence, TYPE_CHECKING, Union
 import binascii
 import time
+from functools import partial
 
 import attr
 
@@ -1172,36 +1173,8 @@ class WalletDBUpgrader(Logger):
         raise WalletFileException(msg)
 
 
-class WalletDB(JsonDB):
+def upgrade_wallet_db(data: dict, do_upgrade) -> Tuple[dict, bool]:
-
+    was_upgraded = False
-    def __init__(self, s, *, storage=None, upgrade=False):
-        self._upgrade = upgrade
-        JsonDB.__init__(self, s, storage, encoder=MyEncoder)
-        # create pointers
-        self.load_transactions()
-        # load plugins that are conditional on wallet type
-        self.load_plugins()
-
-    def load_data(self, s):
-        try:
-            data, _ = JsonDB.load_data(self, s)
-        except Exception:
-            try:
-                d = ast.literal_eval(s)
-                labels = d.get('labels', {})
-            except Exception as e:
-                raise WalletFileException("Cannot read wallet file. (parsing failed)")
-            data = {}
-            for key, value in d.items():
-                try:
-                    json.dumps(key)
-                    json.dumps(value)
-                except Exception:
-                    self.logger.info(f'Failed to convert label to json format: {key}')
-                    continue
-                data[key] = value
-        if not isinstance(data, dict):
-            raise WalletFileException("Malformed wallet file (not dict)")
 
     if len(data) == 0:
         # create new DB
@@ -1213,12 +1186,12 @@ class WalletDB(JsonDB):
         )
         assert data.get("db_metadata", None) is None
         data["db_metadata"] = v
+        was_upgraded = True
 
     dbu = WalletDBUpgrader(data)
-        was_upgraded = False
     if dbu.requires_split():
         raise WalletRequiresSplit(dbu.get_split_accounts())
-        if dbu.requires_upgrade() and self._upgrade:
+    if dbu.requires_upgrade() and do_upgrade:
         dbu.upgrade()
         was_upgraded = True
     if dbu.requires_upgrade():
@@ -1226,6 +1199,15 @@ class WalletDB(JsonDB):
     return dbu.data, was_upgraded
 
 
+class WalletDB(JsonDB):
+
+    def __init__(self, s, *, storage=None, upgrade=False):
+        JsonDB.__init__(self, s, storage, encoder=MyEncoder, upgrader=partial(upgrade_wallet_db, do_upgrade=upgrade))
+        # create pointers
+        self.load_transactions()
+        # load plugins that are conditional on wallet type
+        self.load_plugins()
+
     @locked
     def get_seed_version(self):
         return self.get('seed_version')