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Build URL

Zero-dependency Python snippets for building URLs using the standard library.

6 snippets available in this sub-category.

Simple

Build URL from components

url build components urlunparse web

Build URL from components

from urllib.parse import urlunparse

def build_url(scheme, netloc, path, params='', query='', fragment=''):
    """Build a URL from its components."""
    return urlunparse((scheme, netloc, path, params, query, fragment))

# Example usage
url = build_url('https', 'example.com', '/search', '', 'q=python', 'section')
print(url)  # https://example.com/search?q=python#section

Notes

  • urlunparse takes a 6-tuple: (scheme, netloc, path, params, query, fragment)
  • Use empty strings for missing parts

Add or replace query parameters in URL

url build query params web

Add or replace query parameters in URL

from urllib.parse import urlparse, parse_qs, urlencode, urlunparse

def add_query_params(url, params):
    """Add or replace query parameters in a URL."""
    parsed = urlparse(url)
    query = parse_qs(parsed.query)
    query.update(params)
    new_query = urlencode(query, doseq=True)
    return urlunparse(parsed._replace(query=new_query))

# Example usage
url = "https://example.com/search?q=python"
new_url = add_query_params(url, {"lang": "en", "q": "ai"})
print(new_url)  # https://example.com/search?q=ai&lang=en

Notes

  • doseq=True allows multiple values per key
  • Existing parameters are replaced if keys match

Join base and relative URLs

url build join base relative web

Join base and relative URLs

from urllib.parse import urljoin

base = "https://example.com/docs/"
relative = "../about/contact.html"
full_url = urljoin(base, relative)
print(full_url)  # https://example.com/about/contact.html

Notes

  • urljoin resolves relative paths against a base URL
  • Handles .., ., and missing slashes

Complex

Build URL with user, password, and port

url build user password port ftp web

Build URL with user, password, and port

from urllib.parse import urlunparse

def build_url_with_auth(scheme, user, password, host, port, path):
    """Build a URL with user, password, and port."""
    netloc = f"{user}:{password}@{host}:{port}" if user and password else f"{host}:{port}"
    return urlunparse((scheme, netloc, path, '', '', ''))

# Example usage
url = build_url_with_auth('ftp', 'user', 'pass', 'ftp.example.com', 2121, '/files')
print(url)  # ftp://user:pass@ftp.example.com:2121/files

Notes

  • Useful for FTP, SFTP, and authenticated endpoints

Build URL with fragment and params

url build fragment params web

Build URL with fragment and params

from urllib.parse import urlunparse

url = urlunparse(('https', 'example.com', '/page', '', '', 'section2'))
print(url)  # https://example.com/page#section2

url2 = urlunparse(('http', 'example.com', '/api', 'action', '', ''))
print(url2)  # http://example.com/api;action

Notes

  • Fragments follow #, params follow ; in the path

Edge Cases

Build URL with missing parts and double slashes

url build edge-case missing double-slash web

Build URL with missing parts and double slashes

from urllib.parse import urlunparse

# Missing netloc (relative URL)
url = urlunparse(('https', '', '/about', '', '', ''))
print(url)  # https:///about

# Double slashes in path
url2 = urlunparse(('https', 'example.com', '//double/slash', '', '', ''))
print(url2)  # https://example.com//double/slash

Notes

  • urlunparse does not normalize double slashes in path
  • Missing netloc results in scheme:///path

🔗 Cross-References

🏷️ Tags

url, build, join, query, params, fragment, edge-case, web, ftp

📝 Notes

  • Use urlunparse and urljoin for robust URL building
  • Always validate and encode user input in URLs
  • For more advanced manipulation, see urllib.parse docs