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Add depythonize_on_error #38

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Add depythonize_on_error #38

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f8f270a
Add depythonize_on_error
LilyFoote Mar 1, 2023
9407d4a
Don't serialize bytes
LilyFoote Mar 1, 2023
b75ae91
Remove default handling of set and frozenset
LilyFoote Mar 2, 2023
14fda88
Convert non-string keys to strings
LilyFoote Mar 2, 2023
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79 changes: 58 additions & 21 deletions src/de.rs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
use pyo3::intern;
use pyo3::types::*;
use serde::de::{self, IntoDeserializer};
use serde::Deserialize;
Expand All @@ -9,17 +10,30 @@ pub fn depythonize<'de, T>(obj: &'de PyAny) -> Result<T>
where
T: Deserialize<'de>,
{
let mut depythonizer = Depythonizer::from_object(obj);
let mut depythonizer = Depythonizer::from_object(obj, &None);
T::deserialize(&mut depythonizer)
}

/// Attempt to convert a Python object to an instance of `T`
pub fn depythonize_on_error<'de, T>(
obj: &'de PyAny,
on_error: &'de Option<fn(&PyAny) -> &PyAny>,
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I haven't thought deeply about whether a different lifetime might be appropriate for on_error.

) -> Result<T>
where
T: Deserialize<'de>,
{
let mut depythonizer = Depythonizer::from_object(obj, on_error);
T::deserialize(&mut depythonizer)
}

pub struct Depythonizer<'de> {
input: &'de PyAny,
on_error: &'de Option<fn(&PyAny) -> &PyAny>,
}

impl<'de> Depythonizer<'de> {
pub fn from_object(input: &'de PyAny) -> Self {
Depythonizer { input }
pub fn from_object(input: &'de PyAny, on_error: &'de Option<fn(&PyAny) -> &PyAny>) -> Self {
Depythonizer { input, on_error }
}

fn sequence_access(&self, expected_len: Option<usize>) -> Result<PySequenceAccess<'de>> {
Expand All @@ -30,12 +44,12 @@ impl<'de> Depythonizer<'de> {
Some(expected) if expected != len => {
Err(PythonizeError::incorrect_sequence_length(expected, len))
}
_ => Ok(PySequenceAccess::new(seq, len)),
_ => Ok(PySequenceAccess::new(seq, len, self.on_error)),
}
}

fn dict_access(&self) -> Result<PyMappingAccess<'de>> {
PyMappingAccess::new(self.input.downcast()?)
PyMappingAccess::new(self.input.downcast()?, self.on_error)
}
}

Expand Down Expand Up @@ -63,22 +77,16 @@ impl<'a, 'de> de::Deserializer<'de> for &'a mut Depythonizer<'de> {
self.deserialize_unit(visitor)
} else if obj.is_instance_of::<PyBool>()? {
self.deserialize_bool(visitor)
} else if obj.is_instance_of::<PyByteArray>()? || obj.is_instance_of::<PyBytes>()? {
self.deserialize_bytes(visitor)
Comment on lines -66 to -67
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I removed this because it was the quickest and easiest way to use the on_error callback when handling a bytes object. Obviously this breaks other use cases of this library, so a different solution will be needed here.

} else if obj.is_instance_of::<PyDict>()? {
self.deserialize_map(visitor)
} else if obj.is_instance_of::<PyFloat>()? {
self.deserialize_f64(visitor)
} else if obj.is_instance_of::<PyFrozenSet>()? {
self.deserialize_tuple(obj.len()?, visitor)
} else if obj.is_instance_of::<PyInt>()? {
self.deserialize_i64(visitor)
} else if obj.is_instance_of::<PyList>()? {
self.deserialize_tuple(obj.len()?, visitor)
} else if obj.is_instance_of::<PyLong>()? {
self.deserialize_i64(visitor)
} else if obj.is_instance_of::<PySet>()? {
self.deserialize_tuple(obj.len()?, visitor)
} else if obj.is_instance_of::<PyString>()? {
self.deserialize_str(visitor)
} else if obj.is_instance_of::<PyTuple>()? {
Expand All @@ -90,9 +98,17 @@ impl<'a, 'de> de::Deserializer<'de> for &'a mut Depythonizer<'de> {
} else if obj.downcast::<PyMapping>().is_ok() {
self.deserialize_map(visitor)
} else {
Err(PythonizeError::unsupported_type(
obj.get_type().name().unwrap_or("<unknown>"),
))
match self.on_error {
Some(on_error) => {
// Do we recurse infinitely if on_error returns something we can't
// deserialize?
self.input = on_error(self.input);
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I'm not certain that reassigning to self.input here is appropriate. Maybe that could break serializing some nested data?

