apollo-parser

A parser for the GraphQL language.

Crates.io version Download docs.rs docs

Features

Getting started

Add this to your Cargo.toml to start using apollo-parser: ```toml

Just an example, change to the necessary package version.

[dependencies] apollo-parser = "0.2.4" ```

Or using [cargo-edit]: bash cargo add apollo-parser

Usage

apollo-parser is built to parse both GraphQL schemas and queries according to the latest [October 2021 specification]. It produces a typed syntax tree that then can be walked, extracting all the necessary information. You can quick start with:

```rust use apollo_parser::Parser;

let input = "union SearchResult = Photo | Person | Cat | Dog"; let parser = Parser::new(input); let ast = parser.parse(); ```

apollo-parser is built to be error-resilient. This means we don't abort parsing (or lexing) if an error occurs. That means parser.parse() will always produce an AST, and it will be accompanied by any errors that are encountered:

```rust use apollo_parser::Parser;

let input = "union SearchResult = Photo | Person | Cat | Dog"; let parser = Parser::new(input); let ast = parser.parse();

// ast.errors() returns an iterator with the errors encountered during lexing and parsing assert_eq!(0, ast.errors().len());

// ast.document() gets the Document, or root node, of the tree that you can // start iterating on. let doc = ast.document(); ```

Examples

Two examples outlined here: * [Get field names in an object] * [Get variables used in a query]

The [examples directory] in this repository has a few more useful implementations such as: * [using apollo-rs with miette to display error diagnostics] * [using apollo-rs with annotate_snippets to display error diagnostics] * [checking for unused variables]

Get field names in an object

```rust use apollo_parser::{ast, Parser};

let input = " type ProductDimension { size: String weight: Float @tag(name: \"hi from inventory value type field\") } "; let parser = Parser::new(input); let ast = parser.parse(); assert_eq!(0, ast.errors().len());

let doc = ast.document();

for def in doc.definitions() { if let ast::Definition::ObjectTypeDefinition(objecttype) = def { asserteq!(objecttype.name().unwrap().text(), "ProductDimension"); for fielddef in objecttype.fieldsdefinition().unwrap().fielddefinitions() { println!("{}", fielddef.name().unwrap().text()); // size weight } } } ```

Get variables used in a query

```rust use apollo_parser::{ast, Parser};

let input = " query GraphQuery($graphid: ID!, $variant: String) { service(id: $graphid) { schema(tag: $variant) { document } } } ";

let parser = Parser::new(input); let ast = parser.parse(); assert_eq!(0, ast.errors().len());

let doc = ast.document();

for def in doc.definitions() { if let ast::Definition::OperationDefinition(opdef) = def { asserteq!(op_def.name().unwrap().text(), "GraphQuery");

      let variable_defs = op_def.variable_definitions();
      let variables: Vec<String> = variable_defs
          .iter()
          .map(|v| v.variable_definitions())
          .flatten()
          .filter_map(|v| Some(v.variable()?.text().to_string()))
          .collect();
      assert_eq!(
          variables.as_slice(),
          ["graph_id".to_string(), "variant".to_string()]
      );
  }

} ```

License

Licensed under either of

at your option.