Preserve lower-/upper-case mode of UUIDs and render them back accordingly

Author: Sergey Vasilyev

data_diff/abcs/database_types.py

@@ -217,7 +217,14 @@ class Native_UUID(ColType_UUID):
 
 @attrs.define(frozen=True)
 class String_UUID(ColType_UUID, StringType):
-    pass
+    # Case is important for UUIDs stored as regular string, not native UUIDs stored as numbers.
+    # We slice them internally as numbers, but render them back to SQL as lower/upper case.
+    # None means we do not know for sure, behave as with False, but it might be unreliable.
+    lowercase: Optional[bool] = None
+    uppercase: Optional[bool] = None
+
+    def make_value(self, v: str) -> ArithUUID:
+        return self.python_type(v, lowercase=self.lowercase, uppercase=self.uppercase)
 
 
 @attrs.define(frozen=True)

data_diff/databases/base.py

@@ -250,7 +250,7 @@ def _compile(self, compiler: Compiler, elem) -> str:
             return f"b'{elem.decode()}'"
         elif isinstance(elem, ArithUUID):
             s = f"'{elem.uuid}'"
-            return s
+            return s.upper() if elem.uppercase else s.lower() if elem.lowercase else s
         elif isinstance(elem, ArithString):
             return f"'{elem}'"
         assert False, elem
@@ -1115,7 +1115,10 @@ def _refine_coltypes(
                     )
                 else:
                     assert col_name in col_dict
-                    col_dict[col_name] = String_UUID()
+                    col_dict[col_name] = String_UUID(
+                        lowercase=all(s == s.lower() for s in uuid_samples),
+                        uppercase=all(s == s.upper() for s in uuid_samples),
+                    )
                     continue
 
             if self.SUPPORTS_ALPHANUMS:  # Anything but MySQL (so far)

data_diff/utils.py

@@ -151,6 +151,9 @@ class ArithUUID(ArithString):
     "A UUID that supports basic arithmetic (add, sub)"
 
     uuid: UUID = attrs.field(converter=_any_to_uuid)
+    lowercase: Optional[bool] = None
+    uppercase: Optional[bool] = None
+
     def range(self, other: "ArithUUID", count: int) -> List[Self]:
         assert isinstance(other, ArithUUID)
         checkpoints = split_space(self.uuid.int, other.uuid.int, count)