Using an Enum as a Key

The easiest way to expose an enum is to derive num_traits::FromPrimitive and num_traits::ToPrimitive using num-derive, and add an impl EnumKey line:


#[derive(
    Serialize, Deserialize, Debug, num_derive::FromPrimitive, num_derive::ToPrimitive, Clone,
)]
pub enum Category {
    Rust,
    Cooking,
}

impl EnumKey for Category {}

The View code remains unchanged, although the associated Key type can now be set to Option<Category>. The queries can now use the enum instead of a String:


    let rust_post_count = db
        .view::<BlogPostsByCategory>()
        .with_key(Some(Category::Rust))
        .reduce()?;

BonsaiDb will convert the enum to a u64 and use that value as the Key. A u64 was chosen to ensure fairly wide compatibility even with some extreme usages of bitmasks. If you wish to customize this behavior, you can implement Key directly.