Comic Strip Downloader

Project writen in .NET 5

Proposal

Experimental project to show you:

• How to use the Type-Safe Enum Pattern in c#
• How to use the HtmlAgilityPack library to scrape a content for a web page (in this case a picture)

Parts of the project

ComicStripDownloader class library

IComicStripService

Interface with two methods

Task<ComicStripResponse> GetComicStripUrlAsync(DateTime, ComicStripType)

To get the Url of a Comic Strip

DateTime indicates the year, month and day of the Comic Strip

ComicStripType indicates the Comic Strip that we want to get

Task<ComicStripResponse> GetLastComicStripUrlAsync(ComicStripType)

To get the last Comic Strip

ComicStripType indicates the Comic Strip that we want to get

ComicStripResponse

Record object of the response returned by the service

string Source contains the result if the process has been executed correctly

bool HasErrors indicates if any error has been detected

string ErrorDescription contains details about the error if has been detected

ComicStripType

Use of the Type-Safe Enum Pattern to have all the details needed about a Comic Strip, that will be used by the service to get the Url of the Comic Strip correctly

The use of this pattern avoid possible problems when we are programming with Enum value type

There are two interesting static methods inside of this object

IReadOnlyCollection<ComicStripType> GetAll()

Get the list of all Comic Strip's. Each item, can be used as parameter to call to the service and get the Comic Strip Url

The values received in the collection are:

string Name of the Comic Strip

string Key for the Comic Strip

string Url used internally to get the Comic Strip

string Parameter used internally to prepare the Url of the Comic Strip

string HtmlImageClass used internally to get the Url of the Comic Strip using HtmlAgilityPack

string IsInChildNodes used internally to define if the Url is in a child node or not, and that will be used using HtmlAgilityPack

ComicStripType FindBy(string key)

Find the Comic Strip details for a Comic Strip Key

ComicStripService

Implementation of IComicStripService

How to use this project

A demo sample has been included in the code to show you how to use this library.

To get the last Comic Strip of Dilbert, you would write something like:

var response = await service.GetLastComicStripUrlAsync(ComicStripType.Dilbert);

And to get the Comic Strip of Dilbert for the 2020/09/25, you would write something like:

var response = await service.GetComicStripUrlAsync(new DateTime(2020, 9, 25), ComicStripType.Dilbert);

After this, response has the result of this task.

You should check if response.HasErrors is true or false.

If is false, you can get the Url in response.Source.

If is true, you can get the Error Details.

if (response.HasErrors)
    Console.WriteLine($"Error: {response.ErrorDescription}");
else
    Console.WriteLine($"Comic Strip Url: {response.Source}");

Comic Strips that you can download

• Andy Capp
• Back to B.C.
• B.C.
• Big Nate
• Big Nate: First Class
• Broom Hilda
• Calvin and Hobbes
• Cathy Classics
• Cul de Sac
• Dilbert
• Dilbert Classics
• Doonesbury
• Eyebeam Classics
• For Better or For Worse
• FoxTrot Classics
• Frank and Ernest
• Frazz
• Free Range
• Gardfield
• Gardfield Classics
• Geech
• Get Fuzzy
• Heart of the City
• Herman
• Luann
• Luann Againn
• Mutt and Jeff
• Nancy Classics
• Non Sequitur
• Peanuts
• Peanuts Begins
• Pearls Before Swine
• Phoebe and Her Unicorn
• Pickles
• Ruby Park
• Shirley and Son Classics
• Skippy
• Stone Soup Classics
• Tarzan
• The Knight Life
• Wallace the Brave
• Wizard of Id
• Wizard of Id Classics
• Ziggy