Module diagnostic 

Pretty-printable diagnostic reports for errors that reference GraphQL documents.

Usage

To use pretty-printing in custom errors, implement the ToCliReport trait.

use apollo_compiler::parser::SourceSpan;
use apollo_compiler::Schema;
use apollo_compiler::Name;
use apollo_compiler::diagnostic::CliReport;
use apollo_compiler::diagnostic::Diagnostic;
use apollo_compiler::diagnostic::ToCliReport;

/// Error type for a small GraphQL schema linter.
#[derive(Debug, thiserror::Error)]
enum LintError {
    #[error("{name} should be PascalCase")]
    InvalidCase { name: Name },
    #[error("Missing @specifiedBy directive on scalar {name}")]
    NoSpecifiedBy {
        location: Option<SourceSpan>,
        name: Name,
    },
}

impl ToCliReport for LintError {
    fn location(&self) -> Option<SourceSpan> {
        match self {
            LintError::InvalidCase { name } => name.location(),
            LintError::NoSpecifiedBy { location, .. } => *location,
        }
    }

    fn report(&self, report: &mut CliReport<'_>) {
        match self {
            LintError::InvalidCase { name } => {
                report.with_label_opt(name.location(), "should be PascalCase");
                report.with_help(format!("Try using {}", to_pascal_case(name)));
            }
            LintError::NoSpecifiedBy { location, .. } => {
                report.with_label_opt(*location, "scalar does not have a specification");
            }
        }
    }
}

The Diagnostic type wraps errors that implement ToCliReport and provides the pretty-printing functionality. ToCliReport::to_diagnostic returns a diagnostic ready for formatting:

fn print_errors(schema: &Schema, errors: &[LintError]) {
    for error in errors {
        // Debug-formatting uses colors.
        eprintln!("{:?}", error.to_diagnostic(&schema.sources));
    }
}

Structs

CliReport

A diagnostic report that can be printed to a CLI with pretty colors and labeled lines of GraphQL source code.

Diagnostic

An error bundled together with a source map, for conversion either to a pretty-printable CLI report or to a JSON-serializable GraphQL error.

Enums

Color

Indicate when to use ANSI colors for printing.

Traits

ToCliReport

Conversion to CliReport