fix: Raise DataError dumping lists of mixed types

This requires more checking dumping lists, but the alternative is to
guard every single dumper, which is painful as well, and more brittle.

diff --git a/docs/news.rst b/docs/news.rst
index b8ca1e21a3e134667b77185c71c1052add6f2335..4f8f8cc2195839a829c573d80241c41e312fc36c 100644 (file)
--- a/docs/news.rst
+++ b/docs/news.rst
@@ -31,7 +31,7 @@ Psycopg 3.1 (unreleased)
 Psycopg 3.0.14 (unreleased)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-- Fail dumping arrays of mixed numbers with DataError (:ticket:`#301`).
+- Raise `DataError` dumping arrays of mixed types (:ticket:`#301`).
 
 
 Current release

diff --git a/psycopg/psycopg/types/array.py b/psycopg/psycopg/types/array.py
index f2b28cdec068aa5b2086c1a51395140a29035093..fe1e311bd0dc64bf129712e2b9a413456c64707f 100644 (file)
--- a/psycopg/psycopg/types/array.py
+++ b/psycopg/psycopg/types/array.py
@@ -47,23 +47,30 @@ class BaseListDumper(RecursiveDumper):
         """
         Find the first non-null element of an eventually nested list
         """
-        it = self._flatiter(L, set())
-        try:
-            item = next(it)
-        except StopIteration:
+        items = list(self._flatiter(L, set()))
+        types = set(map(type, items))
+        if not types:
             return None
+        if len(types) > 1:
+            raise e.DataError(
+                "cannot dump lists of mixed types;"
+                f" got: {', '.join(sorted(t.__name__ for t in types))}"
+            )
+        t = types.pop()
 
         # Checking for precise type. If the type is a subclass (e.g. Int4)
         # we assume the user knows what type they are passing.
-        if type(item) is not int:
-            return item
+        if t is not int:
+            return items[0]
 
         # If we got an int, let's see what is the biggest one in order to
         # choose the smallest OID and allow Postgres to do the right cast.
-        it = self._flatiter(L, set())
-        imax = max((i if i >= 0 else -i - 1 for i in it), default=0)
-        imax = max(item if item >= 0 else -item - 1, imax)
-        return imax
+        imax: int = max(items)
+        imin: int = min(items)
+        if imin >= 0:
+            return imax
+        else:
+            return max(imax, -imin - 1)
 
     def _flatiter(self, L: List[Any], seen: Set[int]) -> Any:
         if id(L) in seen:
@@ -118,7 +125,7 @@ class ListDumper(BaseListDumper):
             # Empty lists can only be dumped as text if the type is unknown.
             return self
 
-        sd = self._tx.get_dumper(item, format.from_pq(self.format))
+        sd = self._tx.get_dumper(item, PyFormat.from_pq(self.format))
         dumper = type(self)(self.cls, self._tx)
         dumper.sub_dumper = sd
 

diff --git a/tests/types/test_array.py b/tests/types/test_array.py
index 5abf207e90132a08931688ae44736163bb68f2f6..6ea1971012ffc6de54906c56cfe415b5a19a0270 100644 (file)
--- a/tests/types/test_array.py
+++ b/tests/types/test_array.py
@@ -1,4 +1,3 @@
-from enum import Enum
 from decimal import Decimal
 
 import pytest
@@ -185,17 +184,6 @@ def test_list_number_wrapper(conn, wrapper, fmt_in, fmt_out):
 
 
 def test_mix_types(conn):
-    class MyEnum(int, Enum):
-        ONE = 2**30
-
-    cur = conn.execute("select %s", ([1, MyEnum.ONE],))
-    assert cur.fetchone() == ([1, 2**30],)
-    assert cur.description[0].type_code == cur.adapters.types["int4"].array_oid
-
-    cur = conn.execute("select %s", ([1, psycopg.types.numeric.Int8(2**60)],))
-    assert cur.fetchone() == ([1, 2**60],)
-    assert cur.description[0].type_code == cur.adapters.types["int8"].array_oid
-
     with pytest.raises(psycopg.DataError):
         conn.execute("select %s", ([1, 0.5],))