Clear member cache by older user name when member user name is updated (13)

[AndyButland]

Prerequisites

• I have added steps to test this contribution in the description below

Resolves #19618 for Umbraco 13

Description

The linked issue discusses the problem where updating a user in the backoffice to change the user name still leaves the member cached and retrievable by the old user name.

This PR uses the AdditionalData collection available on entities to provide the previous user name to the cache refresher, so it can clear by the old user name as well as the new.

I've also added a constant for the AdditionalData key and used it for one other instance.

Testing

With code like the following, retrieve a member by the user name:

@inject IMemberService MemberService;
@{
    var fred = MemberService.GetByUsername("fred@test.com");
    @if (fred is null)
    {
        <div>Fred not found</div>
    }
    else
    {
        <div>Found Fred: @fred.Email</div>
    }
}

Update the member's user name in the backoffice. Before the PR you will see the member is still found, but after these changes are applied, it should not be.

[Copilot]

Pull Request Overview

This PR ensures that when a member’s username is updated, any cached entries under the old username are also purged by capturing and propagating the previous username.

• Capture the old username in AdditionalData on member save
• Extend the cache refresher payload to include PreviousUsername and clear both old and new keys
• Introduce constants for the additional-data keys and update related handlers and extensions

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Umbraco.Core/Services/MemberService.cs	Capture previous username before save and populate AdditionalData
src/Umbraco.Core/Models/MemberGroup.cs	Replace literal "previousName" with a constant key
src/Umbraco.Core/Handlers/PublicAccessHandler.cs	Use constant key to detect and rename by previous member-group name
src/Umbraco.Core/Constants-Entities.cs	Define MemberPreviousUserName and MemberGroupPreviousName constants
src/Umbraco.Core/Cache/Refreshers/Implement/MemberCacheRefresher.cs	Add PreviousUsername to payload and clear cache by old name
src/Umbraco.Core/Cache/DistributedCacheExtensions.cs	Refactor to build payloads with PreviousUsername

Comments suppressed due to low confidence (1)

src/Umbraco.Core/Cache/DistributedCacheExtensions.cs:175

• Add unit tests for GetPayloads and the cache refresher to verify that PreviousUsername is correctly populated and that cache entries are cleared for both the old and new usernames.

    private static IEnumerable<MemberCacheRefresher.JsonPayload> GetPayloads(IEnumerable<IMember> members, bool removed)

[nikolajlauridsen]

LGTM 👍