Hands-On Microservices with Rust

Custom deserialization

Our Color type has to be convertible from a string. We can do this by implementing the FromStr trait, which makes it possible to call the parse method of str to parse the struct from a string:

impl FromStr for Color {    type Err = ColorError;    fn from_str(s: &str) -> Result<Self, Self::Err> {        match s {            "white" => Ok(WHITE.to_owned()),            "black" => Ok(BLACK.to_owned()),            s if s.starts_with("#") && s.len() == 7 => {                let red = u8::from_str_radix(&s[1..3], 16)?;                let green = u8::from_str_radix(&s[3..5], 16)?;                let blue = u8::from_str_radix(&s[5..7], 16)?;                Ok(Color { red, green, blue })            },            other => {                Err(ColorError::InvalidValue { value: other.to_owned() })            },        }    }}

In this implementation, we use a match expression with four branches ...