Assertions

Like every program, bugs can occur and user input must be validated. Vaulta provides a clear cut way to do this.

Reverting state

Assertions are a way to check that a condition is true, and if it is not, the transaction will fail. When a transaction fails, all state changes that have occurred in the transaction will be rolled back. This means that any changes to persisted data / tables will be reverted as if the transaction never happened.

Check

The check function is how you validate conditions in Vaulta. The function will check that the specified condition is true, and if it is not, the transaction will fail.

check(1 == 1, "1 should equal 1");

The interface for the check function simply takes a condition and a string message. If the condition is false, the message will be thrown as an error and the transaction will revert.

Logging non-strings

Since the check function takes a string message, you might be wondering how to log non-strings. This depends on the type of data you want to log, but here are some common examples:

Logging name

name thisContract = get_self();
check(false, "This contract is: " + thisContract.to_string());

Logging asset

asset myAsset = asset(100, symbol("A", 4));
check(false, "My asset is: " + myAsset.to_string());

Logging integers

int myInt = 100;
check(false, "My int is: " + std::to_string(myInt));