Allow defining a json file with preferred aliases

At $WORK we have a lot of tables with names like `foo_noun_verb` or
`foo_noun_related-noun_verb` and so while the default aliasing is very
helpful for shortening unwieldy names we do end up with lots of aliases
like `LEFT JOIN fnv on fnv2.id = fnv.fnv2_id`

This change will allow defining a json file of preferred aliases

```
> cat ~/.config/pgcli/aliases.json
{
    "foo_user": "user",
    "foo_user_group": "user_group"
}
```

so the alias suggestion for `SELECT * FROM foo_user` will be `SELECT * FROM foo_user AS user`
instead of the default `SELECT * FROM foo_user AS fu`

changelog.rst

@@ -4,10 +4,13 @@ Upcoming
 Features:
 ---------
 
-* Changed the `destructive_warning` config to be a list of commands that are considered 
+* Changed the `destructive_warning` config to be a list of commands that are considered
   destructive. This would allow you to be warned on `create`, `grant`, or `insert` queries.
 * Destructive warnings will now include the alias dsn connection string name if provided (-D option).
 * pgcli.magic will now work with connection URLs that use TLS client certificates for authentication
+* Allow specifying an `alias_map_file` in the config that will use
+  predetermined table aliases instead of generating aliases programmatically on
+  the fly
 
 3.5.0 (2022/09/15):
 ===================

pgcli/main.py

@@ -269,6 +269,7 @@ def __init__(
             "single_connection": single_connection,
             "less_chatty": less_chatty,
             "keyword_casing": keyword_casing,
+            "alias_map_file": c["main"]["alias_map_file"] or None,
         }
 
         completer = PGCompleter(

pgcli/pgclirc

@@ -24,7 +24,7 @@ multi_line_mode = psql
 
 # Destructive warning will alert you before executing a sql statement
 # that may cause harm to the database such as "drop table", "drop database",
-# "shutdown", "delete", or "update". 
+# "shutdown", "delete", or "update".
 # You can pass a list of destructive commands or leave it empty if you want to skip all warnings.
 # "unconditional_update" will warn you of update statements that don't have a where clause
 destructive_warning = drop, shutdown, delete, truncate, alter, update, unconditional_update
@@ -38,6 +38,14 @@ auto_expand = False
 # If set to True, table suggestions will include a table alias
 generate_aliases = False
 
+# Path to a json file that specifies specific table aliases to use when generate_aliases is set to True
+# the format for this file should be:
+# {
+#     "some_table_name": "desired_alias",
+#     "some_other_table_name": "another_alias"
+# }
+alias_map_file = ""
+
 # log_file location.
 # In Unix/Linux: ~/.config/pgcli/log
 # In Windows: %USERPROFILE%\AppData\Local\dbcli\pgcli\log

pgcli/pgcompleter.py

@@ -61,12 +61,14 @@ def Candidate(
 normalize_ref = lambda ref: ref if ref[0] == '"' else '"' + ref.lower() + '"'
 
 
-def generate_alias(tbl):
+def generate_alias(tbl, alias_map=None):
     """Generate a table alias, consisting of all upper-case letters in
     the table name, or, if there are no upper-case letters, the first letter +
     all letters preceded by _
     param tbl - unescaped name of the table to alias
     """
+    if alias_map and tbl in alias_map:
+        return alias_map[tbl]
     return "".join(
         [l for l in tbl if l.isupper()]
         or [l for l, prev in zip(tbl, "_" + tbl) if prev == "_" and l != "_"]
@@ -100,6 +102,15 @@ def __init__(self, smart_completion=True, pgspecial=None, settings=None):
         self.call_arg_oneliner_max = settings.get("call_arg_oneliner_max", 2)
         self.search_path_filter = settings.get("search_path_filter")
         self.generate_aliases = settings.get("generate_aliases")
+
+        # when should this file be loaded? IO in constructors is not my preference but slow startup is
+        # probably better than slow first query
+        alias_map_file = settings.get("alias_map_file")
+        if alias_map_file is not None:
+            with open(alias_map_file) as fo:
+                self.alias_map = json.load(fo)
+        else:
+            self.alias_map = None
         self.casing_file = settings.get("casing_file")
         self.insert_col_skip_patterns = [
             re.compile(pattern)