Skip to content
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
47 lines (40 sloc) 2.09 KB
// Copyright (c) 2019 Jon P Smith, GitHub: JonPSmith, web:
// Licensed under MIT license. See License file in the project root for license information.
using System;
using System.Linq;
using DataLayerEvents.EfClasses;
using Microsoft.EntityFrameworkCore;
using StatusGeneric;
namespace Infrastructure.ConcurrencyHandlers
public static class BookWithEventsConcurrencyHandler
public static IStatusGeneric HandleCacheValuesConcurrency(this Exception ex, DbContext context)
var dbUpdateEx = ex as DbUpdateConcurrencyException;
if (dbUpdateEx == null)
return null; //can't handle this error
var status = new StatusGenericHandler();
//There could be multiple books if there was a bulk upload. Unusual, but best to handle it.
foreach (var entry in dbUpdateEx.Entries)
if (!(entry.Entity is BookWithEvents bookBeingWrittenOut))
return null; //This handler only handles BookWithEvents
//we read in the book that caused the concurrency issue
//This MUST be read as NoTracking otherwise it will interfere with the same entity we are trying to write
var bookThatCausedConcurrency = context.Set<BookWithEvents>().AsNoTracking()
.SingleOrDefault(p => p.BookId == bookBeingWrittenOut.BookId);
if (bookThatCausedConcurrency == null)
//The book was deleted so we need to stop the book being written out
entry.State = EntityState.Detached;
var handler = new FixConcurrencyMethods(entry, context);
handler.CheckFixReviewCacheValues(bookThatCausedConcurrency, bookBeingWrittenOut);
handler.CheckFixAuthorOrdered(bookThatCausedConcurrency, bookBeingWrittenOut);
return status; //We return a status with no errors, which tells the caller to retry the SaveChanges
You can’t perform that action at this time.