gelx

Generate fully typed rust code from your gel schema and inline queries.

Installation

To install the gelx crate you can use the following command.

cargo add gelx

Or directly add the following to your Cargo.toml file.

gelx = "0.2"

Follow the Quickstart Guide to make sure your gel instance is running. The macro relies on the running gel instance to parse the output of the provided query string.

Usage

When working with gel you often need to write queries and also provide the typed for both the input and output. Your code is only checked at runtime which increases the risk of bugs and errors.

Fortunately, gel has a query language that is typed and can be converted into types and queried for correctness at compile time.

Inline Queries

use gel_errors::Error;
use gel_tokio::create_client;
use gelx::gelx;

// Creates a module called `simple` with a function called `query` and structs
// for the `Input` and `Output`.
gelx!(
	simple,
	"select { hello := \"world\", custom := <str>$custom }"
);

#[tokio::main]
async fn main() -> Result<(), Error> {
	let client = create_client().await?;
	let input = simple::Input {
		custom: String::from("custom"),
	};

	// For queries the following code can be used.
	let output = simple::query(&client, &input).await?;

	Ok(())
}

The macro above generates the following code:

pub mod simple {
	use ::gelx::exports as e;
	/// Execute the desired query.
	#[cfg(feature = "query")]
	pub async fn query(
		client: &e::gel_tokio::Client,
		props: &Input,
	) -> core::result::Result<Output, e::gel_errors::Error> {
		client.query_required_single(QUERY, props).await
	}
	/// Compose the query as part of a larger transaction.
	#[cfg(feature = "query")]
	pub async fn transaction(
		conn: &mut e::gel_tokio::Transaction,
		props: &Input,
	) -> core::result::Result<Output, e::gel_errors::Error> {
		conn.query_required_single(QUERY, props).await
	}
	#[derive(Clone, Debug)]
	#[cfg_attr(feature = "builder", derive(e::typed_builder::TypedBuilder))]
	#[cfg_attr(feature = "query", derive(e::gel_derive::Queryable))]
	#[cfg_attr(feature = "serde", derive(e::serde::Serialize, e::serde::Deserialize))]
	pub struct Input {
		#[cfg_attr(feature = "builder", builder(setter(into)))]
		pub custom: String,
	}
	impl e::gel_protocol::query_arg::QueryArgs for Input {
		fn encode(
			&self,
			encoder: &mut e::gel_protocol::query_arg::Encoder,
		) -> core::result::Result<(), e::gel_errors::Error> {
			let map = e::gel_protocol::named_args! {
				"custom" => self.custom.clone(),
			};
			map.encode(encoder)
		}
	}
	#[derive(Clone, Debug)]
	#[cfg_attr(feature = "query", derive(e::gel_derive::Queryable))]
	#[cfg_attr(feature = "serde", derive(e::serde::Serialize, e::serde::Deserialize))]
	pub struct Output {
		pub hello: String,
		pub custom: String,
	}
	/// The original query string provided to the macro. Can be reused in your
	/// codebase.
	pub const QUERY: &str = "select { hello := \"world\", custom := <str>$custom }";
}

Query Files

Define a query file in the queries directory of your crate called select_user.edgeql.

# queries/select_user.edgeql

select User {
  name,
  bio,
  slug,
} filter .slug = <str>$slug;

Then use the gelx macro to import the query.

use gel_errors::Error;
use gel_tokio::create_client;
use gelx::gelx;

// Creates a module called `select_user` with public functions `transaction` and
// `query` as well as structs for the `Input` and `Output`.
gelx!(select_user);

#[tokio::main]
async fn main() -> Result<(), Error> {
	let client = create_client().await?;

	// Generated code can be run inside a transaction.
	let result = client
		.transaction(|mut txn| {
			async move {
				let input = select_user::Input {
					slug: String::from("test"),
				};
				let output = select_user::transaction(&mut txn, &input).await?;
				Ok(output)
			}
		})
		.await?;

	Ok(())
}

Future Work

This crate is still in early development and there are several features that are not yet implemented.

Missing Types

Currently the following types are not supported:

• enum - currently all enums are represented as strings.
• MultiRange - The macro will panic if a multirange is used.

enum

Currently all enums are represented as strings.

In order to support full enum generation the gel-protocol crate needs to be updated to use the binary protocol 2.0. In the current 1.0 version the enum descriptors are returned without the name property.

Once this is implemented the macro will be able to generate the correct code.

However end users probably don't want multiple enums for each generated query module as this would break sharing. To get around this, there should be a macro for generating the shared types used by all other.

// lib.rs
use gelx::generate_shared_types;

generate_shared_types!(); // exports the shared types to the `edb` module.

MultiRange

These are not currently exported by the gel-protocol so should be added in a PR to the gel-protocol crate, if they are still supported in the new protocol.

Configuration

Currently everything is hardcoded and the macro is not configurable.

The following configuration options should be added:

• Name of input struct (optional) - Input by default.
• Name of output struct (optional) - Output by default.
• Name of query function (optional) - query by default.
• Name of transaction function (optional) - transactionby default.
• Default location of queries (optional) - queries by default.
• Default crate export name for shared types (optional) - edb by default.
• Default gel instance (optional) - $GEL_INSTANCE by default.
• Default gel branch (optional) - $GEL_BRANCH by default.

Probably these should be read from the Cargo.toml file and parsed manually to prevent slowdowns from parsing the file.

LSP parsing

Currently the macro depends on having a running gel instance to parse the query string.

Once an LSP is created for gel it would make sense to switch from using string to using inline gel queries.

use gelx::gelx;

gelx!(
	example,
	select User {**}
);

CLI

Create a gelx_cli crate which supports generating the typed code into rust files rather than inline queries. This is useful for larger projects to prevent constantly compiling the queries on every change / build.

Features

• default — The default feature is with_all.
• with_bigint — Include the num-bigint dependency.
• with_bigdecimal — Use the bigdecimal crate.
• with_chrono — Use the chrono crate for all dates.
• with_all (enabled by default) — Include all additional types. This is included by default. Use default-features = false to disable.
• builder — Use the typed-builder crate to generate the builders for the generated Input structs.
• query — Turn on the query and transaction methods and anything that relies on gel-tokio. The reason to separate this feature is to enable usage of this macro in browser environments where gel-tokio is not feasible.
• serde — Enable serde for the generated code.