谁是 nft_transfer_call 中的接收者？

Posted 2023-02-14

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【中文标题】谁是 nft_transfer_call 中的接收者？【英文标题】：Who is the receiver in a nft_transfer_call? 【发布时间】：2021-10-08 15:06:46 【问题描述】：

我有一个NFT 合约和一个Market 部署它。我没有使用nft_transfer_call 接受出价，但现在将其添加。在NFT/Media 所有者接受投标的情况下，当前实施的流程是：

[nft-contract].accept_bid(token_id, bidder)

[market-contract].xcc_market_accept_bid(token_id, bidder, design.creator, design.owner_id, design.prev_owner)

NFT

[nft-contract].xcc_media_nft_transfer(token_id, receiver_id)

NFT

Media

我知道这不是正确的方法，因为我应该使用 nft_transfer_call，根据标准，这就是我理解的上述调用的方式：

[nft-contract].nft_transfer_call(
  "receiver_id": $market_address, ? or $bidder
  "token_id": $token_id,
  "msg": "$token_id $bidder $creator $owner_id $prev_owner"
)

应该在内部传输令牌然后触发：

[market-contract].nft_on_transfer(
  "sender_id": $sender_of_nft_transfer_call,
  "previous_owner_id": $get_media_prev_owner_from_store,
  "token_id": $token_id_passed_by_front_end,
  "msg": "$token_id $bidder $creator $owner_id $prev_owner", // parameters for Market contract
)

分配支出、更新新股并最终回调：

[nft-contract].nft_resolve_transfer(
  "sender_id": $sender_of_nft_transfer_call,
  "receiver_id":  $market_address, ? or $bidder,
  "token_id": $token_id,
)

问题是在这种情况下receiver_id 是谁（市场还是新所有者）？我知道审批管理标准在这里可能是更好的解决方案，但我试图保持简单并通过转接电话解决它。

Market interface

【问题讨论】：

【参考方案1】：

如果我正确阅读了您的代码，bidder 是两个函数中receiver_id 的值。来自 [docs][1]：

// * `receiver_id`: the valid NEAR account receiving the token

// Arguments:
// * `receiver_id`: the valid NEAR account receiving the token.
// * `token_id`: the token to send.
// * `approval_id`: expected approval ID. A number smaller than
//    2^53, and therefore representable as JSON. See Approval Management
//    standard for full explanation.
// * `memo` (optional): for use cases that may benefit from indexing or
//    providing information for a transfer.
// * `msg`: specifies information needed by the receiving contract in
//    order to properly handle the transfer. Can indicate both a function to
//    call and the parameters to pass to that function.
function nft_transfer_call(
  receiver_id: string,
  token_id: string,
  approval_id: number|null,
  memo: string|null,
  msg: string,
): Promise

应该匹配nft_resolve_transfer()中的参数

// * `receiver_id`: the `receiver_id` argument given to `nft_transfer_call`

    // Arguments:
// * `sender_id`: the sender of `ft_transfer_call`
// * `receiver_id`: the `receiver_id` argument given to `nft_transfer_call`
// * `token_id`: the `token_id` argument given to `ft_transfer_call`
// * `approved_token_ids`: if using Approval Management, contract MUST provide
//   set of original approved accounts in this argument, and restore these
//   approved accounts in case of revert.
//
// Returns true if token was successfully transferred to `receiver_id`.
function nft_resolve_transfer(
  owner_id: string,
  receiver_id: string,
  token_id: string,
  approved_account_ids: null|string[],
): boolean 


  [1]: https://nomicon.io/Standards/NonFungibleToken/Core.html

【讨论】：

这是正确的。我注意到在这些 cmets 中阅读代码并不容易，因此我将在单独的答案中进行扩展。对于可能会发现这一点的人，请注意 BenTheHumanMan 在这里引用了 Nomicon 规范文档：nomicon.io/Standards/NonFungibleToken/Core.html#nft-interface【参考方案2】：

正如 BenTheHumanMan 所说，receiver_id 将是相同的。

这是来自 Rust 示例的 sn-p：

fn nft_transfer_call(
    &mut self,
    receiver_id: AccountId,
    token_id: TokenId,
    approval_id: Option<u64>,
    memo: Option<String>,
    msg: String,
) -> PromiseOrValue<bool> 
    assert_one_yocto();
    let sender_id = env::predecessor_account_id();
    let (old_owner, old_approvals) =
        self.internal_transfer(&sender_id, &receiver_id, &token_id, approval_id, memo);
    // Initiating receiver's call and the callback
    ext_receiver::nft_on_transfer(
        sender_id.clone(),
        old_owner.clone(),
        token_id.clone(),
        msg,
        &receiver_id,
        NO_DEPOSIT,
        env::prepaid_gas() - GAS_FOR_FT_TRANSFER_CALL,
    )
    .then(ext_self::nft_resolve_transfer(
        old_owner,
        receiver_id,
        token_id,
        old_approvals,
        &env::current_account_id(),
        NO_DEPOSIT,
        GAS_FOR_RESOLVE_TRANSFER,
    ))
    .into()

请注意，我们使用的是最初提供给函数的 receiver_id，然后将其传递给回调 (nft_resolve_transfer)。

但也许为了更直接地回答您的问题……如果您让人们对 NFT 进行投标，则可能不需要使用转接和呼叫功能。在不了解出价如何运作的详细信息的情况下，我认为您说得对，批准更合适。

有一个示例in Nomicon 可能会有所帮助。请注意，这链接到可替代令牌而不是不可替代令牌，因为我相信这更容易理解。链接页面涉及以下场景：