Python Rison Encoder/Decoder

Common errors

• ModuleNotFoundError: No module named 'prison'

  cause The 'prison' library is not installed in the Python environment where the code is being executed.
  fix pip install prison

• prison.decoder.ParserException: missing ', '

  cause The input string provided to `prison.loads()` is not valid Rison, often due to improper escaping of special characters or malformed Rison syntax.
  fix Ensure the Rison string conforms to the Rison specification. If constructing the string manually, be mindful of characters like '!', '(', ')', ':', and ',' and use `prison.dumps()` to serialize Python objects into valid Rison. For example, `prison.loads("(key:value)")` for an object, or `prison.loads("!(item1,item2)")` for an array.

• rison decoder error: missing ':'

  cause The input Rison string is syntactically incorrect, specifically missing a colon where a key-value pair is expected in an object, or other structural issues.
  fix Verify that your Rison string adheres to the correct syntax. For object keys, ensure they are followed by a colon and a value, e.g., `(key:value)`. Use `prison.dumps()` to reliably generate correct Rison strings.

• AttributeError: module 'prison' has no attribute 'dumps'

  cause This error occurs when attempting to access a function or attribute, such as `dumps` or `loads`, from the 'prison' module incorrectly, often by trying to import them directly when they are intended to be accessed as methods of the imported module itself.
  fix Import the 'prison' module and access its functions as attributes, e.g., `import prison` then `prison.dumps()` or `prison.loads()`.

Warnings

• gotcha Rison is not JSON. Its syntax and supported data types differ significantly. Direct mental mapping from JSON to Rison often leads to parsing errors or unexpected output. For example, objects use parentheses `()` instead of curly braces `{}`, and unquoted identifiers are common.
  Fix: Familiarize yourself with the Rison specification, especially regarding object and array delimiters, string quoting rules, and special values like `!n` for null.
• gotcha The `prison` library has not been updated since August 2021 (v0.2.1). While stable and functional for the existing Rison specification, new Python features, performance optimizations, or edge-case bug fixes are unlikely to be implemented.
  Fix: Be aware that the library's development is quiescent. For mission-critical applications, consider a review of its source code or potential maintenance forks if advanced features or active support become necessary.
• gotcha Deserializing Rison data from untrusted sources with `prison.loads()` carries inherent security risks. While Rison's simplicity mitigates some complex attack vectors found in formats like YAML or Pickle, malicious input could still lead to resource exhaustion (e.g., deep nesting) or unexpected data structures.
  Fix: Always validate or sanitize Rison input from untrusted sources. Limit the depth of nested structures and verify data types if parsing user-supplied data.

Install

• pip install prison Install latest version

Imports

• loads

  from prison import loads

• dumps

  from prison import dumps

Quickstart

Demonstrates encoding a Python dictionary to a Rison string and then decoding it back. Rison is optimized for URL-safe representation of simple data structures.

import prison

data = {'name': 'Alice', 'age': 30, 'tags': ['dev', 'python']}

# Encode Python dict to Rison string
rison_string = prison.dumps(data)
print(f"Encoded Rison: {rison_string}")
# Expected: (name:Alice,age:30,tags:!(dev,python))

# Decode Rison string back to Python dict
decoded_data = prison.loads(rison_string)
print(f"Decoded data: {decoded_data}")
# Expected: {'name': 'Alice', 'age': 30, 'tags': ['dev', 'python']}