graphql-idl-parser

A parser for GraphQL IDL files! This repository contains the code for both the Rust implementation, as well as the FFI dylib implementation, which allows you to generate a library for use in C projects (and other languages that play nice with C). See https://github.com/gjtorikian/graphql-idl-parser-ruby for a Ruby implementation!

Why?

Two reasons:

I have plenty of experience doing Bison/LALR grammars in C, and I desperately wanted to learn some Rust.
Most of the GraphQL tooling, I'm sorry to say, appears to be in JavaScript. While that's cool, I really believe that when it comes to creating a tool ecosystem, base implementations ought to be in a language that can be consumed by other projects. In other words, the world doesn't need different GraphQL IDL parsers in Node, and Ruby, and Python, and Java, and Scala. The base format should be in something like C/C++/Rust, and then those higher level languages ought to make use of that one foundational library. This ensures consistency and correctness, no matter what your backend is written in.

Usage

Add this to your Cargo.toml:

[dependencies]
graphql-idl-parser = "^0.1"

and this to your crate root:

extern crate graphql_idl_parser;

After that, simply feed in a GraphQL IDL string to gqlidl::parse_schema, like:

let definitions = gqlidl::parse_schema(contents.as_str()).unwrap();
for def in definitions {
  // ...
}

Note that this library does not validate the format if your IDL. If you have multiple types with the same name, for example, they will be happily consumed as unique types. However, the parser will become irate if it comes across a malformed or unknown token.

Todo:

More documentation?
Support more of the IDL besides just types

Use of undeclared type or module

Hello. New user to Rust, GraphQL, all of this basically. Wrote a quick script using some code you suggested and some code from the comments here. The code is as follows...

extern crate graphql_idl_parser;
use std::fs::File;
use std::io::prelude::*;

fn main() {

    let mut file = File::open("schema.idl").expect("Unable to open file");
    let mut contents = String::new();
    file.read_to_string(&mut contents);

    let definitions = gqlidl::parse_schema(contents.as_str()).unwrap();

    for def in definitions {
        match def {
            TypeDefinition::ScalarType(scalar) => {
                println!("{}", scalar.name);
            }
        }
    }
}

When attempting to run this I am seeing errors as follows:

C:\Users\jcocozzi\.cargo\bin\idl_parser\src>cargo build
   Compiling idl_parser v0.1.0 (file:///C:/Users/jcocozzi/.cargo/bin/idl_parser)
error[E0433]: failed to resolve. Use of undeclared type or module `gqlidl`
  --> src\main.rs:11:23
   |
11 |     let definitions = gqlidl::parse_schema(contents.as_str()).unwrap();
   |                       ^^^^^^ Use of undeclared type or module `gqlidl`

error[E0433]: failed to resolve. Use of undeclared type or module `TypeDefinition`
  --> src\main.rs:15:13
   |
15 |             TypeDefinition::ScalarType(scalar) => {
   |             ^^^^^^^^^^^^^^ Use of undeclared type or module `TypeDefinition`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0433`.
error: Could not compile `idl_parser`.

To learn more, run the command again with --verbose.

C:\Users\jcocozzi\.cargo\bin\idl_parser\src>

It would seem as it is not able to find any of these objects. Any suggestions?

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