From f3881c33803aefeb48f31cb88692f14b8603714d Mon Sep 17 00:00:00 2001
From: Julien Bouquiaux <julien.bouquiaux@uclouvain.be>
Date: Mon, 5 Oct 2026 15:25:40 +0200
Subject: [PATCH] Copy all fields when creating an item from any existing item
 type

`_copy_sample_from_id` only replaced the request with the copied document
inside its `samples` / `cells` branches, so copying any other type (custom
item types, starting materials, ) created an empty item.

The copied document is now always used, constituent lists are merged based on
the fields present rather than the item type, and copying between different
types is rejected
---
 pydatalab/src/pydatalab/routes/v0_1/items.py | 66 ++++++++++----------
 1 file changed, 32 insertions(+), 34 deletions(-)

diff --git a/pydatalab/src/pydatalab/routes/v0_1/items.py b/pydatalab/src/pydatalab/routes/v0_1/items.py
index 7821a281b..aca5d7315 100644
--- a/pydatalab/src/pydatalab/routes/v0_1/items.py
+++ b/pydatalab/src/pydatalab/routes/v0_1/items.py
@@ -620,6 +620,16 @@ def search_items():
     return jsonify({"status": "success", "items": list(cursor)}), 200
 
 
+COPYABLE_CONSTITUENT_FIELDS: tuple[str, ...] = (
+    "synthesis_constituents",
+    "positive_electrode",
+    "negative_electrode",
+    "electrolyte",
+)
+"""Constituent list fields that are merged (rather than overwritten) when an item is
+created as a copy of another item."""
+
+
 def _copy_sample_from_id(sample_dict: dict, copy_from_item_id: str) -> dict:
     copied_doc = flask_mongo.db.items.find_one(
         {"item_id": copy_from_item_id, **get_default_permissions(user_only=False)}
@@ -647,47 +657,35 @@ def _copy_sample_from_id(sample_dict: dict, copy_from_item_id: str) -> dict:
     copied_doc.pop("blocks", None)
     copied_doc.pop("file_ObjectIds", None)
 
-    # any provided constituents will be added to the synthesis information table in
-    # addition to the constituents copied from the copy_from_item_id, avoiding duplicates
-    if copied_doc["type"] == "samples":
+    requested_type = sample_dict.get("type")
+    if requested_type and requested_type != copied_doc["type"]:
+        raise BadRequest(
+            f"Request to copy item with id {copy_from_item_id} of type {copied_doc['type']!r} "
+            f"into a new item of different type {requested_type!r} is not supported."
+        )
+
+    # any provided constituents will be added to the relevant constituent tables in
+    # addition to the constituents copied from the copy_from_item_id, avoiding duplicates.
+    # This is keyed on the fields present rather than the item type, so that custom item
+    # types inheriting these fields (e.g., `Sample` subclasses) are handled too.
+    for component in COPYABLE_CONSTITUENT_FIELDS:
+        if not isinstance(copied_doc.get(component), list):
+            continue
         existing_consituent_ids = [
-            constituent["item"].get("item_id", None)
-            for constituent in copied_doc["synthesis_constituents"]
+            constituent["item"].get("item_id", None) for constituent in copied_doc[component]
         ]
-        copied_doc["synthesis_constituents"] += [
+        copied_doc[component] += [
             constituent
-            for constituent in sample_dict.get("synthesis_constituents", [])
-            if constituent["item"].get("item_id") is None
+            for constituent in sample_dict.get(component, [])
+            if constituent["item"].get("item_id", None) is None
             or constituent["item"].get("item_id") not in existing_consituent_ids
         ]
 
-        original_collections = sample_dict.get("collections", [])
-        sample_dict = copied_doc
-
-        if original_collections:
-            sample_dict["collections"] = original_collections
-
-    elif copied_doc["type"] == "cells":
-        for component in (
-            "positive_electrode",
-            "negative_electrode",
-            "electrolyte",
-        ):
-            existing_consituent_ids = [
-                constituent["item"].get("item_id", None) for constituent in copied_doc[component]
-            ]
-            copied_doc[component] += [
-                constituent
-                for constituent in sample_dict.get(component, [])
-                if constituent["item"].get("item_id", None) is None
-                or constituent["item"].get("item_id") not in existing_consituent_ids
-            ]
-
-        original_collections = sample_dict.get("collections", [])
-        sample_dict = copied_doc
+    original_collections = sample_dict.get("collections", [])
+    sample_dict = copied_doc
 
-        if original_collections:
-            sample_dict["collections"] = original_collections
+    if original_collections:
+        sample_dict["collections"] = original_collections
 
     return sample_dict