How to handle String.parse<_> ParseIntError [rust] - rust

Question

I finished converting the Rust books guessing game example to an Iced GUI application and wanted to handle error handling for the input from the user.
I have a String trying to convert to an i32 and am not sure how to handle the error if the user puts a String in the text_input or just hits return. I figured out a simple solution of:
self.hidden_compare = self.user_guess_text.trim().parse::<i32>().unwrap_or(0);
Rather than having self.hidden_compare default to 0. I would rather have self.user_guess_text default to a String I have set to earlier in the application and am unsure of how to accomplish this still being fairly new.
Edit: Full function added for clarification.
fn update(&mut self, message: Message) -> Command<Message> {
match message {
Message::BtnGuessNow => {
self.hidden_compare = self.user_guess_text.trim().parse::<i32>().unwrap_or(0);
if self.hidden_value == self.hidden_compare {
self.label_compare = String::from("A WINNER!");
self.number_ofguesses.push(self.hidden_compare.to_string() + ", A WINNER!");
}
else if self.hidden_value > self.hidden_compare {
self.label_compare = String::from("Too Low");
self.number_ofguesses.push(self.hidden_compare.to_string() + ", Too Low!");
}
else if self.hidden_value < self.hidden_compare {
self.label_compare = String::from("Too Big");
self.number_ofguesses.push(self.hidden_compare.to_string()+ ", Too Big!");
}
self.user_guess_text = "".to_string();
Command::none()
}
Message::UserInputValueUpdate(x) => {
self.user_guess_text = x;
Command::none()
}
}
and a relevant function that handles the Vec output:
fn guess_output_calc(&self) -> String {
let mut tempoutput = String::new();
for (i, x) in self.number_ofguesses.iter().enumerate().skip(1) {
let guessfmt = String::from(format!("Guess# {} Was: {}\n", i, x));
tempoutput.push_str(&guessfmt);
};
return

Answer 1

I would rather have self.user_guess_text default to a String
I'm not entirely sure what you mean with that, but I interpret this as "I want to set the self.user_guess_text variable to a specific value if it can't be converted to an integer". If this is wrong, then please update your question.
This is how I would approach this (simplified):
fn main() {
let mut user_guess_text = " a ";
match user_guess_text.trim().parse::<i32>() {
Ok(value) => {
println!("Parsed to value: {}", value);
}
Err(_) => {
println!("Unable to parse. Resetting variable.");
user_guess_text = "fallback text!";
}
}
println!("user_guess_text: {}", user_guess_text);
}
Unable to parse. Resetting variable.
user_guess_text: default text!