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PyJeb

PyJeb is a lightweight Python library to validate and variabilize configuration files.

It lets you define a control schema describing the expected structure of any YAML or JSON configuration, then applies it to validate values, inject defaults, and resolve variables — all in one call.

Features

• Validate configuration structure: required fields, types, format, allowed values
• Set default values for optional fields
• Inject dynamic values: system variables, user variables, custom functions
• Case-insensitive parameter matching
• Expose configuration as an attribute-accessible Python object

Installation

pip install pyjeb

How it works

1. Write your configuration file (YAML or JSON)
2. Define a control list describing expected fields
3. Call control_and_setup

Quick Example

The following example validates and enriches data ingestion job configurations loaded from a YAML file.

import yaml
from pyjeb import control_and_setup

with open("job.yaml") as f:
    config = yaml.safe_load(f)

controls = [
    { "name": "source", "type": "dict" },
    { "name": "source.path" },
    { "name": "source.format", "validset": ["csv", "json", "parquet"] },
    { "name": "source.pattern", "default": "*" },
    { "name": "target", "type": "dict" },
    { "name": "target.path" },
    { "name": "target.mode", "default": "append", "validset": ["append", "overwrite"] },
    { "name": "enabled", "type": "boolean", "default": True },
    { "name": "max_retries", "type": "integer", "default": 3 },
    { "name": "threshold", "type": "decimal", "default": 0.95 },
    { "name": "tags", "type": "list", "default": [] },
]

variables = { "env": "prod" }

for job_name, job_config in config.items():
    job = control_and_setup(job_config, controls, variables=variables, to_object=True)
    print(f"{job_name}: {job.source.path}")

Documentation

Page	Description
Getting Started	Step-by-step guide with a full working example
control_and_setup	API reference for the main function
Controls — Overview	All control fields and their purpose
Controls — Types	Supported types and type casting
Controls — Validset	Restrict values to an allowed set
Controls — Regex	Validate values against a regular expression
Controls — Expressions	Conditional value mapping with expressions
Controls — Conditional Controls	Dynamic control rules with if blocks
Variables — Overview	Introduction to the variable system
Variables — System	Built-in $sys.timestamp and $sys.date
Variables — User	Custom $var.<name> variables
Variables — Functions	Custom $func.<name> functions
Exceptions	Error types and when they are raised