darling_core/options/
forwarded_field.rs

1use syn::{Ident, Path};
2
3use crate::{Error, FromField, FromMeta};
4
5use super::ParseAttribute;
6
7/// A forwarded field and attributes that influence its behavior.
8#[derive(Debug, Clone)]
9pub struct ForwardedField {
10    /// The ident of the field that will receive the forwarded value.
11    pub ident: Ident,
12    /// Path of the function that will be called to convert the forwarded value
13    /// into the type expected by the field in `ident`.
14    pub with: Option<Path>,
15}
16
17impl FromField for ForwardedField {
18    fn from_field(field: &syn::Field) -> crate::Result<Self> {
19        let result = Self {
20            ident: field.ident.clone().ok_or_else(|| {
21                Error::custom("forwarded field must be named field").with_span(field)
22            })?,
23            with: None,
24        };
25
26        result.parse_attributes(&field.attrs)
27    }
28}
29
30impl ParseAttribute for ForwardedField {
31    fn parse_nested(&mut self, mi: &syn::Meta) -> crate::Result<()> {
32        if mi.path().is_ident("with") {
33            if self.with.is_some() {
34                return Err(Error::duplicate_field_path(mi.path()).with_span(mi));
35            }
36
37            self.with = FromMeta::from_meta(mi)?;
38            Ok(())
39        } else {
40            Err(Error::unknown_field_path_with_alts(mi.path(), &["with"]).with_span(mi))
41        }
42    }
43}
darling_core/options/forwarded_field.rs

darling_core/options/
forwarded_field.rs
