belongs_to_key

📍 Method

belongs_to_key<T: Entity>(&self) -> T::ID

Extracts the foreign key value from the entity that references its parent entity. This method is used in conjunction with the #[belongs_to] attribute to identify which field in the entity struct serves as the foreign key linking it to its parent entity. The method returns the value of this foreign key, which is typically the unique identifier of the parent entity. This allows you to easily access the parent entity’s ID when working with child entities that belong to it.

🧩 Detailed Example:

use repox::Entity;

#[derive(Debug, Clone, PartialEq, Entity)]
pub struct Widget {
    pub id: u32,
    pub name: String,
}

#[derive(Debug, Clone, PartialEq, Entity)]
#[belongs_to(Widget, widget_id)]
pub struct WidgetProvision {
    pub id: u128,
    pub widget_id: u32,
    pub float: f64,
}

let provision = WidgetProvision { id: 2, widget_id: 42, float: 1.337 };

assert_eq!(provision.belongs_to_key::<Widget>(), 42);