Lesson 24

Working with configuration files

Objective
By the end of this lesson, students will understand how to read and write configuration files in Python, specifically focusing on formats like '.ini' and '.json'. They will learn how to manage application settings and preferences efficiently.

1. Introduction to configuration files:

Configuration files are used to store settings and options for applications. They enable users to customize application behavior without modifying the source code.
Common formats for configuration files include '.ini', '.json', and '.yaml'.

2. Importance of configuration files:

Allow separation of code and configuration, making applications easier to maintain and configure.
- Facilitate user customization and preferences.
- Simplify deployment and management of application settings.

3. Working with INI files:

Introduce the configparser module for reading and writing .ini files.

Example: Reading from an INI file

import configparser

def read_ini_file(filename):
    config = configparser.ConfigParser()
    config.read(filename)
    return config

config = read_ini_file('config.ini')
print(config['Settings']['theme'])  # Output: dark

Example: Writing to an INI file

def write_ini_file(filename, config_data):
    config = configparser.ConfigParser()
    config.read_dict(config_data)
    with open(filename, 'w') as configfile:
        config.write(configfile)

config_data = {
    'Settings': {
        'theme': 'dark',
        'language': 'en'
    }
}
write_ini_file('config.ini', config_data)

4. Working with JSON configuration files:

Discuss the advantages of using JSON format for configuration files and how to utilize the json module.

Example: Reading from a JSON file

import json

def read_json_file(filename):
    with open(filename, 'r') as jsonfile:
        return json.load(jsonfile)

config = read_json_file('config.json')
print(config['theme'])  # Output: dark

Example: Writing to a JSON file

def write_json_file(filename, config_data):
    with open(filename, 'w') as jsonfile:
        json.dump(config_data, jsonfile, indent=4)

config_data = {
    'theme': 'dark',
    'language': 'en'
}
write_json_file('config.json', config_data)

5. Best Practices for working with configuration files:

Use a consistent format across applications to simplify maintenance.
Validate configuration data to ensure it meets application requirements.
Provide default configuration options in the application code.
Use comments in configuration files (for INI files) to clarify settings.

6. Exercises:

Exercise 1: Create and read an INI file
1. Write a program to create an INI configuration file with settings for a game (e.g., difficulty, volume) and read it back.

Exercise 2: Modify JSON Configuration
1. Implement a function that reads a JSON configuration file, modifies a setting (e.g., change the theme), and writes it back to the file.

Exercise 3: Validation of configuration Data
1. Write a program that reads a configuration file (INI or JSON) and validates that required settings are present and correctly formatted.

Exercise 4: Default configuration settings
1. Create a Python script that checks for the existence of a configuration file and loads default settings if the file is not found.

Conclusion
In this lesson, students learned about working with configuration files in Python, specifically focusing on reading and writing '.ini' and '.json' formats. Understanding how to manage configuration effectively is essential for building flexible and user-friendly applications.

import configparser def read_ini_file(filename): config = configparser.ConfigParser() config.read(filename) return config config = read_ini_file('config.ini') print(config['Settings']['theme']) # Output: dark

def write_ini_file(filename, config_data): config = configparser.ConfigParser() config.read_dict(config_data) with open(filename, 'w') as configfile: config.write(configfile) config_data = { 'Settings': { 'theme': 'dark', 'language': 'en' } } write_ini_file('config.ini', config_data)

def write_json_file(filename, config_data): with open(filename, 'w') as jsonfile: json.dump(config_data, jsonfile, indent=4) config_data = { 'theme': 'dark', 'language': 'en' } write_json_file('config.json', config_data)

File Handling in Python

Working with configuration files

File Handling in Python

Working with configuration files

File Handling in Python applications

Types of Files: Text vs. Binary

Opening and closing files

Working with file paths

Reading a whole file

Iterating through a file

Handling large files

Writing data to a file

Appending data to a file

Writing data in binary format

Working with CSV files

Working with JSON files

Pickling and unpickling objects

Checking for file existence

Renaming and deleting files

Working with directories

Common file handling exceptions

Using try-except blocks for safe file handling

Random access to files

Handling large data files with memory mapping

File compression

Log file management

Data persistence

Working with configuration files

Mini-Project: File management system