https://github.com/zakarumych/serde-nothing

Serialize to nothing. Deserialize from nothing
https://github.com/zakarumych/serde-nothing

Last synced: about 2 months ago
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Serialize to nothing. Deserialize from nothing

• Host: GitHub
• URL: https://github.com/zakarumych/serde-nothing
• Owner: zakarumych
• License: other
• Created: 2022-02-25T15:26:48.000Z (over 3 years ago)
• Default Branch: master
• Last Pushed: 2022-02-25T16:21:46.000Z (over 3 years ago)
• Last Synced: 2024-10-31T11:54:46.612Z (8 months ago)
• Language: Rust
• Size: 10.7 KB
• Stars: 7
• Watchers: 1
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: COPYING

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README

        
# serde-nothing

[![crates](https://img.shields.io/crates/v/serde-nothing.svg?style=for-the-badge&label=serde-nothing)](https://crates.io/crates/serde-nothing)

[![docs](https://img.shields.io/badge/docs.rs-serde--nothing-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white)](https://docs.rs/serde-nothing)

[![actions](https://img.shields.io/github/workflow/status/zakarumych/serde-nothing/badge/master?style=for-the-badge)](https://github.com/zakarumych/serde-nothing/actions?query=workflow%3ARust)

[![MIT/Apache](https://img.shields.io/badge/license-MIT%2FApache-blue.svg?style=for-the-badge)](COPYING)

![loc](https://img.shields.io/tokei/lines/github/zakarumych/serde-nothing?style=for-the-badge)

This crate defines "nothing" in terms of `serde` data model

and allows checking values and create such values using only `Serialize` and `Deserialize` traits.

# Motivation

This crate is designed to generalize serialization pattern

where struct fields with None/empty/default values are skipped on serialization

and constructed on deserialization when missing.

Usually this pattern is coded using `#[serde(default, skip_serializing_if = "Option::is_none/Vec::is_empty/is_default")]`.

Where `is_default` is a function defined as

```rust

fn is_default(value: &T) -> bool {

    *value == T::default()

}

```

The pattern works very well for field with concrete types and generic wrappers like `Option`, `Vec` and similar.

But using `#[serde(default)]` on field with generic type `T` would require `Default` bound added to the `Deserialize` impl.

And `#[serde(skip_serializing_if = "is_default")]` would require `T: Default + PartialEq` bound added to the `Serialize` impl.

This crate allows to implement this pattern without additional bounds.

Even more, it allows specialize for types that can be skipped.

That is, if field has type `T` that does not even have a value that would be appropriate to skip,

the code will continue work correctly and would simply always serialize the field and require the data for deserialization.

# Magic? No, science!

This crate provides stateless `Nothing` type which is a special kind of `serde::Serializer` or `serde::Deserializer`.

`Nothing` can be used to serialize and deserialize "nothing" values.

"Nothing" values are `None`, empty collections, units,

structs and tuples where all fields are "nothing"

Serializing a "non-nothing" value with `Nothing` always fails.

As deserializer `Nothing` would visit most appropriate `Visitor` method

with matching kind of nothingness, like `None`, empty slice/sequence/map,

single-variant enum with nothing in discriminant and nothing in payload,

`0` numeric value etc.

User would most probably want to use a shortcut and utilize `is_nothing` function for serialization

and `from_nothing` function for deserialization.

## License

Licensed under either of

* Apache License, Version 2.0, ([license/APACHE](license/APACHE) or http://www.apache.org/licenses/LICENSE-2.0)

* MIT license ([license/MIT](license/MIT) or http://opensource.org/licenses/MIT)

at your option.

## Contributions

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.