hydracache_db/entity.rs
1use hydracache::CacheKeyBuilder;
2
3/// Static cache metadata for a domain entity.
4///
5/// Implement this trait manually when you want domain-shaped cache calls without
6/// repeating entity and collection names at every query site. A future derive
7/// macro can generate the same implementation.
8///
9/// # Example
10///
11/// ```rust
12/// use hydracache_db::CacheEntity;
13///
14/// struct User;
15///
16/// impl CacheEntity for User {
17/// type Id = i64;
18///
19/// const ENTITY: &'static str = "user";
20/// const COLLECTION: Option<&'static str> = Some("users");
21/// }
22///
23/// assert_eq!(User::cache_key_for(&42), "user:42");
24/// assert_eq!(User::entity_tag_for(&42), "user:42");
25/// assert_eq!(User::collection_tag(), Some("users".to_owned()));
26/// ```
27pub trait CacheEntity {
28 /// Identifier type used to build entity keys and tags.
29 type Id: ToString;
30
31 /// Stable entity segment used in keys and entity tags.
32 const ENTITY: &'static str;
33
34 /// Optional collection tag for broader invalidation groups.
35 const COLLECTION: Option<&'static str>;
36
37 /// Build the logical cache key for this entity id.
38 fn cache_key_for(id: &Self::Id) -> String {
39 CacheKeyBuilder::new()
40 .entity(Self::ENTITY, id.to_string())
41 .build_string()
42 }
43
44 /// Build the entity invalidation tag for this id.
45 fn entity_tag_for(id: &Self::Id) -> String {
46 Self::cache_key_for(id)
47 }
48
49 /// Build the optional collection invalidation tag.
50 fn collection_tag() -> Option<String> {
51 Self::COLLECTION.map(|collection| CacheKeyBuilder::from_segment(collection).build_string())
52 }
53}