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Events

Version 1.0.0

Summary

Standard interface for NFT contract actions. Extension of NEP-297

Motivation

NEAR and third-party applications need to track mint, transfer, burn events for all NFT-driven apps consistently. This extension addresses that.

Keep in mind that applications, including NEAR Wallet, could require implementing additional methods to display the NFTs correctly, such as nft_metadata and nft_tokens_for_owner.

Interface

Non-Fungible Token Events MUST have standard set to "nep171", standard version set to "1.0.0", event value is one of nft_mint, nft_burn, nft_transfer, and data must be of one of the following relavant types: NftMintLog[] | NftTransferLog[] | NftBurnLog[]:

interface NftEventLogData {
standard: "nep171",
version: "1.0.0",
event: "nft_mint" | "nft_burn" | "nft_transfer",
data: NftMintLog[] | NftTransferLog[] | NftBurnLog[],
}
// An event log to capture token minting
// Arguments
// * `owner_id`: "account.near"
// * `token_ids`: ["1", "abc"]
// * `memo`: optional message
interface NftMintLog {
owner_id: string,
token_ids: string[],
memo?: string
}

// An event log to capture token burning
// Arguments
// * `owner_id`: owner of tokens to burn
// * `authorized_id`: approved account_id to burn, if applicable
// * `token_ids`: ["1","2"]
// * `memo`: optional message
interface NftBurnLog {
owner_id: string,
authorized_id?: string,
token_ids: string[],
memo?: string
}

// An event log to capture token transfer
// Arguments
// * `authorized_id`: approved account_id to transfer, if applicable
// * `old_owner_id`: "owner.near"
// * `new_owner_id`: "receiver.near"
// * `token_ids`: ["1", "12345abc"]
// * `memo`: optional message
interface NftTransferLog {
authorized_id?: string,
old_owner_id: string,
new_owner_id: string,
token_ids: string[],
memo?: string
}

Examples

Single owner batch minting (pretty-formatted for readability purposes):

EVENT_JSON:{
"standard": "nep171",
"version": "1.0.0",
"event": "nft_mint",
"data": [
{"owner_id": "foundation.near", "token_ids": ["aurora", "proximitylabs"]}
]
}

Different owners batch minting:

EVENT_JSON:{
"standard": "nep171",
"version": "1.0.0",
"event": "nft_mint",
"data": [
{"owner_id": "foundation.near", "token_ids": ["aurora", "proximitylabs"]},
{"owner_id": "user1.near", "token_ids": ["meme"]}
]
}

Different events (separate log entries):

EVENT_JSON:{
"standard": "nep171",
"version": "1.0.0",
"event": "nft_burn",
"data": [
{"owner_id": "foundation.near", "token_ids": ["aurora", "proximitylabs"]},
]
}
EVENT_JSON:{
"standard": "nep171",
"version": "1.0.0",
"event": "nft_transfer",
"data": [
{"old_owner_id": "user1.near", "new_owner_id": "user2.near", "token_ids": ["meme"], "memo": "have fun!"}
]
}

Authorized id:

EVENT_JSON:{
"standard": "nep171",
"version": "1.0.0",
"event": "nft_burn",
"data": [
{"owner_id": "owner.near", "token_ids": ["goodbye", "aurevoir"], "authorized_id": "thirdparty.near"}
]
}

Further methods

Note that the example events covered above cover two different kinds of events:

  1. Events that are not specified in the NFT Standard (nft_mint, nft_burn)
  2. An event that is covered in the NFT Core Standard. (nft_transfer)

This event standard also applies beyond the three events highlighted here, where future events follow the same convention of as the second type. For instance, if an NFT contract uses the approval management standard, it may emit an event for nft_approve if that's deemed as important by the developer community.

Please feel free to open pull requests for extending the events standard detailed here as needs arise.