Derive Macro SelectChoice 

#[derive(SelectChoice)]
{
    // Attributes available to this derive:
    #[select_choice]
}

Derive the SelectChoice trait for an enum.

This macro automatically implements the SelectChoice trait for enums, allowing them to be used with SelectField and SelectMultipleField form fields. The macro generates implementations for all required methods based on the enum variants.

Requirements

• The type must be an enum (not a struct or union)
• The enum must have at least one variant
• All variants must be unit variants (no associated data)

Default Behavior

By default, the macro uses the variant name for both the ID and display name:

• id() returns the variant name as a string
• to_string() returns the variant name as a string
• from_str() matches the variant name (case-sensitive)
• default_choices() returns all variants in declaration order

Attributes

You can customize the behavior using the #[select_choice(...)] attribute on individual enum variants:

id

Override the ID used for this variant in form submissions and HTML.

use cot::form::fields::SelectChoice;

#[derive(SelectChoice, Debug, PartialEq)]
enum Status {
    #[select_choice(id = "draft")]
    Draft,
    #[select_choice(id = "published")]
    Published,
}

assert_eq!(Status::Draft.id(), "draft");
assert_eq!(Status::Published.id(), "published");

name

Override the display name shown to users in the select dropdown.

use cot::form::fields::SelectChoice;

#[derive(SelectChoice, Debug, PartialEq)]
enum Priority {
    #[select_choice(name = "Low Priority")]
    Low,
    #[select_choice(name = "High Priority")]
    High,
}

assert_eq!(Priority::Low.to_string(), "Low Priority");
assert_eq!(Priority::High.to_string(), "High Priority");

Error Cases

The macro will fail to compile if:

• The type is not an enum
• The enum has no variants
• Any variant has associated data (non-unit variants)

use cot_macros::SelectChoice;

// This will fail - structs are not supported
#[derive(SelectChoice)]
struct NotAnEnum {
    field: String,
}

use cot_macros::SelectChoice;

// This will fail - empty enums are not supported
#[derive(SelectChoice)]
enum EmptyEnum {}

use cot_macros::SelectChoice;

// This will fail - only unit variants are supported
#[derive(SelectChoice)]
enum EnumWithData {
    Unit,
    WithData(String),
    WithFields { field: i32 },
}