Py-Linq-SQL

A Python module used for interacting with sql database using LINQ syntax. The project is under EUPL License v1.2.

Py-linq-sql allows you to go from (SQLAlchemy using direct text query):

conn.execute(
  text(
    """SELECT "data"->'obj'->'name' as name """
    """FROM "objects" """
    """WHERE "data"->'obj'->>'name' == "earth" """
    """AND CAST("data"->'obj'->'mass' > 0.5 AS Decimal) """
    """LIMIT 1 OFFSET 2"""
  )
)

to the safer and easier to read:

sqle = (
  SQLEnumerable(conn, "objects")  # objects is the name of the table
  .select(lambda x: {"name": x.data.obj.name})  # data is a JSONB column
  .where(lambda x: x.data.obj.mass > 0.5)  # data is a JSONB column
  .skip(2)
  .take(1)  # this is the last part of the query, till there nothing is executed
  .execute()  # now we ask for the whole query to be executed on the DB server
)

Pro :

• all the query expression are expressed in pure python expression
• easy support of JSON database using a simple object notation
• very difficult to have an SQL injection (only the names of the tables are strings)
• standardized syntax/API of LINQ (used in java, C# and many .net languages)
• very fast: even very long and complex queries are executed in one single query on the server
• no need to define a class for every table in the DB as you would do in an ORM here you write query assuming the tables, columns and fields exist, if not then you get a clear error about it
• results are pylinq Enumerable that are themselves queryable in same way but locally
• all kinds of join (inner, outer and full, with or without intersections) are easy to use and combine with any kind of query

Cons :

• currently only support PostgresQL

Any feedback is welcome see Contributing.

Contacts

• Author: Ulysse CHOSSON (LESIA)
• Maintainer: Ulysse CHOSSON (LESIA)
• Email: ulysse.chosson@obspm.fr
• Contributors:
  • Pierre-Yves MARTIN (LESIA)

Table of Content

• Py-Linq-SQL
  • Contacts
  • Table of Content
  • Install
  • Implemented functions
    • LINQ functions
    • Custom functions
  • Not implemented functions
    • LINQ functions
    • Py-Linq functions
  • Contributing and info for developers
  • Full documentation

Install

For all specific commands to this project, we use just. You need to install it.

After you can install the dependencies:

$ just install
pwd
/home/uchosson/Documents/py-linq-sql
poetry install --no-dev --remove-untracked
Installing dependencies from lock file
Warning: The lock file is not up to date with the latest changes in pyproject.toml.
You may be getting outdated dependencies. Run update to update them.

No dependencies to install or update

Installing the current project: py-linq-sql (0.109.0)

And if you need to develop the project, install development dependencies:

$ just install-all
pwd
/home/uchosson/Documents/py-linq-sql
poetry install --remove-untracked
Installing dependencies from lock file
Warning: The lock file is not up to date with the latest changes in pyproject.toml.
You may be getting outdated dependencies. Run update to update them.

No dependencies to install or update

Installing the current project: py-linq-sql (0.109.0)
npm install

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sudo npm install markdownlint-cli2 --global

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found 0 vulnerabilities

and the pre-commit dependencies:

$ just preinstall
pwd
/home/uchosson/Documents/py-linq-sql
pre-commit clean
Cleaned /home/uchosson/.cache/pre-commit.
pre-commit autoupdate
Updating https://github.com/pre-commit/pre-commit-hooks ...
[INFO] Initializing environment for https://github.com/pre-commit/pre-commit-hooks.
already up to date.
Updating https://github.com/pre-commit/pre-commit-hooks ... already up to date.
Updating https://github.com/pycqa/isort ...
[INFO] Initializing environment for https://github.com/pycqa/isort.
already up to date.
Updating https://github.com/ambv/black ...
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already up to date.
Updating https://github.com/codespell-project/codespell ...
[INFO] Initializing environment for https://github.com/codespell-project/codespell.
already up to date.
Updating https://github.com/sqlfluff/sqlfluff ...
[INFO] Initializing environment for https://github.com/sqlfluff/sqlfluff.
updating 1.1.0 -> 1.2.1.
Updating https://github.com/pycqa/flake8 ...
[INFO] Initializing environment for https://github.com/pycqa/flake8.
already up to date.
Updating https://github.com/DavidAnson/markdownlint-cli2 ...
[INFO] Initializing environment for https://github.com/DavidAnson/markdownlint-cli2.
already up to date.
pre-commit install --hook-type pre-merge-commit
pre-commit installed at .git/hooks/pre-merge-commit
pre-commit install --hook-type pre-push
pre-commit installed at .git/hooks/pre-push
pre-commit install --hook-type post-rewrite
pre-commit installed at .git/hooks/post-rewrite
pre-commit install-hooks
[INFO] Installing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/pycqa/isort.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/ambv/black.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/codespell-project/codespell.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/sqlfluff/sqlfluff.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/pycqa/flake8.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/DavidAnson/markdownlint-cli2.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
pre-commit install
pre-commit installed at .git/hooks/pre-commit

Implemented functions

LINQ functions

LINQ documentation

All function make before an .execute() are executed by the database server.

MDPA = MagicDotPathAggregate

For more information see the detailed documentation.

Custom functions

Not implemented functions

LINQ functions

Py-Linq functions

Py-Linq link

Contributing and info for developers

• Changelog
• Contributing
• Our git workflow

Full documentation

• Py-LINQ-SQL Documentation