diff --git a/juniper/CHANGELOG.md b/juniper/CHANGELOG.md
index 49a1957c6..5d6178a20 100644
--- a/juniper/CHANGELOG.md
+++ b/juniper/CHANGELOG.md
@@ -4,6 +4,14 @@
- Support raw identifiers in field and argument names. (#[object] macro)
+- Most error types now implement `std::error::Error`:
+ - `GraphQLError`
+ - `LexerError`
+ - `ParseError`
+ - `RuleError`
+
+See [#419](https://github.com/graphql-rust/juniper/pull/419).
+
## Breaking Changes
- remove old `graphql_object!` macro, rename `object` proc macro to `graphql_object`
diff --git a/juniper/src/executor/mod.rs b/juniper/src/executor/mod.rs
index 093bb6601..c5209a7f2 100644
--- a/juniper/src/executor/mod.rs
+++ b/juniper/src/executor/mod.rs
@@ -1,4 +1,10 @@
-use std::{borrow::Cow, cmp::Ordering, collections::HashMap, fmt::Display, sync::RwLock};
+use std::{
+ borrow::Cow,
+ cmp::Ordering,
+ collections::HashMap,
+ fmt::{self, Debug, Display},
+ sync::RwLock,
+};
use fnv::FnvHashMap;
diff --git a/juniper/src/lib.rs b/juniper/src/lib.rs
index e0c858664..5a1b9d433 100644
--- a/juniper/src/lib.rs
+++ b/juniper/src/lib.rs
@@ -157,6 +157,7 @@ use crate::{
parser::{parse_document_source, ParseError, Spanning},
validation::{validate_input_values, visit_all_rules, ValidatorContext},
};
+use std::fmt;
pub use crate::{
ast::{FromInputValue, InputValue, Selection, ToInputValue, Type},
@@ -193,6 +194,26 @@ pub enum GraphQLError<'a> {
IsSubscription,
}
+impl<'a> fmt::Display for GraphQLError<'a> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ match self {
+ GraphQLError::ParseError(error) => write!(f, "{}", error),
+ GraphQLError::ValidationError(errors) => {
+ for error in errors {
+ writeln!(f, "{}", error)?;
+ }
+ Ok(())
+ }
+ GraphQLError::NoOperationProvided => write!(f, "No operation provided"),
+ GraphQLError::MultipleOperationsProvided => write!(f, "Multiple operations provided"),
+ GraphQLError::UnknownOperationName => write!(f, "Unknown operation name"),
+ GraphQLError::IsSubscription => write!(f, "Subscription are not currently supported"),
+ }
+ }
+}
+
+impl<'a> std::error::Error for GraphQLError<'a> {}
+
/// Execute a query in a provided schema
pub fn execute<'a, S, CtxT, QueryT, MutationT>(
document_source: &'a str,
diff --git a/juniper/src/parser/lexer.rs b/juniper/src/parser/lexer.rs
index 5d8854e9c..4a18afee4 100644
--- a/juniper/src/parser/lexer.rs
+++ b/juniper/src/parser/lexer.rs
@@ -538,3 +538,5 @@ impl fmt::Display for LexerError {
}
}
}
+
+impl std::error::Error for LexerError {}
diff --git a/juniper/src/parser/parser.rs b/juniper/src/parser/parser.rs
index 095fc1e7e..198c24322 100644
--- a/juniper/src/parser/parser.rs
+++ b/juniper/src/parser/parser.rs
@@ -203,3 +203,5 @@ impl<'a> fmt::Display for ParseError<'a> {
}
}
}
+
+impl<'a> std::error::Error for ParseError<'a> {}
diff --git a/juniper/src/parser/utils.rs b/juniper/src/parser/utils.rs
index d5bd2c915..5ea12817c 100644
--- a/juniper/src/parser/utils.rs
+++ b/juniper/src/parser/utils.rs
@@ -90,6 +90,14 @@ impl<T> Spanning<T> {
}
}
+impl<T: fmt::Display> fmt::Display for Spanning<T> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ write!(f, "{}. At {}", self.item, self.start)
+ }
+}
+
+impl<T: std::error::Error> std::error::Error for Spanning<T> {}
+
impl SourcePosition {
#[doc(hidden)]
pub fn new(index: usize, line: usize, col: usize) -> SourcePosition {
@@ -142,3 +150,9 @@ impl SourcePosition {
self.col
}
}
+
+impl fmt::Display for SourcePosition {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ write!(f, "{}:{}", self.line, self.col)
+ }
+}
diff --git a/juniper/src/validation/context.rs b/juniper/src/validation/context.rs
index 9498bbdae..9a02ae15e 100644
--- a/juniper/src/validation/context.rs
+++ b/juniper/src/validation/context.rs
@@ -1,4 +1,7 @@
