[Rust] Capability based DbContext

crates/bindings/src/lib.rs

@@ -912,6 +912,8 @@ pub use spacetimedb_bindings_macro::view;
 pub struct QueryBuilder {}
 pub use query_builder::{Query, RawQuery};
 
+use crate::http::{HandlerContext, HttpClient};
+
 /// One of two possible types that can be passed as the first argument to a `#[view]`.
 /// The other is [`ViewContext`].
 /// Use this type if the view does not depend on the caller's identity.
@@ -1440,6 +1442,7 @@ impl ProcedureContext {
 }
 
 /// A handle on a database with a particular table schema.
+#[deprecated(note = "Use the capability based traits (CtxDbRead, CtxDbWrite) instead!")]
 pub trait DbContext {
     /// A view into the tables of a database.
     ///
@@ -1461,6 +1464,7 @@ pub trait DbContext {
     fn db_read_only(&self) -> &LocalReadOnly;
 }
 
+#[allow(deprecated)]
 impl DbContext for AnonymousViewContext {
     type DbView = LocalReadOnly;
 
@@ -1473,6 +1477,7 @@ impl DbContext for AnonymousViewContext {
     }
 }
 
+#[allow(deprecated)]
 impl DbContext for ReducerContext {
     type DbView = Local;
 
@@ -1485,6 +1490,7 @@ impl DbContext for ReducerContext {
     }
 }
 
+#[allow(deprecated)]
 impl DbContext for TxContext {
     type DbView = Local;
 
@@ -1497,6 +1503,7 @@ impl DbContext for TxContext {
     }
 }
 
+#[allow(deprecated)]
 impl DbContext for ViewContext {
     type DbView = LocalReadOnly;
 
@@ -1526,6 +1533,111 @@ impl Local {
     }
 }
 
+/// This trait allows you to be generic over all contexts that allow you to read from the db.
+/// including views, reducers and even procedures and http handlers through [TxContext].
+/// Useful when trying to encapsulate logic in reusable parts.
+pub trait CtxDbRead {
+    fn db_read_only(&self) -> &LocalReadOnly;
+}
+
+impl CtxDbRead for TxContext {
+    fn db_read_only(&self) -> &LocalReadOnly {
+        &LocalReadOnly {}
+    }
+}
+
+impl CtxDbRead for ReducerContext {
+    fn db_read_only(&self) -> &LocalReadOnly {
+        &LocalReadOnly {}
+    }
+}
+
+impl CtxDbRead for ViewContext {
+    fn db_read_only(&self) -> &LocalReadOnly {
+        &LocalReadOnly {}
+    }
+}
+
+impl CtxDbRead for AnonymousViewContext {
+    fn db_read_only(&self) -> &LocalReadOnly {
+        &LocalReadOnly {}
+    }
+}
+
+/// This trait allows you to be generic over all contexts that allow read/write access to the db.
+pub trait CtxDbWrite: CtxDbRead {
+    fn db(&self) -> &Local;
+}
+
+impl CtxDbWrite for TxContext {
+    fn db(&self) -> &Local {
+        &Local {}
+    }
+}
+
+impl CtxDbWrite for ReducerContext {
+    fn db(&self) -> &Local {
+        &Local {}
+    }
+}
+
+/// This trait allows you to be generic over all contexts that allow to retrieve the caller [Identity].
+pub trait CtxWithSender {
+    fn sender(&self) -> Identity;
+}
+
+impl CtxWithSender for ViewContext {
+    fn sender(&self) -> Identity {
+        self.sender
+    }
+}
+
+impl CtxWithSender for ReducerContext {
+    fn sender(&self) -> Identity {
+        self.sender
+    }
+}
+
+impl CtxWithSender for TxContext {
+    fn sender(&self) -> Identity {
+        self.0.sender
+    }
+}
+
+/// This trait allows you to be generic over all contexts that allow to retrieve the [Timestamp] of calling them.
+pub trait CtxWithTimestamp {
+    fn timestamp(&self) -> Timestamp;
+}
+
+impl CtxWithTimestamp for ReducerContext {
+    fn timestamp(&self) -> Timestamp {
+        self.timestamp
+    }
+}
+
+impl CtxWithTimestamp for TxContext {
+    fn timestamp(&self) -> Timestamp {
+        self.timestamp
+    }
+}
+
+/// This trait allows you to be generic over all contexts that allow to use the [HttpClient].
+pub trait CtxWithHttp {
+    fn http(&self) -> &HttpClient;
+}
+
+impl CtxWithHttp for HandlerContext {
+    fn http(&self) -> &HttpClient {
+        &self.http
+    }
+}
+
+impl CtxWithHttp for ProcedureContext {
+    fn http(&self) -> &HttpClient {
+        &self.http
+    }
+}
+
 /// The [JWT] of an [`AuthCtx`].
 ///
 /// [JWT]: https://en.wikipedia.org/wiki/JSON_Web_Token