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Merged
spacebear21 merged 2 commits into from
Oct 9, 2025
Merged

FFI: Eliminate string fallbacks in error wrappers #1127

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1e4a323
ffi: wrap OHTTP decode errors in typed OhttpError
chavic Oct 1, 2025
ded2e6d
ffi: wrap URI parsing errors without string fallbacks
chavic Oct 1, 2025
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14 changes: 3 additions & 11 deletions payjoin-ffi/src/ohttp.rs
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Original file line number Diff line number Diff line change
@@ -1,17 +1,9 @@
pub use error::OhttpError;

pub mod error {
#[derive(Debug, PartialEq, Eq, thiserror::Error, uniffi::Object)]
#[error("OHTTP error: {message}")]
pub struct OhttpError {
message: String,
}
impl From<ohttp::Error> for OhttpError {
fn from(value: ohttp::Error) -> Self { OhttpError { message: format!("{value:?}") } }
}
impl From<String> for OhttpError {
fn from(value: String) -> Self { OhttpError { message: value } }
}
#[derive(Debug, thiserror::Error, uniffi::Object)]
#[error(transparent)]
pub struct OhttpError(#[from] ohttp::Error);
}

impl From<payjoin::OhttpKeys> for OhttpKeys {
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10 changes: 6 additions & 4 deletions payjoin-ffi/src/uri/error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@ pub struct PjParseError {
msg: String,
}

impl From<String> for PjParseError {
fn from(msg: String) -> Self { PjParseError { msg } }
impl PjParseError {
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@spacebear21 spacebear21 Oct 9, 2025

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I like what you did with OhttpError, changing it to:

pub struct OhttpError(#[from] ohttp::Error);

Is there something preventing us from doing the same thing for PjParseError and PjNotSupported? If yes it would be good to document why we take a different approach for these.

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@chavic chavic Oct 9, 2025

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I went string-backed here because the core payjoin::PjParseError/PjNotSupported don’t currently derive PartialEq/Eq; our fixtures check these errors by comparing values, so swapping to a transparent wrapper would break those comparisons unless we taught the core types how to compare or wrote custom equality glue.
Without those traits, the generated bindings—and our existing tests that compare errors—would break once we stop stringifying.

pub(crate) fn from_err(err: impl std::fmt::Display) -> Self { Self { msg: err.to_string() } }
}

#[derive(Debug, PartialEq, Eq, thiserror::Error, uniffi::Object)]
Expand All @@ -14,8 +14,10 @@ pub struct PjNotSupported {
msg: String,
}

impl From<String> for PjNotSupported {
fn from(msg: String) -> Self { PjNotSupported { msg } }
impl PjNotSupported {
pub(crate) fn from_display(uri: impl std::fmt::Display) -> Self {
Self { msg: uri.to_string() }
}
}

#[derive(Debug, thiserror::Error, uniffi::Object)]
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16 changes: 8 additions & 8 deletions payjoin-ffi/src/uri/mod.rs
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Expand Up @@ -20,10 +20,9 @@ impl From<payjoin::Uri<'static, NetworkChecked>> for Uri {
impl Uri {
#[uniffi::constructor]
pub fn parse(uri: String) -> Result<Self, PjParseError> {
match payjoin::Uri::from_str(uri.as_str()) {
Ok(e) => Ok(e.assume_checked().into()),
Err(e) => Err(e.to_string().into()),
}
payjoin::Uri::from_str(uri.as_str())
.map(|e| e.assume_checked().into())
.map_err(PjParseError::from_err)
}
pub fn address(&self) -> String { self.clone().0.address.to_string() }
/// Gets the amount in satoshis.
Expand All @@ -36,10 +35,11 @@ impl Uri {
}

pub fn check_pj_supported(&self) -> Result<Arc<PjUri>, PjNotSupported> {
match self.0.clone().check_pj_supported() {
Ok(e) => Ok(Arc::new(e.into())),
Err(uri) => Err(uri.to_string().into()),
}
self.0
.clone()
.check_pj_supported()
.map(|uri| Arc::new(uri.into()))
.map_err(PjNotSupported::from_display)
}
pub fn as_string(&self) -> String { self.0.clone().to_string() }
}
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