Parrot – type-safe SQL in Gleam, supports SQlite, PostgreSQL and MySQL

1 month ago 9

🚨 Exciting News
Parrot got listed a community project on the sqlc website! 🦜🎉
Check it out here: https://docs.sqlc.dev/en/latest/reference/language-support.html

🦜 Parrot / type-safe SQL in gleam

Table of contents generated with markdown-toc

Most of the heavy lifting features are provided by / built into sqlc, I do not aim to take credit for them.

☑️ Supports SQlite, PostgreSQL and MySQL.
☑️ Multiple queries per file.
☑️ Database client agnostic.
☑️ Utility wrappers for popular gleam database libraries (lpil/sqlight, lpil/pog).
☑️ Automatically pulls the schema of your database.
☑️ Automatically downloads sqlc binary.
☑️ Named parameters.^*1

^*1: Meaning that it infers the names of the parameters from your sql queries in the gleam function you call. for example for a query called FindUser, defined as SELECT * FROM user WHERE username = $1, parrot will produce a function where the arguments match those column names: pub fn find_user(username: String) { ... }. If you have multiple parameters of the same data types this can avoid confusion and bugs.

Parrot will look for all *.sql files in any sql directory under your project's src directory.
Each *.sql file can contain as many SQL queries as you want.
All of the queries will compile into a single src/[project name]/sql.gleam module.

Here are some links to help you start out, if you are unfamiliar with the sqlc annotation syntax:

Here is an example of the file structure:

├── gleam.toml ├── README.md ├── src │ ├── app.gleam │ └── sql │ ├── auth.sql │ └── posts.sql └── test └── app_test.gleam

# automatically detects database & engine from env (DATABASE_URL by default) $ gleam run -m parrot # provide connection string from different environment variable $ gleam run -m parrot -- -e PG_DATABASE_URL # specify sqlite file $ gleam run -m parrot -- --sqlite <file_path> # see all options $ gleam run -m parrot help

If you use SQLite, you also need to have installed sqlite3.

If you use MySQL, you also need to have installed mysqldump (comes by default if you have a mysql client installed).

If you use PostgreSQL, you also need to have installed pg_dump (comes by default if you have a postgresql client installed).

You now have type safe access to your sql queries.

You might want to write wrapper functions for the database client library of your choice. If you are using lpil/pog or lpil/sqlight, you are in luck! You can find functions to copy & paste into your codebase here: wrappers

An example with lpil/sqlight:

import app/sql import parrot/dev fn parrot_to_sqlight(param: dev.Param) -> sqlight.Value { // ... } pub fn main() { // ... let #(sql, with, expecting) = sql.get_user_by_username("alice") let with = parrot_to_sqlight(with) let row = sqlight.query(sql, on:, with:, expecting:) // ... }

If you want to see how this library works in action, take a look at the integration tests:

just is used to run project commands.

There are scripts to spawn a MySQL or PostgreSQL docker container:

For example:

$ ./bin/mysql.sh # or $ ./bin/psql.sh

$ just test-sqlite $ just test-mysql $ just test-psql

As with everything in software, there are some quirks with this library, due to the nature of your database of choice and sqlc.

If you have an INTEGER[][] column in Postgres, pg_dump does not correctly identify the column as a two-dimensional array and therefore only gives you a List(Int) instead of a List(List(Int)). If this is a problem for you, you can raise an issue and we might come up with a solution or workaround.

There are a couple of complex data types that are explictly made dynamic since they are too complex to handle with the current implementation. There is a plan for a better and more flexible implementation. Until then, it will be wrapped in a dynamic type.

So here is the catch: you can only execute parrot in an erlang gleam application. However the generated code will also run in a javascript environment. So if you need parrot for a javascript project, you can create a separate package and copy over the generated module and that will work.

What flavour of SQL does parrot support?

This library supports everything that sqlc supports. As the time of this writing that would be MySQL, PostgreSQL and SQlite.

You can read more on language & SQL support here: https://docs.sqlc.dev/en/stable/reference/language-support.html

What sqlc features are not supported?

embeddeding structs (https://docs.sqlc.dev/en/stable/howto/embedding.html)
Certain query annotations are not supported and will panic the process: :execrows, :execlastid, :batchexec, :batchone, :batchmany, :copyfrom. You can read more about it here: https://docs.sqlc.dev/en/stable/reference/query-annotations.html

Ideas and actionable tasks are collected and organised here: https://github.com/daniellionel01/parrot/issues

Contributions are welcomed!