feat: add Transformer.from_context() method

Allow to reuse the same transformer in nested context, instead of
creating new ones. Even if transformer copies are shallow, we may end up
creating several in certain places.

diff --git a/psycopg/psycopg/_transform.py b/psycopg/psycopg/_transform.py
index 11194558be4de71c894dacd78c8a2f4902e66735..4f93f3639e3c6bb70cce1f8d69d51caf68a1ca4d 100644 (file)
--- a/psycopg/psycopg/_transform.py
+++ b/psycopg/psycopg/_transform.py
@@ -75,6 +75,18 @@ class Transformer(AdaptContext):
         # the length of the result columns
         self._row_loaders: List[LoadFunc] = []
 
+    @classmethod
+    def from_context(cls, context: Optional[AdaptContext]) -> "Transformer":
+        """
+        Return a Transformer from an AdaptContext.
+
+        If the context is a Transformer instance, just return it.
+        """
+        if isinstance(context, Transformer):
+            return context
+        else:
+            return cls(context)
+
     @property
     def connection(self) -> Optional["BaseConnection[Any]"]:
         return self._conn

diff --git a/psycopg/psycopg/abc.py b/psycopg/psycopg/abc.py
index d23873fe56e25edfe5102f5d0d93af20c4b5ddee..0bbcebe29d51e5bfc4b62d66c01182465163b8b1 100644 (file)
--- a/psycopg/psycopg/abc.py
+++ b/psycopg/psycopg/abc.py
@@ -196,6 +196,10 @@ class Transformer(Protocol):
     def __init__(self, context: Optional[AdaptContext] = None):
         ...
 
+    @classmethod
+    def from_context(cls, context: Optional[AdaptContext]) -> "Transformer":
+        ...
+
     @property
     def connection(self) -> Optional["BaseConnection[Any]"]:
         ...

diff --git a/psycopg/psycopg/adapt.py b/psycopg/psycopg/adapt.py
index 8341a5a29981c14a9a6327ecba453c245dad440d..ccf89ce2fbb6a6b9800c58ace717073b7f00c9db 100644 (file)
--- a/psycopg/psycopg/adapt.py
+++ b/psycopg/psycopg/adapt.py
@@ -151,7 +151,7 @@ class RecursiveDumper(Dumper):
 
     def __init__(self, cls: type, context: Optional[abc.AdaptContext] = None):
         super().__init__(cls, context)
-        self._tx = Transformer(context)
+        self._tx = Transformer.from_context(context)
 
 
 class RecursiveLoader(Loader):
@@ -159,4 +159,4 @@ class RecursiveLoader(Loader):
 
     def __init__(self, oid: int, context: Optional[abc.AdaptContext] = None):
         super().__init__(oid, context)
-        self._tx = Transformer(context)
+        self._tx = Transformer.from_context(context)

diff --git a/psycopg/psycopg/sql.py b/psycopg/psycopg/sql.py
index ade3e4de4bbb4b5101c79d578affa898848edd59..39ecfc9e821fd92aff2127bf640c899d55ecb36b 100644 (file)
--- a/psycopg/psycopg/sql.py
+++ b/psycopg/psycopg/sql.py
@@ -390,7 +390,7 @@ class Literal(Composable):
     """
 
     def as_bytes(self, context: Optional[AdaptContext]) -> bytes:
-        tx = Transformer(context)
+        tx = Transformer.from_context(context)
         dumper = tx.get_dumper(self._obj, PyFormat.TEXT)
         return dumper.quote(self._obj)
 

diff --git a/psycopg/psycopg/types/composite.py b/psycopg/psycopg/types/composite.py
index a5340993e048091b7621678014a4459ee9232e2a..4174854b1e8d6a83651f126eefbaed011efddb40 100644 (file)
--- a/psycopg/psycopg/types/composite.py
+++ b/psycopg/psycopg/types/composite.py
@@ -13,7 +13,7 @@ from typing import Sequence, Tuple, Type
 from .. import pq
 from .. import postgres
 from ..abc import AdaptContext, Buffer
-from ..adapt import PyFormat, RecursiveDumper, RecursiveLoader
+from ..adapt import Transformer, PyFormat, RecursiveDumper, Loader
 from .._struct import pack_len, unpack_len
 from ..postgres import TEXT_OID
 from .._typeinfo import CompositeInfo as CompositeInfo  # exported here
@@ -94,7 +94,11 @@ class TupleBinaryDumper(RecursiveDumper):
         return out
 
 
-class BaseCompositeLoader(RecursiveLoader):
+class BaseCompositeLoader(Loader):
+    def __init__(self, oid: int, context: Optional[AdaptContext] = None):
+        super().__init__(oid, context)
+        self._tx = Transformer(context)
+
     def _parse_record(self, data: bytes) -> Iterator[Optional[bytes]]:
         """
         Split a non-empty representation of a composite type into components.
@@ -138,11 +142,14 @@ class RecordLoader(BaseCompositeLoader):
         )
 
 
-class RecordBinaryLoader(RecursiveLoader):
-
+class RecordBinaryLoader(Loader):
     format = pq.Format.BINARY
     _types_set = False
 
+    def __init__(self, oid: int, context: Optional[AdaptContext] = None):
+        super().__init__(oid, context)
+        self._tx = Transformer(context)
+
     def load(self, data: Buffer) -> Tuple[Any, ...]:
         if not self._types_set:
             self._config_types(data)

diff --git a/psycopg_c/psycopg_c/_psycopg.pyi b/psycopg_c/psycopg_c/_psycopg.pyi
index 6668e337f4b8396e9217cc873e4e7688b7a6ce0f..3bcd4961d76b5d5346d3565edb8f23c82d5f805c 100644 (file)
--- a/psycopg_c/psycopg_c/_psycopg.pyi
+++ b/psycopg_c/psycopg_c/_psycopg.pyi
@@ -22,6 +22,8 @@ class Transformer(abc.AdaptContext):
     types: Optional[Tuple[int, ...]]
     formats: Optional[List[pq.Format]]
     def __init__(self, context: Optional[abc.AdaptContext] = None): ...
+    @classmethod
+    def from_context(cls, context: Optional[abc.AdaptContext]) -> "Transformer": ...
     @property
     def connection(self) -> Optional[BaseConnection[Any]]: ...
     @property

diff --git a/psycopg_c/psycopg_c/_psycopg/transform.pyx b/psycopg_c/psycopg_c/_psycopg/transform.pyx
index ffd8bf99ed2e664b9af18c8b2ad3fe8ce9c3e26d..9544de84f0fae65c05f8133e4efe4e35024fc30a 100644 (file)
--- a/psycopg_c/psycopg_c/_psycopg/transform.pyx
+++ b/psycopg_c/psycopg_c/_psycopg/transform.pyx
@@ -104,6 +104,18 @@ cdef class Transformer:
 
         self.types = self.formats = None
 
+    @classmethod
+    def from_context(cls, context: Optional["AdaptContext"]):
+        """
+        Return a Transformer from an AdaptContext.
+
+        If the context is a Transformer instance, just return it.
+        """
+        if isinstance(context, Transformer):
+            return context
+        else:
+            return cls(context)
+
     @property
     def pgresult(self) -> Optional[PGresult]:
         return self._pgresult