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Raise exception for uninstalled LoadImage reader and print writer pkg… #8915

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Raise exception for uninstalled LoadImage reader and print writer pkg…
VedhSontha Jun 11, 2026
5673b52
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Jun 12, 2026
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20 changes: 18 additions & 2 deletions monai/data/image_writer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -107,16 +107,32 @@ def resolve_writer(ext_name, error_if_not_found=True) -> Sequence:
fmt = fmt[1:]
avail_writers = []
default_writers = SUPPORTED_WRITERS.get(EXT_WILDCARD, ())
import re
errors = []
for _writer in look_up_option(fmt, SUPPORTED_WRITERS, default=default_writers):
try:
_writer() # this triggers `monai.utils.module.require_pkg` to check the system availability
avail_writers.append(_writer)
except OptionalImportError:
except OptionalImportError as e:
errors.append(str(e))
continue
except Exception: # other writer init errors indicating it exists
avail_writers.append(_writer)
if not avail_writers and error_if_not_found:
raise OptionalImportError(f"No ImageWriter backend found for {fmt}.")
required_pkgs = []
for err in errors:
match = re.search(r"required package `([^`]+)`", err)
if match:
pkg = match.group(1)
pkg = "pillow" if pkg == "PIL" else pkg
pkg = "pynrrd" if pkg == "nrrd" else pkg
if pkg not in required_pkgs:
required_pkgs.append(pkg)

msg = f"No ImageWriter backend found for {fmt}."
if required_pkgs:
msg += f" Please install: {' or '.join(required_pkgs)}."
raise OptionalImportError(msg)
writer_tuple = ensure_tuple(avail_writers)
SUPPORTED_WRITERS[fmt] = writer_tuple
return writer_tuple
Expand Down
13 changes: 9 additions & 4 deletions monai/transforms/io/array.py
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Original file line number Diff line number Diff line change
Expand Up @@ -209,13 +209,18 @@ def __init__(
the_reader = look_up_option(_r.lower(), SUPPORTED_READERS)
try:
self.register(the_reader(*args, **kwargs))
except OptionalImportError:
warnings.warn(
except OptionalImportError as e:
raise OptionalImportError(
f"required package for reader {_r} is not installed, or the version doesn't match requirement."
)
) from e
except TypeError: # the reader doesn't have the corresponding args/kwargs
warnings.warn(f"{_r} is not supported with the given parameters {args} {kwargs}.")

@coderabbitai coderabbitai Bot Jun 12, 2026

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⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Locate the file and show the relevant section around line 217
ls -la monai/transforms/io/array.py
python3 - <<'PY'
import itertools, pathlib
p = pathlib.Path("monai/transforms/io/array.py")
lines = p.read_text().splitlines()
start, end = 200, 240
for i in range(start-1, min(end, len(lines))):
    print(f"{i+1:4d}: {lines[i]}")
PY

# Find all warnings.warn occurrences in this file
rg -n "warnings\.warn\s*\(" monai/transforms/io/array.py

Repository: Project-MONAI/MONAI

Length of output: 2624

🏁 Script executed:

#!/bin/bash
set -euo pipefail
python3 - <<'PY'
import pathlib
p = pathlib.Path("monai/transforms/io/array.py")
lines = p.read_text().splitlines()
# show more context to identify surrounding def/class
for i in range(150, 230):
    if i < 0 or i >= len(lines): 
        continue
    print(f"{i+1:4d}: {lines[i]}")
PY

Repository: Project-MONAI/MONAI

Length of output: 5311

Add stacklevel=2 to the warning in LoadImage.__init__.

monai/transforms/io/array.py line 217 uses warnings.warn(...) without stacklevel, so the warning location points at MONAI internals instead of the user call site.

Suggested change 
-                    warnings.warn(f"{_r} is not supported with the given parameters {args} {kwargs}.")
+                    warnings.warn(
+                        f"{_r} is not supported with the given parameters {args} {kwargs}.",
+                        stacklevel=2,
+                    )
🧰 Tools
🪛 Ruff (0.15.15)

[warning] 217-217: No explicit stacklevel keyword argument found

Set stacklevel=2

(B028)

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@monai/transforms/io/array.py` at line 217, The warning call in
LoadImage.__init__ currently uses warnings.warn(f"{_r} is not supported with the
given parameters {args} {kwargs}.") which points the stack to MONAI internals;
update this call to pass stacklevel=2 so the emitted warning points to the
user's call site (i.e., change the warnings.warn call inside the
LoadImage.__init__ method to include stacklevel=2).

