Trait FormBuilder

Source

pub trait FormBuilder {
    type Output;

    // Required methods
    fn text(&mut self, name: &str, value: &str) -> Result<(), FormError>;
    fn file(&mut self, name: &str, file: FileValue<'_>) -> Result<(), FormError>;
    fn finish(self) -> Result<Self::Output, FormError>;
}

Available on crate feature alloc only.

Expand description

What form! generates, and what a hand-written FromForm implementation provides. Reports problems as FormError::Extract { reason, field }.

§Examples

use form_net::{ExtractError, FileValue, FormBuilder, FormError, FromForm};

/// Accepts any field names, keeping the last `q`.
#[derive(Default)]
struct LastQ(Option<String>);

impl FormBuilder for LastQ {
    type Output = Query;
    fn text(&mut self, name: &str, value: &str) -> Result<(), FormError> {
        if name == "q" { self.0 = Some(value.to_owned()); }
        Ok(())
    }
    fn file(&mut self, _name: &str, _file: FileValue<'_>) -> Result<(), FormError> {
        Err(FormError::Extract { reason: ExtractError::WrongKind, field: Some("q") })
    }
    fn finish(self) -> Result<Query, FormError> {
        Ok(Query { q: self.0.unwrap_or_default() })
    }
}

struct Query { q: String }
impl FromForm for Query { type Builder = LastQ; }

assert_eq!(Query::from_query(b"q=a&q=b")?.q, "b");