serde-json-diagnostics

A serde_json extension for better deserialization error diagnostics with accurate JSON path tracking.

Overview

This crate provides drop-in replacements for serde_json::from_str, serde_json::from_slice, and serde_json::from_reader that return enhanced errors with JSON path information. The path tracking helps you quickly identify where in your JSON structure a deserialization error occurred.

Current Status: Phase 1 complete - API is functional and ready for use. Path tracking implementation is pending and will be added in a future update.

Installation

Add this to your Cargo.toml:

[dependencies]
serde_json_diagnostics = "0.1.0"

Usage

Replace your serde_json deserialization calls with the equivalents from this crate:

use serde::Deserialize;
use serde_json_diagnostics::from_str;

#[derive(Deserialize)]
struct User {
    name: String,
    age: u32,
}

fn main() -> Result<(), serde_json_diagnostics::ErrorDiagnostic> {
    let json = r#"{"name": "Alice", "age": 30}"#;
    let user: User = from_str(json)?;

    println!("User: {} is {} years old", user.name, user.age);
    Ok(())
}

API Functions

The crate provides three functions with the same signatures as serde_json:

• from_str<'a, T>(s: &'a str) -> Result<T> - Deserialize from a JSON string
• from_slice<'a, T>(bytes: &'a [u8]) -> Result<T> - Deserialize from a byte slice
• from_reader<R, T>(reader: R) -> Result<T> - Deserialize from an IO reader

All functions return Result<T, ErrorDiagnostic> instead of Result<T, serde_json::Error>.

Example: Error Handling

use serde::Deserialize;
use serde_json_diagnostics::from_str;

#[derive(Deserialize)]
struct Config {
    debug: bool,
    port: u16,
}

let json = r#"{"debug": true, "port": "invalid"}"#;
match from_str::<Config>(json) {
    Ok(config) => println!("Loaded config: {:?}", config),
    Err(e) => eprintln!("Failed to parse JSON: {}", e),
}

Features

• Drop-in replacement for serde_json::from_str, from_slice, and from_reader
• Same API signatures as serde_json (only error type changes)
• Enhanced error type (ErrorDiagnostic) that wraps serde_json::Error
• Path tracking (WIP)

Why This Crate?

The standard serde_path_to_error crate has known issues with path tracking for certain enum representations (internally tagged, adjacently tagged, and untagged enums). This crate aims to provide more reliable path tracking using breadcrumb-style navigation, while maintaining the same ergonomic API as serde_json.

Credits to @BrokenStandards.

License

MIT License.

Acknowledgments

• serde - Serialization framework for Rust
• serde_json - JSON support for serde
• serde_path_to_error - Find out path at which a deserialization error occurred