tktax-serde 0.2.2

## Overview

This crate provides custom Serde utilities focused on parsing check or serial numbers into an optional `u64`. An empty string is interpreted as `None`, while numeric strings and integral values are parsed as `Some(u64)`.  

## Features

- **Optional Parsing**: Attempts to parse an incoming field as a `u64`, returning `None` if the field is empty.  
- **Robust Error Handling**: Produces structured Serde errors for malformed input, ensuring safe deserialization in production.  

## Usage

Add the following to your `Cargo.toml`:
```toml
[dependencies]
tktax-serde = "0.1.0"
serde = "1.0"
serde_json = "1.0"
```

Import and apply the custom deserializer:

```rust
use serde::Deserialize;
use tktax_serde::parse_check_or_serial_number_opt;

#[derive(Debug, Deserialize)]
struct MyStruct {
    // This field will be deserialized via our custom parser
    #[serde(deserialize_with = "parse_check_or_serial_number_opt")]
    check_number: Option<u64>,
}
```

### Example

```rust
fn main() -> Result<(), serde_json::Error> {
    let json_data_empty = r#"{"check_number": ""}"#;
    let parsed_empty: MyStruct = serde_json::from_str(json_data_empty)?;
    assert_eq!(parsed_empty.check_number, None);

    let json_data_numeric = r#"{"check_number": "42"}"#;
    let parsed_numeric: MyStruct = serde_json::from_str(json_data_numeric)?;
    assert_eq!(parsed_numeric.check_number, Some(42));

    let json_data_int = r#"{"check_number": 123}"#;
    let parsed_int: MyStruct = serde_json::from_str(json_data_int)?;
    assert_eq!(parsed_int.check_number, Some(123));

    Ok(())
}
```

## Testing

Run tests using:
```bash
cargo test --package tktax-serde
```

The comprehensive test suite verifies empty string handling, numeric string conversion, and numeric literal conversion, ensuring proper adherence to expected deserialization behavior.

## Contributing

1. Fork the repository  
2. Create a feature branch  
3. Commit your changes  
4. Open a pull request  

Issues and pull requests are welcomed to improve functionality, fix bugs, or enhance documentation.

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© 2025 tktax-serde contributors. Licensed under the Apache-2.0 License.