Source: Linters/SAST tools

self.register(the_reader())
try:
self.register(the_reader())
except OptionalImportError as e:
raise OptionalImportError(
f"required package for reader {_r} is not installed, or the version doesn't match requirement."
) from e
elif inspect.isclass(_r):
self.register(_r(*args, **kwargs))
else:
Expand Down
14 changes: 12 additions & 2 deletions tests/data/test_image_rw.py
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Original file line number Diff line number Diff line change
Expand Up @@ -139,8 +139,18 @@ def test_rgb(self, reader, writer):
class TestRegRes(unittest.TestCase):
def test_0_default(self):
self.assertTrue(len(resolve_writer(".png")) > 0, "has png writer")
self.assertTrue(len(resolve_writer(".nrrd")) > 0, "has nrrd writer")
self.assertTrue(len(resolve_writer("unknown")) > 0, "has writer")
_, has_nibabel = optional_import("nibabel")
_, has_itk = optional_import("itk", allow_namespace_pkg=True)
if has_nibabel or has_itk:
self.assertTrue(len(resolve_writer(".nrrd")) > 0, "has nrrd writer")
self.assertTrue(len(resolve_writer("unknown")) > 0, "has writer")
else:
with self.assertRaises(OptionalImportError) as ctx:
resolve_writer(".nrrd")
self.assertIn("Please install: itk or nibabel.", str(ctx.exception))
with self.assertRaises(OptionalImportError) as ctx:
resolve_writer("unknown")
self.assertIn("Please install: itk or nibabel.", str(ctx.exception))
register_writer("unknown1", lambda: (_ for _ in ()).throw(OptionalImportError))
with self.assertRaises(OptionalImportError):
resolve_writer("unknown1")
Expand Down
23 changes: 21 additions & 2 deletions tests/data/test_init_reader.py
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Original file line number Diff line number Diff line change
Expand Up @@ -29,9 +29,28 @@ def test_load_image(self):
self.assertIsInstance(instance1, LoadImage)
self.assertIsInstance(instance2, LoadImage)

from monai.utils import optional_import, OptionalImportError
pkg_map = {
"NibabelReader": "nibabel",
"PILReader": "PIL",
"ITKReader": "itk",
"NrrdReader": "nrrd",
"NumpyReader": "numpy",
"PydicomReader": "pydicom",
}
for r in ["NibabelReader", "PILReader", "ITKReader", "NumpyReader", "NrrdReader", "PydicomReader", None]:
inst = LoadImaged("image", reader=r)
self.assertIsInstance(inst, LoadImaged)
if r is None:
inst = LoadImaged("image", reader=r)
self.assertIsInstance(inst, LoadImaged)
continue

_, has_pkg = optional_import(pkg_map[r])
if has_pkg:
inst = LoadImaged("image", reader=r)
self.assertIsInstance(inst, LoadImaged)
else:
with self.assertRaises(OptionalImportError):
LoadImaged("image", reader=r)
Comment on lines +47 to +53

@coderabbitai coderabbitai Bot Jun 12, 2026

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⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
rg -n --type=py 'optional_import\("itk"' -C2

Repository: Project-MONAI/MONAI

Length of output: 5327

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Inspect the exact code under review
sed -n '1,140p' tests/data/test_init_reader.py | nl -ba | sed -n '35,90p'

# Find the pkg_map definition / ITKReader mapping and the exact optional_import call site
rg -n "pkg_map|ITKReader|LoadImaged|test_load_image|optional_import" tests/data/test_init_reader.py -n

# Inspect optional_import signature/docs in repo
optional_import_file="$(rg -n --type=py "def optional_import" -S . | head -n 1 | cut -d: -f1)"
echo "Found optional_import definition in: $optional_import_file"
sed -n '1,200p' "$optional_import_file" | nl -ba | sed -n '1,200p'

Repository: Project-MONAI/MONAI

Length of output: 106

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Show reviewed section with line numbers (no `nl` in this sandbox)
sed -n '1,120p' tests/data/test_init_reader.py | cat -n | sed -n '35,90p'

# Locate the exact test and the ITK probe line
rg -n "TestInitLoadImage|test_load_image|pkg_map|optional_import|ITKReader|LoadImaged" tests/data/test_init_reader.py

# Find optional_import implementation and show its signature/defaults
opt_file="$(rg -n --type=py "def optional_import" -S . | head -n 1 | cut -d: -f1)"
echo "optional_import definition: $opt_file"
sed -n '1,220p' "$opt_file" | cat -n | sed -n '1,220p'

