I want to implement NFT purchasing function in the marketplace based on a substrate node

Question

Now I am trying to implement NFT purchasing functionality based on a substrate node.

I got this function from the polkadot js documentation.

buyItem(collection: u32, item: u32, bid_price: u128)

    interface: api.tx.uniques.buyItem
    summary: See [Pallet::buy_item]. 

but when I try this function. I got this (the image)

Of course, the function caller is a buyer.

I hope to get any advice to get this works.

Answer 1

Looks like there are two checks in buy_item that result in NoPermission:

ensure!(details.owner != buyer, Error::<T, I>::NoPermission);

The owner is not allowed to buy the NFT.

if let Some(only_buyer) = price_info.1 {
    ensure!(only_buyer == buyer, Error::<T, I>::NoPermission);
}

There is a whitelisted_buyer and only they are allowed to buy the NFT.