Delta migration improvements

[twozero6]

Motivation

We are currently using the Kentico Migration Toolkit to perform migrations from a large legacy Kentico sites to XbyK. It would help us managing delta migrations if the tool would allow us to control what items are migrated during subsequent delta (incremental) runs. This would allow us to do delta imports on stable, high-volume content like blogs, events, downloads, and articles, without having to reimport everything. We would be able to give the customer responsibility for maintaining all highly, configured pages (e.g., landing pages), while helping them migrate the latest simple, structured pages before a launch.

Proposed solution

We're imagining that the existing extension framework (e.g., custom class mapping) could allow adding something like a "ShouldMigrate" action that is called to check if a content item should be migrated. This would allow us to implement any rules we need, whether it's based on site section, last modified date, or even data integrity checks. Examples of data integrity checks could be, checking if an asset file exists, or checking if a parent object exists in the target.

Specifically, we would like the ability to introduce custom logic that determines whether a given content item should be included or excluded in the migration on a per-item basis.

Secondary ideas

Here's some other things that would help

Logging items that were skipped either due to the ShouldMigrate result or app_settings exclusions.

Logging warnings instead of crashing with an exception if an item could not be migrated due to a missing parent or other data integrity problem.

Additional context

We're planning how to handle delta migrations with a current customer, it would be a huge win if we could tell them that Kentico is updating the tool to support the needs. It would prevent creating a custom tool (something we are considering) or asking them to do months of dual content entry.

It would also make delta migrations less scary. Would would have less challenges trying to merge changes through CI and have less worry about corrupting the database.

We appreciate your consideration of these enhancements. Thank you for your time and ongoing support!