upload picture now working well

src/controllers/admin_products.rs

@@ -526,7 +526,7 @@ async fn update(
 
     if let Some(data) = form.image {
         let filename = store_image(&ctx, data).await?;
-        let next_position = product_images::count_for(&ctx, id).await?;
+        let next_position = product_images::count_for(&txn, id).await?;
         product_images::ActiveModel {
             product_id: Set(id),
             image_id: Set(filename),

src/models/product_images.rs

@@ -38,10 +38,14 @@ pub async fn first_for(ctx: &AppContext, product_id: i32) -> Result<Option<Strin
 }
 
 /// Number of images already attached to a product, used to position new uploads.
-pub async fn count_for(ctx: &AppContext, product_id: i32) -> Result<i32> {
+///
+/// Takes a connection rather than the `AppContext` so it can run on an open
+/// transaction; calling it on `ctx.db` while a transaction holds the pool's only
+/// connection would deadlock the pool.
+pub async fn count_for<C: ConnectionTrait>(db: &C, product_id: i32) -> Result<i32> {
     use sea_orm::PaginatorTrait;
     Ok(Entity::find()
         .filter(Column::ProductId.eq(product_id))
-        .count(&ctx.db)
+        .count(db)
         .await? as i32)
 }