impl Error

fn line(&self) -> usize

One-based line number at which the error was detected.

Characters in the first line of the input (before the first newline character) are in line 1.

fn column(&self) -> usize

One-based column number at which the error was detected.

The first character in the input and any characters immediately following a newline character are in column 1.

Note that errors may occur in column 0, for example if a read from an I/O stream fails immediately following a previously read newline character.

fn classify(&self) -> Category

Categorizes the cause of this error.

• Category::Io - failure to read or write bytes on an I/O stream
• Category::Syntax - input that is not syntactically valid JSON
• Category::Data - input data that is semantically incorrect
• Category::Eof - unexpected end of the input data

fn is_io(&self) -> bool

Returns true if this error was caused by a failure to read or write bytes on an I/O stream.

fn is_syntax(&self) -> bool

Returns true if this error was caused by input that was not syntactically valid JSON.

fn is_data(&self) -> bool

Returns true if this error was caused by input data that was semantically incorrect.

For example, JSON containing a number is semantically incorrect when the type being deserialized into holds a String.

fn is_eof(&self) -> bool

Returns true if this error was caused by prematurely reaching the end of the input data.

Callers that process streaming input may be interested in retrying the deserialization once more data is available.

fn io_error_kind(&self) -> Option<ErrorKind>

The kind reported by the underlying standard library I/O error, if this error was caused by a failure to read or write bytes on an I/O stream.

Example

use serde_json::Value;
use std::io::{self, ErrorKind, Read};
use std::process;

struct ReaderThatWillTimeOut<'a>(&'a [u8]);

impl<'a> Read for ReaderThatWillTimeOut<'a> {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        if self.0.is_empty() {
            Err(io::Error::new(ErrorKind::TimedOut, "timed out"))
        } else {
            self.0.read(buf)
        }
    }
}

fn main() {
    let reader = ReaderThatWillTimeOut(br#" {"k": "#);

    let _: Value = match serde_json::from_reader(reader) {
        Ok(value) => value,
        Err(error) => {
            if error.io_error_kind() == Some(ErrorKind::TimedOut) {
                // Maybe this application needs to retry certain kinds of errors.

                # return;
            } else {
                eprintln!("error: {}", error);
                process::exit(1);
            }
        }
    };
}