Python Working with APIs

APIs let your program talk to other services. Most modern applications depend on APIs.

  In Python, the most common beginner-friendly library for HTTP is `requests`.
  
  ## Install requests
  
  ```bash
  pip install requests
  ```
  
  ## GET request (fetch data)
  
  ```python
  import requests
  
  response = requests.get("https://api.github.com/users/octocat", timeout=10)
  
  print("Status:", response.status_code)
  
  if response.status_code == 200:
      data = response.json()
      print("Login:", data.get("login"))
      print("Type:", data.get("type"))
  else:
      print("Request failed")
  ```
  
  Expected output example:
  
  ```
  Status: 200
  Login: octocat
  Type: User
  ```
  
  ## Query parameters
  
  ```python
  import requests
  
  params = {"q": "python", "sort": "stars"}
  response = requests.get("https://api.github.com/search/repositories", params=params, timeout=10)
  
  data = response.json()
  print("Total:", data.get("total_count"))
  ```
  
  ## POST request (send data)
  
  ```python
  import requests
  
  payload = {"name": "Tom", "email": "tom@example.com"}
  
  response = requests.post("https://httpbin.org/post", json=payload, timeout=10)
  data = response.json()
  
  print(data["json"])
  ```
  
  Expected output:
  
  ```
  {'name': 'Tom', 'email': 'tom@example.com'}
  ```
  
  ## Headers (authentication is usually here)
  
  ```python
  import requests
  
  headers = {
      "Authorization": "Bearer YOUR_TOKEN",
      "Content-Type": "application/json"
  }
  
  response = requests.get("https://api.example.com/data", headers=headers, timeout=10)
  ```
  
  ## Error handling (professional pattern)
  
  ```python
  import requests
  
  try:
      response = requests.get("https://api.github.com/users/octocat", timeout=5)
      response.raise_for_status()
      data = response.json()
      print(data.get("login"))
  except requests.exceptions.Timeout:
      print("Request timed out.")
  except requests.exceptions.HTTPError as e:
      print("HTTP error:", e)
  except requests.exceptions.RequestException as e:
      print("Request failed:", e)
  ```
  
  ## Graph: API request flow
  
  ```mermaid
  flowchart LR
    A[Client code] --> B[HTTP request]
    B --> C[Server API]
    C --> D[JSON response]
    D --> E[Parse with .json()]
    E --> F[Use data in app]
  ```
  
  In the next lesson, you will revisit list methods in a more complete way, including what each method returns and how to avoid common list bugs.