fix refreshing canteens when menu is empty

scraper/src/refresh.rs

@@ -119,7 +119,9 @@ pub async fn check_refresh(db: &sqlx::PgPool, date: NaiveDate, canteens: &[Cante
                     .difference(&db_dishes)
                     .collect::<HashSet<_>>();
 
-                if let Err(err) = update_stale_dishes(db, date, &stale_dishes, &new_dishes).await {
+                if let Err(err) =
+                    update_stale_dishes(db, date, &stale_dishes, &new_dishes, canteens).await
+                {
                     tracing::error!("Error updating stale dishes in db: {}", err);
                     false
                 } else {
@@ -151,9 +153,11 @@ async fn update_stale_dishes(
     date: NaiveDate,
     stale_dishes: &HashSet<&(Canteen, Dish)>,
     new_dishes: &HashSet<&(Canteen, Dish)>,
+    canteens: &[Canteen],
 ) -> Result<(), sqlx::Error> {
     let mut tx = db.begin().await?;
 
+    if !stale_dishes.is_empty() {
         QueryBuilder::new("UPDATE meals SET is_latest = FALSE WHERE date = ")
             .push_bind(date)
             .push(r#" AND ("name", canteen) IN "#)
@@ -165,18 +169,27 @@ async fn update_stale_dishes(
             .build()
             .execute(&mut *tx)
             .await?;
+    }
 
     let chunks = new_dishes
         .iter()
         .sorted_by_key(|(c, _)| c)
         .chunk_by(|(c, _)| c);
 
-    let new_dishes_iter = chunks.into_iter().map(|(canteen, g)| {
+    let new_dishes_iter = chunks
+        .into_iter()
+        .map(|(canteen, g)| {
             (
                 *canteen,
                 g.map(|(_, dish)| dish).cloned().collect::<Vec<_>>(),
             )
-    });
+        })
+        .chain(
+            canteens
+                .iter()
+                .map(|canteen| (*canteen, Vec::new()))
+                .unique_by(|(c, _)| *c),
+        );
 
     for (canteen, menu) in new_dishes_iter {
         add_menu_to_db(&mut tx, &date, canteen, menu).await?;

scraper/src/util.rs

@@ -85,10 +85,7 @@ pub async fn add_menu_to_db(
     canteen: Canteen,
     menu: Vec<Dish>,
 ) -> Result<(), sqlx::Error> {
-    if menu.is_empty() {
-        return Ok(());
-    }
-
+    if !menu.is_empty() {
         let mut query = sqlx::QueryBuilder::new("INSERT INTO meals (date,canteen,name,dish_type,image_src,price_students,price_employees,price_guests,vegan,vegetarian,kjoules,proteins,carbohydrates,fats) ");
 
         query
@@ -113,6 +110,7 @@ pub async fn add_menu_to_db(
             .build()
             .execute(&mut **db)
             .await?;
+    }
 
     sqlx::query!(
         "INSERT INTO canteens_scraped (scraped_for, canteen) VALUES ($1, $2)",