-use std::{collections::HashSet, fmt::Debug};
+use std::{
+ collections::HashSet,
+ fmt::{self, Debug},
+};
use crate::ast::{Definition, Document, Type};
@@ -48,6 +51,21 @@ impl RuleError {
}
}
+impl fmt::Display for RuleError {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ // this is fine since all `RuleError`s should have at least one source position
+ let locations = self
+ .locations
+ .iter()
+ .map(|location| format!("{}", location))
+ .collect::<Vec<_>>()
+ .join(", ");
+ write!(f, "{}. At {}", self.message, locations)
+ }
+}
+
+impl std::error::Error for RuleError {}
+
impl<'a, S: Debug> ValidatorContext<'a, S> {
#[doc(hidden)]
pub fn new(schema: &'a SchemaType<S>, document: &Document<'a, S>) -> ValidatorContext<'a, S> {
diff --git a/juniper/src/value/mod.rs b/juniper/src/value/mod.rs
index ab7015abe..6e29b069c 100644
--- a/juniper/src/value/mod.rs
+++ b/juniper/src/value/mod.rs
@@ -2,6 +2,7 @@ use crate::{
ast::{InputValue, ToInputValue},
parser::Spanning,
};
+use std::fmt::{self, Display, Formatter};
mod object;
mod scalar;
@@ -185,6 +186,46 @@ impl<S: ScalarValue> ToInputValue<S> for Value<S> {
}
}
+impl<S: ScalarValue> Display for Value<S> {
+ fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+ match self {
+ Value::Null => write!(f, "null"),
+ Value::Scalar(s) => {
+ if let Some(string) = s.as_string() {
+ write!(f, "\"{}\"", string)
+ } else {
+ write!(f, "{}", s)
+ }
+ }
+ Value::List(list) => {
+ write!(f, "[")?;
+ for (idx, item) in list.iter().enumerate() {
+ write!(f, "{}", item)?;
+ if idx < list.len() - 1 {
+ write!(f, ", ")?;
+ }
+ }
+ write!(f, "]")?;
+
+ Ok(())
+ }
+ Value::Object(obj) => {
+ write!(f, "{{")?;
+ for (idx, (key, value)) in obj.iter().enumerate() {
+ write!(f, "\"{}\": {}", key, value)?;
+
+ if idx < obj.field_count() - 1 {
+ write!(f, ", ")?;
+ }
+ }
+ write!(f, "}}")?;
+
+ Ok(())
+ }
+ }
+ }
+}
+
impl<S, T> From<Option<T>> for Value<S>
where
S: ScalarValue,
@@ -354,4 +395,82 @@ mod tests {
)
);
}
+
+ #[test]
+ fn display_null() {
+ let s: Value<DefaultScalarValue> = graphql_value!(None);
+ assert_eq!("null", format!("{}", s));
+ }
+
+ #[test]
+ fn display_int() {
+ let s: Value<DefaultScalarValue> = graphql_value!(123);
+ assert_eq!("123", format!("{}", s));
+ }
+
+ #[test]
+ fn display_float() {
+ let s: Value<DefaultScalarValue> = graphql_value!(123.456);
+ assert_eq!("123.456", format!("{}", s));
+ }
+
+ #[test]
+ fn display_string() {
+ let s: Value<DefaultScalarValue> = graphql_value!("foo");
+ assert_eq!("\"foo\"", format!("{}", s));
+ }
+
+ #[test]
+ fn display_bool() {
+ let s: Value<DefaultScalarValue> = graphql_value!(false);
+ assert_eq!("false", format!("{}", s));
+
+ let s: Value<DefaultScalarValue> = graphql_value!(true);
+ assert_eq!("true", format!("{}", s));
+ }
+
+ #[test]
+ fn display_list() {
+ let s: Value<DefaultScalarValue> = graphql_value!([1, None, "foo"]);
+ assert_eq!("[1, null, \"foo\"]", format!("{}", s));
+ }
+
+ #[test]
+ fn display_list_one_element() {
+ let s: Value<DefaultScalarValue> = graphql_value!([1]);
+ assert_eq!("[1]", format!("{}", s));
+ }
+
+ #[test]
+ fn display_list_empty() {
+ let s: Value<DefaultScalarValue> = graphql_value!([]);
+ assert_eq!("[]", format!("{}", s));
+ }
+
+ #[test]
+ fn display_object() {
+ let s: Value<DefaultScalarValue> = graphql_value!({
+ "int": 1,
+ "null": None,
+ "string": "foo",
+ });
+ assert_eq!(
+ r#"{"int": 1, "null": null, "string": "foo"}"#,
+ format!("{}", s)
+ );
+ }
+
+ #[test]
+ fn display_object_one_field() {
+ let s: Value<DefaultScalarValue> = graphql_value!({
+ "int": 1,
+ });
+ assert_eq!(r#"{"int": 1}"#, format!("{}", s));
+ }
+
+ #[test]
+ fn display_object_empty() {
+ let s = Value::<DefaultScalarValue>::object(Object::with_capacity(0));
+ assert_eq!(r#"{}"#, format!("{}", s));
+ }
}