In this week’s newsletter, I want to introduce you to the concept of auditable entities and how you can implement it with Entity Framework Core.

For starters, Auditable Entities is a best practice applied on each entity to track changes applied on it. These are nothing but meta columns apart from the attributes, which store information about when the entity was created, updated and the user who did it etc.

Maintaining such information helps us keep trail of how these entities have changed over time.

However, manually inserting or updating these fields can be painful, as there can be a chance of human error.

To automate this process, we can design a system with which we can automatically store such information without having to manually inserting any such value.

How do we do that?

EF Core exposes a property ChangeTracker which "Provides access to information and operations for entity instances this context is tracking".

When we call ChangeTracker.Entities<TClass>() with a type parameter, it returns all the entities currently tracked which are of the type passed.

In our case, we passed AuditableEntity which results in all entities which are of type AuditableEntity.

Remember that Item extends AuditableEntity so it qualifies the "is-a" relationship.

So we get all the Item objects. Since User extends BaseEntity and NOT AuditableEntity, User is not a AuditableEntity and so those entities are not returned. Simple!

Within the loop, we see if the record is being added or updated based on the State - EntityState.Added or EntityState.Modified. If it is INSERT we set values for Created and CreatedBy. If UPDATE we set values of LastModified and ModifiedBy.

I have explained this in much detail with an illustrating example. The link to the article is here - https://referbruv.com/blog/how-to-setup-audit-fields-using-ef-core/

I hope this article will help you get a better understanding of the concept and help you know something new.

I’ll see you next week!