Crate serde_pickle_rs

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Expand description

Serialization and deserialization for Python’s pickle format

Pickle format

Please see the Python docs for details on the Pickle format.

This crate supports all Pickle protocols (0 to 5) when reading, and writing protocol 2 (compatible with Python 2 and 3), or protocol 3 (compatible with Python 3 only).

Supported types

Pickle is very powerful. It is capable of serializing pretty arbitrary graphs of Python objects, with most custom classes being serialized out of the box. Currently, this crate only supports Python’s built-in types that map easily to Rust constructs. There are:

  • None
  • Boolean (Rust bool)
  • Integers (Rust i64 or bigints from num)
  • Floats (Rust f64)
  • Bytes objects and bytearrays (see below)
  • (Unicode) strings (Rust String)
  • Lists and tuples (Rust Vec<Value>)
  • Sets and frozensets (Rust HashSet<Value>)
  • Dictionaries (Rust HashMap<Value, Value>)

When deserializing, arbitrary Python objects saved using a pickled instance dictionary or __setstate__ are replaced by that state, since version 0.5 of this library.

Note on enums: Enum variants are serialized as Python tuples (name, [data]) instead of mappings (or a plain string for unit variants), which is the representation selected by e.g. serde_json. On deserialization, both the tuple form and the string/mapping form is accepted.

Note on bytes objects: when deserializing bytes objects, you have to use a Rust wrapper type that enables deserialization from the serde data model’s “bytes” type. The serde_bytes crate provides such wrappers.

Likewise, Vec<u8>, [u8; N] and &[u8] are treated as sequences when serializing. This means that they will be serialized as a tuple or list of integers unless you use one of the wrappers in serde_bytes.

Unsupported features

  • Out-of-band data as introduced in Pickle protocol 5.

Exported API

The library exports generic serde (de)serializing functions to_* and from_*. It also exports functions that produce or take only the specific Value struct exposed by this library, which supports all built-in Python types (notably, long integers and sets, which serde’s generic types don’t handle). These functions, called value_from_* and value_to_*, will correctly (un)pickle these types.

Minimum Supported Rust Version

The minimum supported version of the toolchain is 1.41.1.



  • Pickle deserialization
  • Error objects and codes
  • Pickle serialization
  • Python values, and serialization instances for them.