Struct FieldError

pub struct FieldError<S = DefaultScalarValue> { /* private fields */ }

Error type for errors that occur during field resolution

Field errors are represented by a human-readable error message and an optional Value structure containing additional information.

They can be converted to from any type that implements std::fmt::Display, which makes error chaining with the ? operator a breeze:

fn get_string(data: Vec<u8>) -> Result<String, FieldError>
{
    let s = String::from_utf8(data)?;
    Ok(s)
}

Implementations

impl<S> FieldError<S>

pub fn new<T: Display>(e: T, extensions: Value<S>) -> Self

Construct a new FieldError with additional data.

You can use the graphql_value! macro for construction:

use juniper::{graphql_value, FieldError};

FieldError::new(
    "Could not open connection to the database",
    graphql_value!({"internal_error": "Connection refused"}),
);

The extensions parameter will be added to the "extensions" field of the "errors" object in response:

{
  "errors": [
    "message": "Could not open connection to the database",
    "locations": [{"line": 2, "column": 4}],
    "extensions": {
      "internal_error": "Connection refused"
    }
  ]
}

If the argument is Value::Null, then no extra data will be included.

pub fn message(&self) -> &str

Returns "message" field of this FieldError.

pub fn extensions(&self) -> &Value<S>

Returns "extensions" field of this FieldError.

If there is no "extensions", then Value::Null will be returned.

pub fn map_scalar_value<Into>(self) -> FieldError<Into>

where S: ScalarValue, Into: ScalarValue,

Maps the ScalarValue type of this FieldError into the specified one.

pub fn map_message(self, f: impl FnOnce(String) -> String) -> Self

Maps the FieldError::message with the given function.

Trait Implementations

impl<S: Clone> Clone for FieldError<S>

fn clone(&self) -> FieldError<S>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<S: Debug> Debug for FieldError<S>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Display, S> From<T> for FieldError<S>

fn from(e: T) -> Self

Converts to this type from the input type.

impl<S1: ScalarValue, S2: ScalarValue> IntoFieldError<S2> for FieldError<S1>

fn into_field_error(self) -> FieldError<S2>

Performs the custom conversion into a FieldError.

impl<S: PartialEq> PartialEq for FieldError<S>

fn eq(&self, other: &FieldError<S>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<S> StructuralPartialEq for FieldError<S>