[Confluence] Server attach_content: always POST to update an attachment

atlassian/confluence/server/__init__.py

@@ -1437,26 +1437,16 @@ def attach_content(
                         raise
 
                 if existing_attachment:
-                    # Update existing attachment on the specific attachment ID
+                    # Update existing attachment on the specific attachment ID. Server/Data Center
+                    # only accepts POST on the data path below the child, whatever api_version is set.
                     attachment_id = existing_attachment["id"]
-                    if self.api_version == "1.0":
-                        # older API versions use POST on data path below the child
-                        update_path = f"{path}/{attachment_id}/data"
-                        response = self.post(
-                            path=update_path,
-                            data=data,
-                            headers=headers,
-                            files={"file": (name, content, content_type)},
-                        )
-                    else:
-                        # newer API versions use PUT on a path derived from the attachment ID directly
-                        update_path = f"rest/api/content/{attachment_id}"
-                        response = self.put(
-                            path=update_path,
-                            data=data,
-                            headers=headers,
-                            files={"file": (name, content, content_type)},
-                        )
+                    update_path = f"{path}/{attachment_id}/data"
+                    response = self.post(
+                        path=update_path,
+                        data=data,
+                        headers=headers,
+                        files={"file": (name, content, content_type)},
+                    )
                 else:
                     # Create new attachment using POST
                     response = self.post(

tests/confluence/test_confluence_server.py

@@ -190,6 +190,23 @@ def test_attach_content_normalizes_path_like_attachment_names(self, mock_post, m
 
         assert mock_post.call_args.kwargs["files"] == {"file": ("diagram.png", content, "image/png")}
 
+    @pytest.mark.parametrize("api_version", [None, "latest", "1.0"], ids=["default", "latest", "1.0"])
+    @patch.object(ConfluenceServer, "put")
+    @patch.object(ConfluenceServer, "get")
+    @patch.object(ConfluenceServer, "post")
+    def test_attach_content_updates_existing_attachment_with_post(self, mock_post, mock_get, mock_put, api_version):
+        kwargs = {} if api_version is None else {"api_version": api_version}
+        confluence = ConfluenceServer(url="https://test.confluence.com", username="test", password="test", **kwargs)
+        content = io.BytesIO(b"new image")
+        mock_get.return_value = {"results": [{"id": "att-1", "title": "diagram.png"}]}
+        mock_post.return_value = {"id": "att-1"}
+
+        confluence.attach_content(content, "diagram.png", "image/png", page_id="123")
+
+        mock_put.assert_not_called()
+        assert mock_post.call_args.kwargs["path"] == "rest/api/content/123/child/attachment/att-1/data"
+        assert mock_post.call_args.kwargs["files"] == {"file": ("diagram.png", content, "image/png")}
+
     def test_attach_content_rejects_empty_attachment_name(self, confluence_server):
         with pytest.raises(ApiValueError, match="must contain a filename"):
             confluence_server.attach_content(io.BytesIO(b"content"), "/", page_id="123")