Automatic audit fields

instead of setting the audit values manually on each and every save or update operation, you can take advantage of a DBContext instance where you will instantiate the context by providing it with the details of the current user performing the operations once, and then use the db context to perform all subsequesnt save/update operations so that all the audit fields will be set on the entities automatically.

Enable audit fields

simply add a property of type ModifiedBy to the entity class where you'd like to enable audit fields. The ModifiedBy type is provided by the library. It can be inherited and other properties can be added to it as you please.

public class Book : Entity
{
    public string Title { get; set; }
    public ModifiedBy ModifiedBy { get; set; }
}

Instantiate a DBContext

instantiate a context by providing it a ModifiedBy instance with the current user's details filled in.

var currentUser = new ModifiedBy
{
    UserID = "xxxxxxxxxxxx",
    UserName = "Kip Jennings"
};

var db = new DBContext(modifiedBy: currentUser);

Perform entity operations

in order for the auto audit fields to work, you must use the db context to perform the operations instead of the DB static methods like you'd typically use.

var book = new Book { Title = "test book" };

await db.SaveAsync(book);

await db.Update<Book>()
        .MatchID(book.ID)
        .Modify(b => b.Title, "updated title")
        .ExecuteAsync();

doing so will result in the following document in mongodb:

{
	"_id" : ObjectId("xxxxxxxxxxxx"),
	"Title" : "updated title", //this will initially be 'test book'
	"ModifiedBy" : {
		"UserID" : "xxxxxxxxxxxx",
		"UserName" : "Kip Jennings"
	}
}

Get/set audit values

it is also possible to instantiate a DBContext without supplying a ModifiedBy to the constructor and set or get it like so:

var dbContext = new DBContext();

db.ModifiedBy = new ModifiedBy
{
    UserID = "xxxxxxxxxxxx",
    UserName = "Kip Jennings"
};

var currentUser = db.ModifiedBy;

Transaction support

a transaction with audit field support can be performed with the DBContext like so:

var db = new DBContext(modifiedBy: currentUser);

using (db.Transaction())
{
    await db.SaveAsync(book);
    await db.CommitAsync();
}

or it can be performed with a Transaction instance like so:

using (var TN = DB.Transaction(modifiedBy: currentUser))
{
    await TN.SaveAsync(book);
    await TN.CommitAsync();
}

Note

please refer to the transactions page for a detailed explanation of how transactions work.