Application Urls

• Basic Usage
  • Creating an AppUrl
  • Using AppUrls
  • Parsing Strings
  • The URL Base Class
• File Urls
• Web Urls
• Archive Urls
• Resolving and Extending Urls

Application Urls provide structure and operations on URLS where the file the URL refers to can’t, in general, simply be downloaded. For instance, you may want to refer to a CSV file inside a ZIP archive, or a worksheet in an Excel file. In conjunction with Row Generators, Application Urls are often used to refer to tabular data stored on data repositories. For instance:

• Stored on the web: http://examples.com/file.csv
• Inside a zip file on the web: http://example.com/archive.zip#file.csv
• A worksheet in an Excel file: http://example.com/excel.xls#worksheet
• A worksheet in an Excel file in a ZIP Archive: http://example.com/archive.zip#excel.xls;worksheet
• An API: socrata+http://chhs.data.ca.gov/api/views/tthg-z4mf

The module defines an entry_point, so other modules can extend the types of URLs can that can produced by parse_app_url(). For instance, the pandas-reporter module extends appurl to access Census tables from Census Reporter, using URLs such as censusreporter:B17001/140/05000US06073

Typical use – for downloading an archive and extracting a file from it – is:

from appurl import  parse_app_url
from os.path import exists

url = parse_app_url("http://example.com/archive.zip#file.csv")

resource_url = url.get_resource() # Download the .zip file

target_path = resource_url.get_target() # Extract `file.csv` from the .zip

assert(exists(target_path)) # The path to file.csv