[英]How do I save a string value on Substrate's smart contract platform, ink?
cargo +nightly generate-metadata
使用ink_prelude::string::String
#![cfg_attr(not(feature = "std"), no_std)]
use ink_lang as ink;
#[ink::contract]
mod foo {
use ink_prelude::string::String;
// ...
}
並且不要忘記將ink_prelude添加到.toml中的[dependencies]部分
參見: https://paritytech.github.io/ink/ink_prelude/string/struct.String.html
用墨水! 你可以直接使用String
類型。
這是墨水的簡單實現! 合同通過測試執行此操作(從incrementer
示例修改:
#![cfg_attr(not(feature = "std"), no_std)]
use ink_lang as ink;
#[ink::contract(version = "0.1.0")]
mod basic_string {
#[ink(storage)]
struct BasicString {
value: String,
}
impl BasicString {
#[ink(constructor)]
fn new(init_value: String) -> Self {
Self { value: init_value }
}
#[ink(constructor)]
fn default() -> Self {
Self::new(Default::default())
}
#[ink(message)]
fn set(&mut self, new: String) {
self.value = new;
}
#[ink(message)]
fn get(&self) -> String {
self.value.clone()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn default_works() {
let contract = BasicString::default();
assert_eq!(contract.get(), "");
}
#[test]
fn it_works() {
let mut contract = BasicString::new("Hello World!".into());
assert_eq!(contract.get(), "Hello World!");
contract.set("Goodbye!".into());
assert_eq!(contract.get(), "Goodbye!");
}
}
}
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