No field `storeId` on type `&mut std::option::Option<BusinessInfo<T>>`

Question

I need to add an item in storage but when I build the project, I get this error:

error[E0609]: no field storeId on type &mut std::option::Option<BusinessInfo<T>> --> pallets/bussines/src/lib.rs:171:25 | 171 | ensure!((Some(store.storeId) == Some(store_id)), <Error>::StoreItemNotFound);

I don't know what the problem is.

this is BusinessInfo struct:

#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
#[scale_info(skip_type_params(T))]
#[codec(mel_bound())]
pub struct BusinessInfo<T: Config> {
    logo: Vec<u8>,
    storeId: [u8; 16],
    owner: <T as frame_system::Config>::AccountId,
    description: Vec<u8>,
    name: Vec<u8>,
}

I tried to check if business exists add item if not show error:

    #[pallet::weight(10000)]
    #[transactional]
    pub fn add_item(
        origin: OriginFor<T>,
        store_id: [u8; 16],
        media: Vec<u8>,
        title: Vec<u8>,
        description: Vec<u8>,
        price: u32,
        count: u32,
    ) -> DispatchResult {
        let who = ensure_signed(origin)?;

        let item_id = Self::gen_dna();

        let item_info = BusinessItem {
            media: media.clone(),
            title: title.clone(),
            description: description.clone(),
            price: price.clone(),
            count: count.clone(),
            itemId: item_id,
        };

        Business::<T>::mutate(who.clone(), |store| -> DispatchResult {
            ensure!((Some(store.storeId) == Some(store_id)), <Error<T>>::StoreItemNotFound);
            let mut store_item_vec: Vec<BusinessItem> = Vec::new();
            store_item_vec.push(item_info);
            <Items<T>>::insert(item_id, who.clone(), store_item_vec);
            Ok(())
        });

        Self::deposit_event(Event::ItemCreated(Some(item_id)));

        Ok(())
    }

and this is Business Storage:

    #[pallet::storage]
#[pallet::getter(fn business)]
pub(super) type Business<T: Config> =
    StorageMap<_, Twox64Concat, T::AccountId, BusinessInfo<T>>;

Answer 1

Each storage item has a QueryKind set at declaration. This QueryKind defines the behavior/return value of functions like get and also mutate. There are currently three different query kinds defined in Substrate:

• ValueQuery: Returns Default::default() if the value doesn't exist in the state or the value from the state.
• OptionQuery Returns None if the value doesn't exist in the state or the value from the state wrapped in Some(_).
• ResultQuery Returns Err(_) if the value doesn't exist in the state or the value from the state wrapped in Ok(_).

The default QueryKind is OptionQuery. In your example this would mean that your closure that you pass to mutate gets passed a &mut Option<BusinessInfo<T>>. So, writing:

Business::<T>::mutate(who.clone(), |store| -> DispatchResult {
    if let Some(store) = &mut store {
        let mut store_item_vec: Vec<BusinessItem> = Vec::new();
        store_item_vec.push(item_info);
        <Items<T>>::insert(item_id, who.clone(), store_item_vec);
        Ok(())
    } else {
        Err(<Error<T>>::StoreItemNotFound.into())
    }
});

Will fix your compile error.

Here you see some examples on how to declare the query kind.