Unserializing

Unserializing is the process of converting serialized data back into a usable data structure or object in memory. It is the counterpart of serialization.

During unserialization, a program reads a stream or string that encodes data, parses it according to a format, and reconstructs primitive types, arrays, and, when allowed by the environment, class instances. The result may preserve object graphs and references, depending on the serializer.

Common formats for serialized data include JSON, XML, YAML, and binary schemes such as Protocol Buffers or MessagePack. Many languages provide built-in or library-based functions or methods to unserialize data, sometimes with variations on how type information and object identity are handled.

Security and reliability considerations are central. Unserializing data from untrusted sources can lead to vulnerabilities such as object injection or code execution in certain environments. It can also fail if the serialized form does not match the expected schema or version.

Best practices include validating or sandboxing input, avoiding deserialization of untrusted data when possible, preferring text-based formats like JSON with explicit schemas, and using explicit constructors or factories to reconstruct objects rather than directly instantiating arbitrary classes.