Utilities

Configr includes utility functions that support the configuration management functionality. This page documents the core utility functions available in Configr.

to_snake_case

def to_snake_case(name: str) -> str:
    """
    Convert name to snake case, special chars are replaced with _
    and numbers are kept.
    """

The to_snake_case function converts a string in camelCase, PascalCase, or other formats to snake_case.

Parameters

Parameter	Type	Description
name	str	The string to convert to snake_case format

Returns

A string converted to snake_case format.

Examples

from configr.utils import to_snake_case

# Converting PascalCase
result = to_snake_case("DatabaseConfig")
print(result)  # "database_config"

# Converting camelCase
result = to_snake_case("databaseConfig")
print(result)  # "database_config"

# With numbers
result = to_snake_case("API123Config")
print(result)  # "api123_config"

# With acronyms
result = to_snake_case("DBConfig")
print(result)  # "db_config"

# With mixed case
result = to_snake_case("JSONAPIConfig")
print(result)  # "json_api_config"

Implementation Details

The function:

1. If the input is a simple lowercase word without special characters, returns it as is
2. Otherwise, uses regular expressions to find:
   • Lowercase letters and numbers together
   • Uppercase letters, optionally followed by uppercase letters, numbers, or lowercase letters
3. Joins these elements with underscores
4. Converts everything to lowercase

The core regular expression pattern is:

re.findall(r'[a-z0-9]+|[A-Z](?:[A-Z0-9]*(?![a-z])|[a-z0-9]*)', name)

This pattern matches:

• Groups of lowercase letters and numbers: [a-z0-9]+

OR

• An uppercase letter: [A-Z] followed by either:
  • Zero or more uppercase letters and numbers not followed by a lowercase letter: [A-Z0-9]*(?![a-z])

OR

- Zero or more lowercase letters and numbers: `[a-z0-9]*`

Usage in Configr

The to_snake_case function is used internally by Configr in the config_class decorator to derive default configuration file names from class names when a specific file name is not provided.

For example, a class named DatabaseConfig would, by default, look for a configuration file named database_config ( with any supported extension like .json or .yaml).

@config_class  # Will use database_config as the base name
class DatabaseConfig:
    host: str
    port: int

This helps maintain a consistent naming convention for configuration files that follows Python's standard style guidelines.