Possible mistakes in Connection Resiliency example

[stevendarby]

In the section "Option 3 - Add state verification", the code block uses verifySucceeded to check if a Blog exists with aBlogId equal to blogToAdd.BlogId. Due to acceptAllChangesOnSuccess being set to false, I believe the store-generated blogToAdd.BlogId will still be 0 at this point and this check will always fail, or at least will be the wrong check to make. There could be a few ways to improve the example but one might be to use db.Entry(blogToAdd).CurrentValues[nameof(Blog.BlogId)] as I think this will have the store-generated value in it.

Also, if my understanding is correct, AsNoTracking() is redundant here as no entity is returned by the query. Would it be best to remove this, not just for brevity but so as to avoid any confusion about its function?

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Document Details

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• ID: 876c88d4-2972-d905-28d7-56f9e589f309
• Version Independent ID: 29002343-fa42-2f49-3362-53592039b26d
• Content: Connection Resiliency - EF Core
• Content Source: entity-framework/core/miscellaneous/connection-resiliency.md
• Product: entity-framework
• Technology: entity-framework-core
• GitHub Login: @AndriySvyryd
• Microsoft Alias: avickers

[stevendarby]

While on the topic, is there any mechanism by which I can simulate a transient error during a commit to see verifySucceeded in action, to check it's working as expected? With reflection I'm able to build a transient error exception, which I can thrown in place of calls to SaveChanges to ensure my code works as expected on a retry, but the commit scenario seems difficult.

This is one reason why I think it could be worth reworking the example in your documentation - some may have copied the approach and been unable to truly test it themselves, leaving them open to a (very small!) chance of data corruption.

[ajcvickers]

@stevendarby It does look like something is amiss here. We will take a look, and potentially also add a sample that causes this code to execute, like you suggest. You might also want to take a look at some of the tests we have for this. For example, https://github.com/dotnet/efcore/blob/main/test/EFCore.SqlServer.FunctionalTests/ExecutionStrategyTest.cs#L37