Preserve comments when writing to config file.

pgcli/config.py

@@ -18,11 +18,15 @@ def config_location():
 
 
 def load_config(usr_cfg, def_cfg=None):
-    cfg = ConfigObj()
-    cfg.merge(ConfigObj(def_cfg, interpolation=False))
-    cfg.merge(ConfigObj(expanduser(usr_cfg), interpolation=False, encoding="utf-8"))
+    # avoid config merges when possible. For writing, we need an umerged config instance.
+    # see https://github.com/dbcli/pgcli/issues/1240 and https://github.com/DiffSK/configobj/issues/171
+    if def_cfg:
+        cfg = ConfigObj()
+        cfg.merge(ConfigObj(def_cfg, interpolation=False))
+        cfg.merge(ConfigObj(expanduser(usr_cfg), interpolation=False, encoding="utf-8"))
+    else:
+        cfg = ConfigObj(expanduser(usr_cfg), interpolation=False, encoding="utf-8")
     cfg.filename = expanduser(usr_cfg)
-
     return cfg
 
 
@@ -46,12 +50,16 @@ def upgrade_config(config, def_config):
     cfg.write()
 
 
+def get_config_filename(pgclirc_file=None):
+    return pgclirc_file or "%sconfig" % config_location()
+
+
 def get_config(pgclirc_file=None):
     from pgcli import __file__ as package_root
 
     package_root = os.path.dirname(package_root)
 
-    pgclirc_file = pgclirc_file or "%sconfig" % config_location()
+    pgclirc_file = get_config_filename(pgclirc_file)
 
     default_config = os.path.join(package_root, "pgclirc")
     write_default_config(default_config, pgclirc_file)

pgcli/main.py

@@ -63,6 +63,7 @@ from .config import (
     config_location,
     ensure_dir_exists,
     get_config,
+    get_config_filename
 )
 from .key_bindings import pgcli_bindings
 from .packages.prompt_utils import confirm_destructive_query
@@ -176,7 +177,11 @@ class PGCli:
         # Load config.
         c = self.config = get_config(pgclirc_file)
 
-        NamedQueries.instance = NamedQueries.from_config(self.config)
+        # at this point, config should be written to pgclirc_file if it did not exist. Read it.
+        self.config_writer = load_config(get_config_filename(pgclirc_file))
+
+        # make sure to use self.config_writer, not self.config
+        NamedQueries.instance = NamedQueries.from_config(self.config_writer)
 
         self.logger = logging.getLogger(__name__)
         self.initialize_logging()