cleanup

backend/src/utils/named_entity.rs

@@ -0,0 +1,28 @@
+use diesel::QueryResult;
+
+use crate::error::{AppError, AppResult};
+
+/// Trim and validate a user-supplied entity name, returning an owned String.
+///
+/// The `on_empty` closure is only invoked when the trimmed name is empty, giving
+/// callers control over the concrete error that should be surfaced.
+pub fn normalize_name(raw: &str, on_empty: impl Fn() -> AppError) -> AppResult<String> {
+    let trimmed = raw.trim();
+    if trimmed.is_empty() {
+        return Err(on_empty());
+    }
+    Ok(trimmed.to_string())
+}
+
+/// Ensure that no conflicting entity exists by executing the provided query
+/// closure. If a record is returned, the `on_duplicate` closure is evaluated to
+/// produce the appropriate error.
+pub fn ensure_name_available<T>(
+    query: impl FnOnce() -> QueryResult<Option<T>>,
+    on_duplicate: impl Fn() -> AppError,
+) -> AppResult<()> {
+    if query()?.is_some() {
+        return Err(on_duplicate());
+    }
+    Ok(())
+}