`uv Pip Compile` Generates An Invalid `pyproject.toml` (uses Requirements.txt Format Instead Of TOML)

uv pip compile generates an invalid pyproject.toml (uses requirements.txt format instead of TOML)

Summary

When running uv pip compile -o pyproject.toml requirements.txt, the generated pyproject.toml is not in valid TOML format. Instead, it follows the requirements.txt format, which causes parsing errors when trying to use uv for dependency management.

Description

The uv pip compile command is used to generate a pyproject.toml file from a requirements.txt file. However, when this command is run, the generated pyproject.toml file does not follow the proper TOML format. Instead, it contains a list of dependencies in the format of package==version, which is similar to the requirements.txt format.

This issue can cause problems when trying to use uv for dependency management, as the pyproject.toml file is not in a format that can be parsed by uv.

Steps to Reproduce

To reproduce this issue, follow these steps:

1. Prepare a requirements.txt file with the following content:

aiohappyeyeballs2.6.1 aiohttp3.11.16 aiosignal==1.3.2

2. Run the `uv` command to generate `pyproject.toml`:
   ```bash
uv pip compile -o pyproject.toml requirements.txt

3. Open the generated pyproject.toml file. Instead of a proper TOML structure, it contains:

aiohappyeyeballs2.6.1 # via aiohttp aiohttp3.11.16 # via py-cord aiosignal==1.3.2 # via aiohttp

4. Try to install dependencies using `uv pip install -r pyproject.toml`. It results in the following error:
   ```bash
TOML parse error at line 3, column 18
invalid string
expected `"`, `'`

Expected Behavior

The generated pyproject.toml should follow the proper TOML format, like this:

[project]
name = "my_project"
version = "0.1.0"
description = "My Project Description"
dependencies = [
 "aiohappyeyeballs==2.6.1",
 "aiohttp==3.11.16",
 "aiosignal==1.3.2",
]

Workarounds

If you need to generate a proper pyproject.toml file, you can use the following workarounds:

1. Use pip-compile instead of uv pip compile: You can use the pip-compile command from the pip-tools package to generate a pyproject.toml file. This command will generate a pyproject.toml file in the proper TOML format.

pip install pip-tools pip-compile requirements.txt -o pyproject.toml

2. **Use a different tool to generate `pyproject.toml`**: There are other tools available that can generate a `pyproject.toml` file in the properL format. For example, you can use the `poetry` package to generate a `pyproject.toml` file.
   ```bash
poetry init
poetry add aiohappyeyeballs aiohttp aiosignal
poetry export -f pyproject.toml

Platform

This issue was reproduced on macOS M1.

Version

The version of uv used to reproduce this issue is 0.6.12 (Homebrew 2025-04-02).

Python version

The Python version used to reproduce this issue is Python 3.12.9.

Conclusion

The uv pip compile command generates an invalid pyproject.toml file when run with a requirements.txt file. This issue causes parsing errors when trying to use uv for dependency management. To work around this issue, you can use the pip-compile command from the pip-tools package or a different tool to generate a pyproject.toml file in the proper TOML format.
uv pip compile generates an invalid pyproject.toml (uses requirements.txt format instead of TOML)

Q&A

Q: What is the issue with the uv pip compile command?

A: The uv pip compile command generates an invalid pyproject.toml file when run with a requirements.txt file. The generated pyproject.toml file does not follow the proper TOML format, which causes parsing errors when trying to use uv for dependency management.

Q: What is the expected behavior of the uv pip compile command?

A: The expected behavior of the uv pip compile command is to generate a pyproject.toml file in the proper TOML format. This file should contain the dependencies listed in the requirements.txt file, along with other metadata such as the project name, version, and description.

Q: How can I reproduce this issue?

A: To reproduce this issue, follow these steps:

1. Prepare a requirements.txt file with the following content:

aiohappyeyeballs2.6.1 aiohttp3.11.16 aiosignal==1.3.2

2. Run the `uv` command to generate `pyproject.toml`:
   ```bash
uv pip compile -o pyproject.toml requirements.txt

3. Open the generated pyproject.toml file. Instead of a proper TOML structure, it contains:

aiohappyeyeballs2.6.1 # via aiohttp aiohttp3.11.16 # via py-cord aiosignal==1.3.2 # via aiohttp

4. Try to install dependencies using `uv pip install -r pyproject.toml`. It results in the following error:
   ```bash
TOML parse error at line 3, column 18
invalid string
expected `"`, `'`

Q: What are the workarounds for this issue?

A: There are two workarounds for this issue:

1. Use pip-compile instead of uv pip compile: You can use the pip-compile command from the pip-tools package to generate a pyproject.toml file. This command will generate a pyproject.toml file in the proper TOML format.

pip install pip-tools pip-compile requirements.txt -o pyproject.toml

2. **Use a different tool to generate `pyproject.toml`**: There are other tools available that can generate a `pyproject.toml` file in the proper TOML format. For example, you can use the `poetry` package to generate a `pyproject.toml` file.
   ```bash
poetry init
poetry add aiohappyeyeballs aiohttp aiosignal
poetry export -f pyproject.toml

Q: What is the platform and version of uv used to reproduce this issue?

A: This issue was reproduced on macOS M1 with uv version 0.6.12 (Homebrew 2025-04-02) and Python version .12.9.

Q: How can I contribute to this issue?

A: If you are experiencing this issue, you can contribute to it by providing more information about your environment and the steps you took to reproduce the issue. You can also try to fix the issue by submitting a pull request to the uv repository.