Mutating Storage Values

It's time to modify some storage!

Mutable and Immutable Functions

You may have noticed that the function template included self as the first parameter of the contract functions. It is through self that you gain access to all your contract functions and storage items.

If you are simply reading from the contract storage, you only need to pass &self. But if you want to modify storage items, you will need to explicitly mark it as mutable, &mut self.

impl MyContract {
    #[ink(message)]
    pub fn my_getter(&self) -> u32 {
        self.my_number
    }

    #[ink(message)]
    pub fn my_setter(&mut self, new_value: u32) {
        self.my_number = new_value;
    }
}