Work item for entity lifecycle hooks

[SidShetye]

This is a work-item issue emerging from the parent discussion issue which already captures the community demand/severity. We'd like to regain functionality that existed in EF 6 but has been missing in EF Core.

EF Core should have the following events

1. ObjectMaterialized: An event fired when the raw data read from the database is filled into the entity object. As seen in EF 6 here.
2. SavingChanges: An event fired when the entity object is just about to be written to the database. As seen in EF 6 here.
3. SavedChanges: An event fired after the SavingChanges operation has completed (successfully or otherwise)

[weitzhandler]

Would it be better to replace the events with virtual methods, such as OnObjectMaterialized<TEntity>(TEntity entity) where TEntity : class etc?

[SidShetye]

@weitzhandler: Not really. See this for reasons

[ajcvickers]

Split out into separate issues #15910 and #15911 as requested by @divega on #626

[JValck]

For those who came here via SEO: because I needed this functionality myself, I created my own package with lifecycle hooks.

You can download it via NuGet. Full docs are available on the Github page of the project.