more multi-tenancy

backend/src/utils/validation.rs

@@ -0,0 +1,10 @@
+use crate::error::{AppError, AppResult};
+
+/// Ensure an entity exists, returning a bad request error when it does not.
+pub fn ensure_exists(exists: bool, entity: &str) -> AppResult<()> {
+    if exists {
+        Ok(())
+    } else {
+        Err(AppError::bad_request(format!("{entity} does not exist")))
+    }
+}