Implement pg.needs_password() specifically for Psycopg 3.1+

Psycopg 3 links exceptions to the underlying libpq PGconn object, which
exposes a 'needs_password' property; exactly what we need and much more
robust than parsing the error message.

CHANGELOG.md

@@ -15,6 +15,8 @@
 
 * Document how to *hack* on pg\_activity in the `README`.
 * Add a [pre-commit](https://pre-commit.com/) configuration.
+* Require psycopg >= 3.1 (when using the psycopg backend) to get a more robust
+  detection of connection password need.
 
 ## pg\_activity 3.4.2 - 2023-06-01
 

pgactivity/pg.py

@@ -180,6 +180,10 @@ def decode(value: bytes, pgenc: bytes, *, errors: str) -> str:
             pyenc = "utf-8"
         return value.decode(pyenc, errors=errors)
 
+    def needs_password(exc: OperationalError) -> bool:
+        assert exc.pgconn is not None
+        return exc.pgconn.needs_password
+
 except ImportError:
     import codecs
 
@@ -270,15 +274,14 @@ def decode(value: bytes, pgenc: bytes, *, errors: str) -> str:
             pyenc = "utf-8"
         return value.decode(pyenc, errors=errors)
 
-
-def needs_password(exc: OperationalError) -> bool:
-    if isinstance(exc, InvalidPassword):
-        return True
-    msg = str(exc)
-    return (
-        msg.startswith("FATAL:  password authentication failed for user")
-        or "fe_sendauth: no password supplied" in msg
-    )
+    def needs_password(exc: OperationalError) -> bool:
+        if isinstance(exc, InvalidPassword):
+            return True
+        msg = str(exc)
+        return (
+            msg.startswith("FATAL:  password authentication failed for user")
+            or "fe_sendauth: no password supplied" in msg
+        )
 
 
 __all__ = [

pyproject.toml

@@ -60,7 +60,7 @@ typing = [
     "types-setuptools",
 ]
 psycopg = [
-    "psycopg[binary]",
+    "psycopg[binary] >= 3.1",
 ]
 psycopg2 = [
     "psycopg2-binary >= 2.8",