Add db type alias information to db types endpoint

db/types/aliases.py

@@ -0,0 +1,34 @@
+from frozendict import frozendict
+
+
+# Copied (and reordered) from table in
+# https://www.postgresql.org/docs/11/datatype.html
+canonical_to_aliases = frozendict(
+    {
+        'boolean': ['bool'],
+        'bit varying': ['varbit'],
+        'smallint': ['int2'],
+        'integer': ['int', 'int4'],
+        'bigint': ['int8'],
+        'smallserial': ['serial2'],
+        'serial': ['serial4'],
+        'bigserial': ['serial8'],
+        'real': ['float4'],
+        'double precision': ['float8'],
+        'numeric': ['decimal'],
+        'character': ['char'],
+        'character varying': ['varchar'],
+        'time with timezone': ['timetz'],
+        'timestamp with timezone': ['timestamptz'],
+    }
+)
+
+alias_to_canonical = frozendict(
+    {
+        alias: canonical
+        for canonical, aliases
+        in canonical_to_aliases.items()
+        for alias
+        in aliases
+    }
+)

db/types/base.py

@@ -3,7 +3,7 @@
 from sqlalchemy import create_engine
 
 from db import constants
-
+from db.types.aliases import canonical_to_aliases, alias_to_canonical
 from db.functions import hints
 
 from frozendict import frozendict
@@ -14,7 +14,21 @@
 VARCHAR = 'varchar'
 
 
-class PostgresType(Enum):
+class DatabaseType:
+    @property
+    def is_canonical(self):
+        return self.value in canonical_to_aliases
+
+    @property
+    def aliases(self):
+        return canonical_to_aliases.get(self.value, [])
+
+    @property
+    def alias_of(self):
+        return alias_to_canonical.get(self.value)
+
+
+class PostgresType(DatabaseType, Enum):
     """
     This only includes built-in Postgres types that SQLAlchemy supports.
     SQLAlchemy doesn't support XML. See zzzeek's comment on:
@@ -66,7 +80,7 @@ class PostgresType(Enum):
     UUID = 'uuid'
 
 
-class MathesarCustomType(Enum):
+class MathesarCustomType(DatabaseType, Enum):
     """
     This is a list of custom Mathesar DB types.
     Keys returned by get_available_types are of the format 'mathesar_types.VALUE'

mathesar/api/serializers/db_types.py

@@ -8,9 +8,14 @@ class DBTypeSerializer(serializers.Serializer):
     hints = serializers.ListField(child=serializers.DictField())
 
     def to_representation(self, db_type):
+        # TODO solve db type casing holistically
+        # https://github.com/centerofci/mathesar/issues/1036
+        uppercase_id = db_type.value.upper()
+        uppercased_aliases = [db_type_id.upper() for db_type_id in db_type.aliases]
+        uppercased_alias_of = db_type.alias_of.upper() if db_type.alias_of else None
         return {
-            # TODO solve db type casing holistically
-            # https://github.com/centerofci/mathesar/issues/1036
-            "id": db_type.value.upper(),
+            "id": uppercase_id,
+            "aliases": uppercased_aliases,
+            "alias_of": uppercased_alias_of,
             "hints": db_types_hinted.get(db_type, None),
         }