Repository: Project-MONAI/MONAI

Length of output: 13955

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Get line number of optional_import definition
opt_def_line="$(rg -n --type=py "^def optional_import\\b" monai/utils/module.py | head -n 1 | cut -d: -f1)"
echo "optional_import def line: $opt_def_line"

# Print a window around the function start (signature + docstring header)
start=$((opt_def_line-20))
end=$((opt_def_line+120))
sed -n "${start},${end}p" monai/utils/module.py | cat -n

# Also find any occurrences of allow_namespace_pkg inside the function/file
rg -n "allow_namespace_pkg" monai/utils/module.py | head -n 50

Repository: Project-MONAI/MONAI

Length of output: 7091

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Find where ITKReader is resolved/used during LoadImaged/LoadImage
rg -n "ITKReader" monai -S
rg -n "LoadImaged\\(|LoadImage\\(" monai/transforms -S
rg -n "reader=.*ITKReader|resolve_reader|resolve_reader\\(|image_reader" monai -S

# Inspect relevant reader resolution code (likely monai/data/image_reader.py and monai/data/__init__.py / transforms loader)
sed -n '1,220p' monai/data/image_reader.py | cat -n

# Also inspect image_writer if needed (for writer mapping consistency)
sed -n '1,140p' monai/data/image_writer.py | cat -n

Repository: Project-MONAI/MONAI

Length of output: 21170

🏁 Script executed:

#!/bin/bash
set -euo pipefail

rg -n --type=py "^def require_pkg\\b" monai/utils/module.py
req_file="monai/utils/module.py"

req_line="$(rg -n --type=py "^def require_pkg\\b" "$req_file" | head -n 1 | cut -d: -f1)"
echo "require_pkg def line: $req_line"

start=$((req_line-20))
end=$((req_line+220))
sed -n "${start},${end}p" "$req_file" | cat -n

# See whether allow_namespace_pkg is referenced inside require_pkg
rg -n "allow_namespace_pkg" "$req_file" | head -n 50

Repository: Project-MONAI/MONAI

Length of output: 10172

🏁 Script executed:

#!/bin/bash
set -euo pipefail
rg -n "has_itk|\\bitk\\b" monai/data/image_reader.py

Repository: Project-MONAI/MONAI

Length of output: 1442

Handle ITK as a namespace package in TestInitLoadImage.test_load_image

tests/data/test_init_reader.py:47 probes ITK with optional_import(pkg_map[r]) (defaults allow_namespace_pkg=False), but runtime monai/data/image_reader.py loads ITK with optional_import("itk", allow_namespace_pkg=True, so namespace-style ITK installs can make has_pkg false and cause a false OptionalImportError expectation.

  • Same mismatch likely applies to nrrd (runtime also uses allow_namespace_pkg=True there, but this test doesn’t special-case it).
Suggested change 
-            _, has_pkg = optional_import(pkg_map[r])
+            import_kwargs = {"allow_namespace_pkg": True} if pkg_map[r] == "itk" else {}
+            _, has_pkg = optional_import(pkg_map[r], **import_kwargs)
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
_, has_pkg = optional_import(pkg_map[r])
if has_pkg:
inst = LoadImaged("image", reader=r)
self.assertIsInstance(inst, LoadImaged)
else:
with self.assertRaises(OptionalImportError):
LoadImaged("image", reader=r)
import_kwargs = {"allow_namespace_pkg": True} if pkg_map[r] == "itk" else {}
_, has_pkg = optional_import(pkg_map[r], **import_kwargs)
if has_pkg:
inst = LoadImaged("image", reader=r)
self.assertIsInstance(inst, LoadImaged)
else:
with self.assertRaises(OptionalImportError):
LoadImaged("image", reader=r)
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@tests/data/test_init_reader.py` around lines 47 - 53,
TestInitLoadImage.test_load_image currently calls optional_import(pkg_map[r])
(defaulting allow_namespace_pkg=False) to set has_pkg, but runtime code imports
ITK (and NRRD) with optional_import(..., allow_namespace_pkg=True), causing
false negatives; update the test to call optional_import(pkg_map[r],
allow_namespace_pkg=True) when probing readers for "itk" and "nrrd" (or set
allow_namespace_pkg=True for those pkg_map entries) so has_pkg matches the
runtime import behavior used by LoadImaged and the OptionalImportError
expectation is correct.


@SkipIfNoModule("nibabel")
@SkipIfNoModule("cupy")
Expand Down
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