Crate magnet_schema

Magnet, a JSON/BSON schema generator.

These two related crates, magnet_schema and magnet_derive define a trait, BsonSchema, and a proc-macro derive for the same trait, which allows types to easily implement JSON schema validation for use with MongoDB.

The trait defines a single function, bson_schema(), that returns a BSON Document describing the validation schema of the type based on its fields (for structs and tuples), variants (for enums), or elements/entries (for array- and map-like types).

The types are expected to be serialized and deserialized using Serde, and generally Magnet will try very hard to respect #[serde(...)] annotations as faithfully as possible, but no Serialize + Deserialize trait bounds are enforced on the types as this is not strictly necessary.

Example usage:

#[macro_use]
extern crate bson;
#[macro_use]
extern crate magnet_derive;
extern crate magnet_schema;

use std::collections::HashMap;
use magnet_schema::BsonSchema;

#[derive(BsonSchema)]
struct Animal {
    age_months: usize,
    species_name: &'static str,
    subspecies_endangered: HashMap<String, bool>,
}

fn main() {
    let schema_doc = Animal::bson_schema();
    println!("{:#?}", schema_doc);
}

Roadmap:

• [x] Define BsonSchema trait

• [x] impl BsonSchema for most primitives/std:: types

• [ ] Cargo features for implementing BsonSchema for "atomic" types in foreign crates, for instance, hyper::Url and uuid::Uuid.

• [x] #[derive(BsonSchema)] on regular, named-field structs

• [ ] #[derive(BsonSchema)] on tuple structs

• [x] #[derive(BsonSchema)] on unit structs

• [ ] #[derive(BsonSchema)] on enums

  • [ ] unit variants

  • [ ] newtype/tuple variants

  • [ ] struct variants

  • [ ] respect Serde tagging conventions: external/internal/adjacent

• [ ] In top-level documents, allow specification of an ID/"primary key" field which will map from/to _id only when the JSON schema is generated (and not during normal value de/serialization).

• [ ] Respect more #[serde(...)] attributes, for example: rename, rename_all, skip, etc.

• [ ] Handle generic types in proc-macro derive

• [ ] Standard (non-MongoDB-specific) JSON schema support (approach?)

• [ ] UNIT TESTS!!!

• [ ] impl BsonSchema for more esoteric primitives/standard types such as specialization of [u8]/Vec<u8> as binary, adding a validation regex "pattern" to Path and PathBuf, etc.

• [ ] Add our own attributes if necessary?

Traits

BsonSchema

Types which can be expressed/validated by a MongoDB-flavored JSON schema.