1 unstable release
0.1.0-alpha.1 | Feb 1, 2023 |
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#90 in #original
Used in bs721-base
19KB
294 lines
BS721 Spec: Non Fungible Tokens
BS721 is a specification for non-fungible tokens based on CosmWasm 721. The name and design is based on Ethereum's ERC721 standard, with some enhancements. The types in here can be imported by contracts that wish to implement this spec, or by contracts that call to any standard bs721 contract.
The specification is split into multiple sections, a contract may only implement some of this functionality, but must implement the base.
Base
This handles ownership, transfers, and allowances. These must be supported as is by all BS721 contracts. Note that all tokens must have an owner, as well as an ID. The ID is an arbitrary string, unique within the contract.
Messages
TransferNft{recipient, token_id}
-
This transfers ownership of the token to recipient
account. This is
designed to send to an address controlled by a private key and does not
trigger any actions on the recipient if it is a contract.
Requires token_id
to point to a valid token, and env.sender
to be
the owner of it, or have an allowance to transfer it.
SendNft{contract, token_id, msg}
-
This transfers ownership of the token to contract
account. contract
must be an address controlled by a smart contract, which implements
the Bs721Receiver interface. The msg
will be passed to the recipient
contract, along with the token_id.
Requires token_id
to point to a valid token, and env.sender
to be
the owner of it, or have an allowance to transfer it.
Approve{spender, token_id, expires}
- Grants permission to spender
to
transfer or send the given token. This can only be performed when
env.sender
is the owner of the given token_id
or an operator
.
There can be multiple spender accounts per token, and they are cleared once
the token is transferred or sent.
Revoke{spender, token_id}
- This revokes a previously granted permission
to transfer the given token_id
. This can only be granted when
env.sender
is the owner of the given token_id
or an operator
.
ApproveAll{operator, expires}
- Grant operator
permission to transfer or send
all tokens owned by env.sender
. This approval is tied to the owner, not the
tokens and applies to any future token that the owner receives as well.
RevokeAll{operator}
- Revoke a previous ApproveAll
permission granted
to the given operator
.
Queries
OwnerOf{token_id, include_expired}
- Returns the owner of the given token,
as well as anyone with approval on this particular token. If the token is
unknown, returns an error. Return type is OwnerOfResponse
. If
include_expired
is set, show expired owners in the results, otherwise, ignore
them.
Approval{token_id, spender, include_expired}
- Return an approval of spender
about the given token_id
. Return type is ApprovalResponse
. If
include_expired
is set, show expired owners in the results, otherwise, ignore
them.
Approvals{token_id, include_expired}
- Return all approvals that owner given
access to. Return type is ApprovalsResponse
. If include_expired
is set, show
expired owners in the results, otherwise, ignore them.
AllOperators{owner, include_expired, start_after, limit}
- List all
operators that can access all of the owner's tokens. Return type is
OperatorsResponse
. If include_expired
is set, show expired owners in the
results, otherwise, ignore them. If start_after
is set, then it returns the
first limit
operators after the given one.
NumTokens{}
- Total number of tokens issued
Receiver
The counter-part to SendNft
is ReceiveNft
, which must be implemented by
any contract that wishes to manage BS721 tokens. This is generally not
implemented by any BS721 contract.
ReceiveNft{sender, token_id, msg}
- This is designed to handle SendNft
messages. The address of the contract is stored in env.sender
so it cannot be faked. The contract should ensure the sender matches
the token contract it expects to handle, and not allow arbitrary addresses.
The sender
is the original account requesting to move the token
and msg
is a Binary
data that can be decoded into a contract-specific
message. This can be empty if we have only one default action,
or it may be a ReceiveMsg
variant to clarify the intention. For example,
if I send to an exchange, I can specify the price I want to list the token
for.
Metadata
Queries
ContractInfo{}
- This returns top-level metadata about the contract.
Namely, name
, symbol
and uri
.
NftInfo{token_id}
- This returns metadata about one particular token.
The return value is based on ERC721 Metadata JSON Schema, but directly
from the contract, not as a Uri. Only the image link is a Uri.
AllNftInfo{token_id}
- This returns the result of both NftInfo
and OwnerOf
as one query as an optimization for clients, which may
want both info to display one NFT.
Enumerable
Queries
Pagination is achieved via start_after
and limit
. Limit is a request
set by the client, if unset, the contract will automatically set it to
DefaultLimit
(suggested 10). If set, it will be used up to a MaxLimit
value (suggested 30). Contracts can define other DefaultLimit
and MaxLimit
values without violating the BS721 spec, and clients should not rely on
any particular values.
If start_after
is unset, the query returns the first results, ordered
lexicographically by token_id
. If start_after
is set, then it returns the
first limit
tokens after the given one. This allows straightforward
pagination by taking the last result returned (a token_id
) and using it
as the start_after
value in a future query.
Tokens{owner, start_after, limit}
- List all token_ids that belong to a given owner.
Return type is TokensResponse{tokens: Vec<token_id>}
.
AllTokens{start_after, limit}
- Requires pagination. Lists all token_ids controlled by
the contract.
Dependencies
~4–6MB
~125K SLoC