Can token balance be accessed in provable code? | Mina Protocol | Page 1

rocky adder Nov 17, 2023, 6:34 PM

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const currentTokenBalance = Mina.getBalance(this.sender, this.tokenId); throws on compile for me, since it seems like it calls non-provable code:

at toConstantField (o1js/src/lib/field.ts:1332:9)
at Function.toBase58 (o1js/src/lib/signature.ts:203:9)
at PublicKey.toBase58 (o1js/src/lib/signature.ts:195:22)
at Module.markAccountToBeFetched (o1js/src/lib/fetch.ts:266:35)
at Object.getAccount (o1js/src/lib/mina.ts:1019:13)
at Module.getBalance (o1js/src/lib/mina.ts:1191:25)

Is there a version that can be called in provable code? Or can I set a precondition that some private input must be the on-chain state for a given token balance?

idle marsh Nov 17, 2023, 6:38 PM

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  @method verifyBadge(nft: PublicKey, nftTokenId: Field) {
    const account = Account(nft, this.token.id);
    const tokenBalance = account.balance.getAndAssertEquals();

    const minanft = new MinaNFTContract(nft, nftTokenId);
    const version = minanft.version.getAndAssertEquals();

    version.assertEquals(tokenBalance);
  }

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#1171202435663007804 message

rocky adder Nov 17, 2023, 6:42 PM

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Thank you!

idle marsh Nov 17, 2023, 6:49 PM

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Please also note that this code works only when you access one token balance and breaks or gives wrong results with two different tokens: https://github.com/o1-labs/o1js/issues/1245

rocky adder Nov 17, 2023, 6:50 PM

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Nice one, you are really putting the network through its paces 🙂

#Can token balance be accessed in provable code?