PyLance in Visual Studio Code does not recognise Poetry virtual env dependencies

Question

I am using Poetry to manage a Python project. I create a virtual environment for Poetry using a normal poetry install and pyproject.toml workflow. Visual Studio Code and its PyLance does not pick up project dependencies in Jupyter Notebook.

• Python stdlib modules are recognised
• The modules of my application are recognised
• The modules in the dependencies and libraries my application uses are not recognised

Instead, you get an error

Import "xxx" could not be resolved Pylance (reportMissingImports)

An example screenshot with some random imports that show what is recognised and what is not (tradeexecutor package is Poetry project, then some random Python packages dependency are not recognised).:

The notebook still runs fine within Visual Studio Code, so the problem is specific to PyLance, the virtual environment is definitely correctly set up.

Some Python Language Server output (if relevant):

2024-03-01 10:15:40.628 [info] [Info  - 10:15:40] (28928) Starting service instance "trade-executor"
2024-03-01 10:15:40.656 [info] [Info  - 10:15:40] (28928) Setting pythonPath for service "trade-executor": "/Users/moo/code/ts/trade-executor"
2024-03-01 10:15:40.657 [info] [Info  - 10:15:40] (28928) Setting environmentName for service "trade-executor": "3.10.13 (trade-executor-8Oz1GdY1-py3.10 venv)"
2024-03-01 10:15:40.657 [info] [Info  - 10:15:40] (28928) Loading pyproject.toml file at /Users/moo/code/ts/trade-executor/pyproject.toml
2024-03-01 10:15:40.657 [info] [Info  - 10:15:40] (28928) Pyproject file "/Users/moo/code/ts/trade-executor/pyproject.toml" has no "[tool.pyright]" section.
2024-03-01 10:15:41.064 [info] [Info  - 10:15:41] (28928) Found 763 source files
2024-03-01 10:15:41.158 [info] [Info  - 10:15:41] (28928) Background analysis(4) root directory: file:///Users/moo/.vscode/extensions/ms-python.vscode-pylance-2024.2.2/dist
2024-03-01 10:15:41.158 [info] [Info  - 10:15:41] (28928) Background analysis(4) started
2024-03-01 10:15:41.411 [info] [Info  - 10:15:41] (28928) Indexer background runner(5) root directory: file:///Users/moo/.vscode/extensions/ms-python.vscode-pylance-2024.2.2/dist (index)
2024-03-01 10:15:41.411 [info] [Info  - 10:15:41] (28928) Indexing(5) started
2024-03-01 10:15:41.662 [info] [Info  - 10:15:41] (28928) scanned(5) 1 files over 1 exec env
2024-03-01 10:15:42.326 [info] [Info  - 10:15:42] (28928) indexed(5) 1 files over 1 exec

Also looks like PyLance correctly finds the virtual environment in the earlier Python Language Server output:

2024-03-03 19:36:56.784 [info] [Info  - 19:36:56] (41658) Pylance language server 2024.2.2 (pyright version 1.1.348, commit cfb1de0c) starting
2024-03-03 19:36:56.789 [info] [Info  - 19:36:56] (41658) Server root directory: file:///Users/moo/.vscode/extensions/ms-python.vscode-pylance-2024.2.2/dist
2024-03-03 19:36:56.789 [info] [Info  - 19:36:56] (41658) Starting service instance "trade-executor"
2024-03-03 19:36:57.091 [info] [Info  - 19:36:57] (41658) Setting pythonPath for service "trade-executor": "/Users/moo/Library/Caches/pypoetry/virtualenvs/trade-executor-8Oz1GdY1-py3.10/bin/python"
2024-03-03 19:36:57.093 [info] [Info  - 19:36:57] (41658) Setting environmentName for service "trade-executor": "3.10.13 (trade-executor-8Oz1GdY1-py3.10 venv)"
2024-03-03 19:36:57.096 [info] [Info  - 19:36:57] (41658) Loading pyproject.toml file at /Users/moo/code/ts/trade-executor/pyproject.toml

How to diagnose the issue further and then fix the issue?

Answer 1

For me I was able to resolve this by selecting the interpreter in VSCode that matched the path. This was actually not the recommended interpreter so it was not the most intuitive.

I ran ctrl, shift, p to open the palette and then up above chose the interpreter that had been created for my project specifically and not the global.

This has been a problem for two projects so far so I assume it is fairly common. This fixed my error both times.

Answer 2

Here is another answer on when Jupyter Notebook, Visual Studio Code and Poetry fail:

If you use pyproject.toml with Poetry's develop = true feature, It just does not work, as Visual Studio Code and Pylance does not support it.

• I tried manually force Pylance to scan the packages through various settings, but Pylance still refused to scan the packages

Here is the pyproject.toml workaround:

#
# TODO: It's very hard to make local dev env to have trade-executor
# editable dependency with Poetry at the moment.
# Thus we assume is that if you install yourself, you have cloned
# trade-executor to ../trade-executor path.
# Or change the line below.
#
# Poetry develop = true and Visual Studio Code bug https://github.com/microsoft/pylance-release/issues/4664
#
[tool.poetry.dependencies]
python = ">=3.10,<3.12"
trade-executor = {path = "../trade-executor", develop = false, extras=["execution", "quantstats"]}
ipython = "^8.12.0"
ipdb = "^0.13.13"
parquet-cli = "^1.3"

Answer 3

Some other people were having the same issue.

• Pylance does not show auto import information from site-packages directory #3281
• Pylance not indexing all files and symbols for sqlalchemy even with package depth of 4

Visual Studio Code's PyLance implementation seems to have some internal limits that may prevent indexing all files. However, this was not the case for me. Instead, PyLance was somehow corrupted.

Running: PyLance: Clear all persistent indices from the command palette fixed the issue for. After this, PyLance seemed to behave.