reed-compiler 0.1.2

A compiler for the GraphQL query language.
Documentation

Features

  • A (comparatively) low-level AST for GraphQL grammar, and high-level representation of Schema and ExecutableDocument.
  • All three can be parsed (using reed-parser internally), created or modified programatically, and serialized.
  • Validation of schemas and executable documents, as defined in the GraphQL specification.
  • Execution of the schema introspection portion of queries.

Getting started

Add the dependency to start using reed-compiler:

cargo add reed-compiler

Or add this to your Cargo.toml for a manual installation:

# Just an example, change to the necessary package version.
[dependencies]
reed-compiler = "0.1.0"

Rust versions

reed-compiler is tested on the latest stable version of Rust. Older version may or may not be compatible.

Usage

You can get started with reed-compiler:

use reed_compiler::Schema;
use reed_compiler::ExecutableDocument;

let sdl = r#"
  type Query {
    field: Int
  }
"#;
let query = "{ field }";

/// In case of validation errors, the panic message will be nicely formatted
/// to point at relevant parts of the source file(s)
let schema = Schema::parse_and_validate(sdl, "sdl.graphql").unwrap();
let doc = ExecutableDocument::parse_and_validate(&schema, query, "query.graphql").unwrap();

Examples

Accessing fragment definition field types

use reed_compiler::{Schema, ExecutableDocument, Node, executable};

let schema_input = r#"
type User {
  id: ID
  name: String
  profilePic(size: Int): URL
}

schema { query: User }

scalar URL @specifiedBy(url: "https://tools.ietf.org/html/rfc3986")
"#;
let query_input = r#"
query getUser {
  ... vipCustomer
}

#fragment definition where we want to know the field types.
fragment vipCustomer on User {
  id
  name
  profilePic(size: 50)
}
"#;

let schema = Schema::parse_and_validate(schema_input, "schema.graphql").unwrap();
let document = ExecutableDocument::parse_and_validate(&schema, query_input, "query.graphql")
    .unwrap();

let op = document.operations.get(Some("getUser")).expect("getUser query does not exist");
let fragment_in_op = op.selection_set.selections.iter().filter_map(|sel| match sel {
    executable::Selection::FragmentSpread(spread) => {
        Some(document.fragments.get(&spread.fragment_name)?.as_ref())
    }
    _ => None
}).collect::<Vec<&executable::Fragment>>();

let fragment_fields = fragment_in_op.iter().flat_map(|frag| {
    frag.selection_set.fields()
}).collect::<Vec<&Node<executable::Field>>>();
let field_ty = fragment_fields
    .iter()
    .map(|f| f.ty().inner_named_type().as_str())
    .collect::<Vec<&str>>();
assert_eq!(field_ty, ["ID", "String", "URL"]);

Get a directive defined on a field used in a query operation definition.

use reed_compiler::{Schema, ExecutableDocument, Node, executable};

let schema_input = r#"
type Query {
  topProducts: Product
}

type Product {
  inStock: Boolean @join__field(graph: INVENTORY)
  name: String @join__field(graph: PRODUCTS)
}

enum join__Graph {
  INVENTORY,
  PRODUCTS,
}
directive @join__field(graph: join__Graph) on FIELD_DEFINITION
"#;
let query_input = r#"
query getProduct {
  topProducts {
    inStock
  }
}
"#;

let schema = Schema::parse_and_validate(schema_input, "schema.graphql").unwrap();
let document = ExecutableDocument::parse_and_validate(&schema, query_input, "query.graphql")
    .unwrap();

let get_product_op = document
    .operations
    .get(Some("getProduct"))
    .expect("getProduct query does not exist");

let in_stock_field = &get_product_op
    .selection_set
    .fields()
    .find(|f| f.name == "topProducts")
    .expect("topProducts field does not exist")
    .selection_set
    .fields()
    .find(|f| f.name == "inStock")
    .expect("inStock field does not exist")
    .definition;
let in_stock_directive: Vec<_> = in_stock_field
    .directives
    .iter()
    .map(|dir| &dir.name)
    .collect();
assert_eq!(in_stock_directive, ["join__field"]);

Printing diagnostics for a faulty GraphQL document

use reed_compiler::parser::Parser;

let input = "{ ... }";

if let Err(diagnostics) = Parser::new().parse_mixed_validate(input, "document.graphql") {
    println!("{diagnostics}")
}

License

Licensed under either of

at your option.

Upstream provenance

Reed Compiler 0.1.0 is derived from Apollo Compiler 1.33.0 at upstream revision 5ebcc40bdf6919843c122e9a76b241689edcd6ef. The source corrections used to establish Reed are maintained in this crate and its regression tests. Package and crate paths, the parser dependency, documentation, workspace rustfmt layout, and regression tests are adapted for Reed; the compiler public API and module organization are retained.