Question about select for update.

[realsama]

Hello there,

I have started using this crate recently and I am curious about how to do a select for update. I have the below code.

connection
        .transaction::<_, Error, _>(|conn| {
            {
                async move {
                    let item = items::table
                        .select(items::all_columns)
                        .for_update()
                        .filter(items::item_id.eq(generic_item_id))
                        .first(conn)
                        .await?;
                   
                    // check and run code that needs row-level locking to prevent a race.

                    let updated_item = diesel::update(items::table)
                        .filter(items::id.eq(item.id))
                        .set(items::generic_field.eq(generic_value))
                        .execute(conn)
                        .await?;

                    Ok(())
                }
            }
            .scope_boxed()
        })
        .await?;

Do you think this code block is guaranteed to achieve what I am trying to do (lock the row until the whole block executes)? Thanks

[weiznich]

for_update translates to a FOR UPDATE locking clause. See the relevant documentation for details:

• Postgres
• Mysql