Course Topics
Python Basics Introduction and Setup Syntax and Indentation Comments and Documentation Running Python Programs Exercise Variables and Data Types Variables and Assignment Numbers (int, float, complex) Strings and Operations Booleans and None Type Conversion Exercise Operators Arithmetic Operators Comparison Operators Logical Operators Assignment Operators Bitwise Operators Exercise Input and Output Getting User Input Formatting Output Print Function Features Exercise Control Flow - Conditionals If Statements If-Else Statements Elif Statements Nested Conditionals Exercise Control Flow - Loops For Loops While Loops Loop Control (break, continue) Nested Loops Exercise Data Structures - Lists Creating and Accessing Lists List Methods and Operations List Slicing List Comprehensions Exercise Data Structures - Tuples Creating and Accessing Tuples Tuple Methods and Operations Tuple Packing and Unpacking Exercise Data Structures - Dictionaries Creating and Accessing Dictionaries Dictionary Methods and Operations Dictionary Comprehensions Exercise Data Structures - Sets Creating and Accessing Sets Set Methods and Operations Set Comprehensions Exercise Functions Defining Functions Function Parameters and Arguments Return Statements Scope and Variables Lambda Functions Exercise String Manipulation String Indexing and Slicing String Methods String Formatting Regular Expressions Basics Exercise File Handling Opening and Closing Files Reading from Files Writing to Files File Modes and Context Managers Exercise Error Handling Understanding Exceptions Try-Except Blocks Finally and Else Clauses Raising Custom Exceptions Exercise Object-Oriented Programming - Classes Introduction to OOP Creating Classes and Objects Instance Variables and Methods Constructor Method Exercise Object-Oriented Programming - Advanced Inheritance Method Overriding Class Variables and Methods Static Methods Exercise Modules and Packages Importing Modules Creating Custom Modules Python Standard Library Installing External Packages Exercise Working with APIs and JSON Making HTTP Requests JSON Data Handling Working with REST APIs Exercise Database Basics Introduction to Databases SQLite with Python CRUD Operations Exercise Final Project Project Planning Building Complete Application Code Organization Testing and Debugging Exercise

Making HTTP Requests

Introduction

Why this topic matters: Understanding how to make HTTP requests is essential in developing web applications and interacting with APIs (Application Programming Interfaces). It allows your programs to communicate with various web services, fetch data, and even manipulate it.

What you'll learn: In this lesson, we will explore the fundamentals of making HTTP requests using Python, including popular libraries such as requests and aiohttp. You will gain practical experience in sending GET, POST, PUT, DELETE, and other types of requests to retrieve and modify data.

Core Concepts

Main explanation with examples: The Hypertext Transfer Protocol (HTTP) is a protocol used for transmitting hypertext between servers and clients on the web. HTTP requests are messages sent by clients (like your Python script) to servers, asking them to perform certain actions.

In Python, we can use the requests library to make HTTP requests. Here's an example of sending a GET request:

import requests
response = requests.get('https://api.example.com/data')

Key terminology:
- HTTP methods: Methods used in HTTP requests, such as GET, POST, PUT, DELETE, etc., to perform various actions on resources.
- URL: The Uniform Resource Locator (URL) is the address of a resource on the web that clients use to request data from servers.
- Headers: Additional information sent along with HTTP requests, such as authentication credentials or content types.
- Body: Data payload sent in an HTTP request, typically used when creating resources (e.g., POST requests).

Practical Examples

Real-world code examples: Let's create a simple script that fetches data from the jsonplaceholder API and prints it out:

import requests

response = requests.get('https://jsonplaceholder.typicode.com/todos/1')
data = response.json()
print(data)

Step-by-step explanations:
1. Import the requests library.
2. Send a GET request to the specified URL (in this case, https://jsonplaceholder.typicode.com/todos/1).
3. Parse the response as JSON using the .json() method.
4. Print out the data.

Common Issues and Solutions (CRITICAL SECTION)

NameError

What causes it: This error occurs when you try to use an undefined variable in your code.

response = requests.get(todos_url)  # undefined variable todos_url

Error message:

NameError: name 'todos_url' is not defined

Solution: Define the variable before using it in your code.

todos_url = 'https://jsonplaceholder.typicode.com/todos/1'
response = requests.get(todos_url)

Why it happens: This error occurs when you try to use a variable that has not been defined yet in your code.

How to prevent it: Make sure to define all variables before using them in your code.

TypeError

What causes it: This error occurs when you pass an incorrect data type where another is expected, such as passing a string instead of an integer.

response = requests.get(todos_url, params={'id': '1'})  # passing a string for id parameter

Error message:

TypeError: int() argument must be a string, not 'str'

Solution: Ensure you pass the correct data type for your parameters.

response = requests.get(todos_url, params={'id': 1})

Why it happens: This error occurs when you try to convert a string to an integer (or vice versa) where another data type is expected.

How to prevent it: Be mindful of the data types you are using and ensure they match the requirements for your specific use case.

** requests.exceptions.RequestException**

What causes it: This exception occurs when an unexpected error happens during the request, such as a network issue or a server error.

response = requests.get(todos_url)

Error message:

requests.exceptions.RequestException: HTTPError: 500 Internal Server Error

Solution: Inspect the response object to determine the cause of the error and adjust your code accordingly.

response = requests.get(todos_url)
if response.status_code != 200:
    print(f"Error occurred with status code {response.status_code}")
else:
    data = response.json()
    print(data)

Why it happens: This error can occur due to various reasons, such as network connectivity issues, server errors, or incorrect API usage.

How to prevent it: Ensure your code is well-structured, and any potential errors are handled appropriately. Check the response status code before processing the data.

Best Practices

  • Use try-except blocks to handle exceptions gracefully and provide meaningful error messages.
  • Validate input data before sending requests to avoid passing incorrect data types or values.
  • Utilize libraries like aiohttp for asynchronous HTTP requests when dealing with multiple concurrent requests.
  • Always include relevant headers (e.g., Content-Type, Authorization) in your requests if necessary.

Key Takeaways

  • Understand the basics of making HTTP requests using Python and popular libraries like requests and aiohttp.
  • Familiarize yourself with common HTTP methods, URLs, headers, and bodies.
  • Learn how to handle errors gracefully and validate input data to prevent issues.
  • Follow best practices for structuring your code and optimizing performance when making HTTP requests.
  • Explore more advanced topics like asynchronous requests, rate limiting, and error handling in future learning endeavors.
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