Raise an error when downloading non-existent files

from a data object

Author: marcellevstek

docs/CHANGELOG.rst

@@ -4,6 +4,16 @@ Change Log
 
 All notable changes to this project are documented in this file.
 
+==========
+Unreleased
+==========
+
+Fixed
+-----
+- Raise an error if a user calls the download method
+  on a data object and inputs a non-existing file or field name
+
+
 ===================
 22.2.3 - 2026-02-18
 ===================

src/resdk/resources/data.py

@@ -284,6 +284,12 @@ def download(
         file_names = self.files(file_name, field_name)
         files = ["{}/{}".format(self.id, fname) for fname in file_names]
 
+        if not files:
+            raise ValueError(
+                f"Data object contains no files with "
+                f"{'file name: ' + repr(file_name) if file_name else 'field name: ' + repr(field_name)}."
+            )
+
         self.resolwe._download_files(
             files=files, download_dir=download_dir, show_progress=show_progress
         )

tests/functional/docs/e2e_docs.py

@@ -165,6 +165,8 @@ def test_start(self):
             replace_lines=[
                 (4, "res = resdk.Resolwe(url='{}')\n".format(URL)),
                 (5, "res.login('{}', '{}')\n".format(USER_EMAIL, USER_PASSWORD)),
+                # Skip download, since data objects have not finished processing
+                (49, "\n"),
             ],
         )
 
@@ -233,6 +235,10 @@ def test_tutorial_create(self):
                 # is replaced with an empty line. There is now way to perform
                 # download if data objects are still processing and/or have not
                 # produced any stdout.txt. So just write an empty line:
+                (9, "\n"),
+                (10, "\n"),
+                (11, "\n"),
+                (12, "\n"),
                 (107, "\n"),
             ],
         )