54 lines
2.2 KiB
C#
54 lines
2.2 KiB
C#
using System;
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using System.Threading.Tasks;
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using DataLayer;
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using Dinah.Core.ErrorHandling;
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namespace ScrapingDomainServices
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{
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public static class IProcessableExt
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{
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//
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// DO NOT USE ConfigureAwait(false) WITH ProcessAsync() unless ensuring ProcessAsync() implementation is cross-thread compatible
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// - ValidateAsync() doesn't need UI context. however, each class already uses ConfigureAwait(false)
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// - ProcessAsync() often does a lot with forms in the UI context
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//
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/// <summary>Process the first valid product. Create default context</summary>
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/// <returns>Returns either the status handler from the process, or null if all books have been processed</returns>
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public static async Task<StatusHandler> ProcessFirstValidAsync(this IProcessable processable)
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{
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var libraryBook = await processable.GetNextValidAsync();
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if (libraryBook == null)
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return null;
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var status = await processable.ProcessAsync(libraryBook);
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if (status == null)
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throw new Exception("Processable should never return a null status");
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return status;
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}
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// i'd love to turn this into Task<IEnumerable<LibraryBook>>
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// since enumeration is a blocking operation, this won't be possible until
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// 2019's C# 8 async streams, aka async enumerables, aka async iterators: https://blogs.msdn.microsoft.com/dotnet/2018/11/12/building-c-8-0/
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public static async Task<LibraryBook> GetNextValidAsync(this IProcessable processable)
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{
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var libraryBooks = LibraryQueries.GetLibrary_Flat_NoTracking();
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foreach (var libraryBook in libraryBooks)
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if (await processable.ValidateAsync(libraryBook))
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return libraryBook;
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return null;
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}
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public static async Task<StatusHandler> ProcessValidateLibraryBookAsync(this IProcessable processable, LibraryBook libraryBook)
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{
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if (!await processable.ValidateAsync(libraryBook))
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return new StatusHandler { "Validation failed" };
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return await processable.ProcessAsync(libraryBook);
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}
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}
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}
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