Trait serde::de::Expected

pub trait Expected {
    fn fmt(&self, formatter: &mut Formatter) -> Result;
}

Expected represents an explanation of what data a Visitor was expecting to receive.

This is used as an argument to the invalid_type, invalid_value, and invalid_length methods of the Error trait to build error messages. The message should be a noun or noun phrase that completes the sentence "This Visitor expects to receive ...", for example the message could be "an integer between 0 and 64". The message should not be capitalized and should not end with a period.

Within the context of a Visitor implementation, the Visitor itself (&self) is an implementation of this trait.

fn visit_bool<E>(self, v: bool) -> Result<Self::Value, E>
    where E: de::Error
{
    Err(de::Error::invalid_type(Unexpected::Bool(v), &self))
}

Outside of a Visitor, &"..." can be used.

return Err(de::Error::invalid_type(Unexpected::Bool(v), &"a negative integer"));

Required Methods

fn fmt(&self, formatter: &mut Formatter) -> Result

Format an explanation of what data was being expected. Same signature as the Display and Debug traits.

Trait Implementations

impl<'a> Display for Expected + 'a

fn fmt(&self, formatter: &mut Formatter) -> Result

Formats the value using the given formatter.

Implementors

• impl<'de, T> Expected for T where T: Visitor<'de>
• impl<'a> Expected for &'a str