dbstruct

Derive a database from a struct

This is an early release, the API is mostly stable but might still change

Create a typed embedded database by defining a struct. Interact with the database through getters and setters. Choose how values missing in the database are represented. Standard library types Vec, HashMap and Option have special getters and setters to mimic their standard library functionality. You can push and pop from vecs.

Choose out of various popular key-value databases then instantiate the struct providing only the db path. Alternatively pass any object that implements dbstruct::DataStore.

Use case

dbstruct is ideal when:

Writing a simple app that needs some form of persistence.
Quickly getting a storage layer done when developing a system that you can later replace.

Example

use std::path::Path;

#[dbstruct::dbstruct(db=sled)]
pub struct Test {
	#[dbstruct(Default)]
	the_awnser: u8,
	primes: Vec<u32>,
	#[dbstruct(Default="format!(\"{}\", 20+2+20)")]
	the_result: String,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
	// a wrapper around a HashMap that implements the 
	// `DataStore` trait
    let path_to_dir = tempdir::TempDir::new("readme_example")?;
	let db = Test::new(path_to_dir)?;

	db.the_awnser().set(&42)?;
	assert_eq!(42u8, db.the_awnser().get()?);

	db.primes().push(&2)?;
	db.primes().push(&3)?;
	db.primes().push(&5)?;
    db.primes().push(&7)?;
    assert_eq!(Some(7), db.primes().pop()?);

    assert_eq!(String::from("42"), db.the_result().get()?);
    Ok(())
}

Out of the box support

Name	advantage	attribute option
Sled	pure Rust	`db=sled`
BTreeMap, does not store anything!	testing	`db=btreemap`

work in progress: rocksdb

Future Work

These are some features I am planning to work on, in no particular order. If you miss anything please let me know via an issue!

Example workflow for migrations.
Allow access from multiple threads cloning the struct
Flushing the database, explicitly via a function on the struct and implicitly whenever a field changes. Will be configurable through an attribute on the struct and a field specifically.
Expand the wrapper API to more closely match that of their standard library counterparts.
Async support for flushing the database.
Figure out how to represent transactions (hard if even possible)

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