ft-get-balance

Function Signature

(ft-get-balance token-name principal)

• Input:
  • token-name: The name of the fungible token
  • principal: The principal whose balance to check
• Output: uint

Why it matters

The ft-get-balance function is crucial for:

1. Querying the current balance of a fungible token for any principal.
2. Implementing balance checks before transfers or other token operations.
3. Providing transparency and visibility into token holdings.
4. Enabling other contracts or off-chain applications to verify token balances.

When to use it

Use ft-get-balance when you need to:

• Check a user's token balance before performing operations.
• Implement balance-dependent logic in your contract.
• Provide balance information to users or other contracts.
• Verify sufficient funds for token transfers or burns.

Best Practices

• Use ft-get-balance before attempting transfers to ensure sufficient balance.
• Consider caching balance results if queried frequently to optimize gas usage.
• Be aware that balances can change between checks and actual token operations.
• Use in combination with other ft-* functions for comprehensive token management.

Practical Example: Balance Check Before Transfer

Let's implement a function that checks balance before transferring tokens:

(define-fungible-token my-token)

(define-public (transfer-if-sufficient (amount uint) (recipient principal))
  (let ((sender-balance (ft-get-balance my-token tx-sender)))
    (if (>= sender-balance amount)
        (ft-transfer? my-token amount tx-sender recipient)
        (err u1))))

;; Usage
(ft-mint? my-token u100 tx-sender)
(transfer-if-sufficient u50 'SPAXYA5XS51713FDTQ8H94EJ4V579CXMTRNBZKSF) ;; Returns (ok true)
(ft-get-balance my-token tx-sender) ;; Returns u50

This example demonstrates:

1. Using ft-get-balance to check the sender's balance before attempting a transfer.
2. Implementing a conditional transfer based on the balance check.
3. Combining ft-get-balance with other ft-* functions for token management.

Common Pitfalls

1. Assuming balances remain constant between checking and performing operations.
2. Not handling the case where a principal might not have any balance (returns 0).
3. Overusing ft-get-balance in loops, which can be inefficient for gas consumption.

Related Functions

• ft-transfer?: Used to transfer tokens between principals.
• ft-mint?: Used to create new tokens, increasing the balance of a principal.
• ft-burn?: Used to destroy tokens, decreasing the balance of a principal.
• ft-get-supply: Used to get the current total supply of tokens.

Conclusion

The ft-get-balance function is a fundamental tool for managing fungible tokens in Clarity smart contracts. It provides a straightforward way to query token balances, enabling developers to implement robust token-based systems with proper balance checks and validations. When used effectively in combination with other token functions, it ensures the integrity and accuracy of token operations within your smart contracts.