gelx

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

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 = "0.3"

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 types 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 gelx::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(())
}

Configuration

The following configuration options are supported.

[package.metadata.gelx]
## The location of the queries relative to the root of the crate.
queries = "./queries"

## The features to enable and their aliases. By default all features are enabled.
## To disable a feature set it to false. The available features are:
## - query
## - serde
## - strum
## - builder
features = { query = "ssr", strum = "ssr", builder = "ssr" }

## The location of the generated code when using the `gelx` cli.
output_file = "./src/gelx_generated.rs"

## The name of the arguments input struct. Will be transformed to PascalCase.
input_struct_name = "Input"

## The name of the exported output struct for generated queries. Will be transformed to PascalCase.
output_struct_name = "Output"

## The name of the query function exported.
query_function_name = "query"

## The name of the transaction function exported.
transaction_function_name = "transaction"

## The relative path to the `gel` config file. This is optional and if not provided the `gel`
## config will be read from the environment variables.
# gel_config_path = "./gel.toml"

## The name of the `gel` instance to use. This is optional and if not provided the environment
## variable `$GEL_INSTANCE` will be used.
# gel_instance = "$GEL_INSTANCE"

## The name of the `gel` branch to use. This is optional and if not provided the environment
## variable `$GEL_BRANCH` will be used.
# gel_branch = "$GEL_BRANCH"

CLI

The gelx_cli crate exposes a binary called gelx which can be used to generate the typed code into rust files rather than inline queries.

It should be run from the crate directory and will read from the configuration specified in the previous section.

cd path/to/crate
gelx generate

Sometimes you will need to check that the generated code matches the current database schema and queries generated by gel. This is useful for CI pipelines.

gelx check

If there are changes that haven't been accounted for, the check will fail and you should regenerate the code.

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:

• MultiRange - The macro will panic if a multirange is used.

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.

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 {**}
);

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.
• strum - Use the strum crate for deriving strings from the created enums.