Request: Implement a `rename_all = ...` attribute for types

[phrohdoh]

💡 Feature description

Similar to serde's rename_all attribute, this would reformat all of the type's fields / variants for de/serialization to the format specified.

Individual field / variant rename must take precedence over rename_all.

Valid format values should be, at minimum:

• snake_case
• kebab-case
• camelCase
• PascalCase
• SCREAMING_SNAKE_CASE
• SCREAMING-KEBAB-CASE
• UPPERCASE
• lowercase

This rename_all attribute should probably be applicable to types and enum variants.

💻 Basic example

#[derive(Item, PartialEq, Debug, Clone)]
#[dynomite(rename_all = "kebab-case")]
struct Recipe {
    #[dynomite(partition_key]
    #[dynomite(rename = "recipe_id")]
    id: String,
    net_carbs: u64,
}

Should be serialized (to JSON just as an example) as:

{
    "recipe_id": "...",
    "net-carbs": 0
}

references / prior work

• serde's parsing of rename_all

[phrohdoh]

We should consider adding heck, an opinionated & non-customizable case-conversion 3rd-party library crate, as a dependency to the dynomite-derive crate to reduce rework and (potentially) simplify implementation (and testing!) of this feature (since it reformats the existing name, instead of providing a new name entirely).

[phrohdoh]

I've written code that makes the following test pass (using the heck crate, just an implementation detail though). If there is any interest (not seeing any so far on the ticket; no thumbs-up etc), I could continue working on the implementation I currently have. Of course I prefer to not unnecessarily bloat dynomite.

rename_all type-level dynomite attr

#[test]
#[allow(non_snake_case /* specifically testing mixed-case fields */)]
fn derive_item_rename_all_attr_kebab_case() {
    // GIVEN
    #[derive(Item)]
    #[dynomite(rename_all = "kebab-case")]
    struct MyItem {
        #[dynomite(partition_key)]
        _pk: String,
        #[dynomite(sort_key)]
        sk: String,
        #[dynomite(rename = "fooBar")]
        with_Field_levelRename: Option<i32>,

        snake_case: bool,
        camelCase: bool,
        PascalCase: bool,
        SCREAMING_SNAKE_CASE: bool,
        UPPERCASE: bool,
        lowercase: bool,
    }

    let original = MyItem {
        _pk: "6956abd4-665f-433a-b9ad-c038f9c64601".into(),
        sk: "2021-01-20T22:41:41.603Z".into(),
        with_Field_levelRename: Some(1024),
        snake_case: true,
        camelCase: true,
        PascalCase: true,
        SCREAMING_SNAKE_CASE: true,
        UPPERCASE: true,
        lowercase: true,
    };

    // WHEN
    let attrs: Attributes = original.into();

    // THEN
    assert_eq!(attrs.len(), 9);
    assert!(attrs.contains_key("_pk"), "leading underscore retained");
    assert!(attrs.contains_key("sk"), "unchanged");
    assert!(attrs.contains_key("fooBar"), "field-level rename has precedent");
    assert!(attrs.contains_key("snake-case"));
    assert!(attrs.contains_key("camel-case"));
    assert!(attrs.contains_key("pascal-case"));
    assert!(attrs.contains_key("screaming-snake-case"));
    assert!(attrs.contains_key("uppercase"));
    assert!(attrs.contains_key("lowercase"));
}