Comment on lines +103 to +105
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I'm not sure how best to avoid this infinite recursion.

self.deserialize_any(visitor)
}
None => Err(PythonizeError::unsupported_type(
obj.get_type().name().unwrap_or("<unknown>"),
)),
}
}
}

Expand Down Expand Up @@ -259,7 +275,7 @@ impl<'a, 'de> de::Deserializer<'de> for &'a mut Depythonizer<'de> {
.downcast()
.map_err(|_| PythonizeError::dict_key_not_string())?;
let value = d.get_item(variant).unwrap();
let mut de = Depythonizer::from_object(value);
let mut de = Depythonizer::from_object(value, self.on_error);
visitor.visit_enum(PyEnumAccess::new(&mut de, variant))
} else if item.is_instance_of::<PyString>()? {
let s: &PyString = self.input.downcast()?;
Expand Down Expand Up @@ -292,11 +308,17 @@ struct PySequenceAccess<'a> {
seq: &'a PySequence,
index: usize,
len: usize,
on_error: &'a Option<fn(&PyAny) -> &PyAny>,
}

impl<'a> PySequenceAccess<'a> {
fn new(seq: &'a PySequence, len: usize) -> Self {
Self { seq, index: 0, len }
fn new(seq: &'a PySequence, len: usize, on_error: &'a Option<fn(&PyAny) -> &PyAny>) -> Self {
Self {
seq,
index: 0,
len,
on_error,
}
}
}

Expand All @@ -308,7 +330,8 @@ impl<'de> de::SeqAccess<'de> for PySequenceAccess<'de> {
T: de::DeserializeSeed<'de>,
{
if self.index < self.len {
let mut item_de = Depythonizer::from_object(self.seq.get_item(self.index)?);
let mut item_de =
Depythonizer::from_object(self.seq.get_item(self.index)?, self.on_error);
self.index += 1;
seed.deserialize(&mut item_de).map(Some)
} else {
Expand All @@ -323,10 +346,11 @@ struct PyMappingAccess<'de> {
key_idx: usize,
val_idx: usize,
len: usize,
on_error: &'de Option<fn(&PyAny) -> &PyAny>,
}

impl<'de> PyMappingAccess<'de> {
fn new(map: &'de PyMapping) -> Result<Self> {
fn new(map: &'de PyMapping, on_error: &'de Option<fn(&PyAny) -> &PyAny>) -> Result<Self> {
let keys = map.keys()?;
let values = map.values()?;
let len = map.len()?;
Expand All @@ -336,6 +360,7 @@ impl<'de> PyMappingAccess<'de> {
key_idx: 0,
val_idx: 0,
len,
on_error,
})
}
}
Expand All @@ -348,7 +373,18 @@ impl<'de> de::MapAccess<'de> for PyMappingAccess<'de> {
K: de::DeserializeSeed<'de>,
{
if self.key_idx < self.len {
let mut item_de = Depythonizer::from_object(self.keys.get_item(self.key_idx)?);
let key = self.keys.get_item(self.key_idx)?;
let py = key.py();
let key = match key {
key if key.is_instance_of::<PyUnicode>()? => key,
key if key.is_none() => intern!(py, "null"),
key if key.is_instance_of::<PyBool>()? => match key.is_true()? {
true => intern!(py, "true"),
false => intern!(py, "false"),
},
key => key.str()?,
Comment on lines +378 to +385
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Here I'm (mostly) matching the behaviour of json.dumps that converts "dict keys of a basic type" (str, int, float, bool, None) to strings.

Again, this probably shouldn't live here, but I'm not clear what the right approach is.

};
let mut item_de = Depythonizer::from_object(key, self.on_error);
self.key_idx += 1;
seed.deserialize(&mut item_de).map(Some)
} else {
Expand All @@ -360,7 +396,8 @@ impl<'de> de::MapAccess<'de> for PyMappingAccess<'de> {
where
V: de::DeserializeSeed<'de>,
{
let mut item_de = Depythonizer::from_object(self.values.get_item(self.val_idx)?);
let mut item_de =
Depythonizer::from_object(self.values.get_item(self.val_idx)?, self.on_error);
self.val_idx += 1;
seed.deserialize(&mut item_de)
}
Expand Down
2 changes: 1 addition & 1 deletion src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ mod de;
mod error;
mod ser;

pub use crate::de::depythonize;
pub use crate::de::{depythonize, depythonize_on_error};
pub use crate::error::{PythonizeError, Result};
pub use crate::ser::{
pythonize, pythonize_custom, PythonizeDictType, PythonizeListType, PythonizeTypes,
Expand Down