New Community Website

Ordinarily, you'd be at the right spot, but we've recently launched a brand new community website... For the community, by the community.

Yay... Take Me to the Community!

The Community Blog is a personal opinion of community members and by no means the official standpoint of DNN Corp or DNN Platform. This is a place to express personal thoughts about DNNPlatform, the community and its ecosystem. Do you have useful information that you would like to share with the DNN Community in a featured article or blog? If so, please contact .

The use of the Community Blog is covered by our Community Blog Guidelines - please read before commenting or posting.

DAL 2 - Controlling your Mappings

I presented a session on the DAL 2 at DNN World in Orlando, and a few people asked about “calculated” properties - or properties that do not have any matching column in the database.  This is an important feature for any “auto-mapped” repository implementation, so we have added three new Attributes that control the mapping of properties and columns.

IgnoreColumn Attribute

The first of the new attributes is the IgnoreColumn attribute.  Applying this attribute to a property will mean that the property is ignored when mapping the class to it’s corresponding Database table.  Continuing to use the Task class from previous blog posts, lets look at an updated version where there is a new property that shouldn’t be saved to the Database.

Listing 1: The Task class


The new “PropertyNotInDatabase” property does not have a corresponding column in the database, and this would throw an error.  This can be made to work by adding the new IgnoreColumn attribute - see Listing 2.

Listing 2: Aplying the IgnoreColumn Attribute


DeclareColumns and IncludeColumn Attribute

An alternative approach is to work the other way - i.e. require the class to specify columns that map to fields in the database.  This would be the preferred approach if the class has less “included” columns than “excluded” columns.  Or maybe as a developer you feel that your intentions are clearer by explicitly including columns to be mapped.

The DeclareColumns attribute can be applied at the class level, and if applied only properties that have the IncludeColumn attribute applied will be mapped to the database table - see Listing 3

Listing 3: Applying the DeclareColumns and IncludeColumns Attributes


So this concludes this introductory series of articles on the new DAL 2.  Please continue to send your feedback as you use it in your module development, so we can continue to improve it.

This blog is cross-posted from my personal blog.


Tim McCurdy
I get what you're trying to do, but why didn't you just add support for the Attributes which already exist under the DataAnnotations? This way, if I already had Entities designed using Entity Framework, they would just translate right over to DNN without (or with only minor) changes.

I've developed mappers which were much better than PetaPoco or EF, so I guess I just keep using my own.
* They map from DataReaders, DataTable etc into POCOs and back again.
* They map to/from Stored Procs to DbCommands (using the DB Metadata if I choose).
* They map to base class properties, and support nested objects.

Why are we still reinventing things like this in 2015?
Tim McCurdy Tuesday, May 5, 2015 2:49 PM (link)
Joseph Craig
For those trying to use this (and possibly other blog entries on DAL2) you should be aware that the square brackets ( [] ) should be replaced by angle brackets ( <> ).

I'm guessing that this changed between the writing of the blog and now ...
Joseph Craig Friday, April 20, 2018 8:08 PM (link)

Comment Form

Only registered users may post comments.


Aderson Oliveira (22)
Alec Whittington (11)
Alessandra Davies (3)
Alex Shirley (10)
Andrew Hoefling (3)
Andrew Nurse (30)
Andy Tryba (1)
Anthony Glenwright (5)
Antonio Chagoury (28)
Ash Prasad (37)
Ben Schmidt (1)
Benjamin Hermann (25)
Benoit Sarton (9)
Beth Firebaugh (12)
Bill Walker (36)
Bob Kruger (5)
Bogdan Litescu (1)
Brian Dukes (2)
Brice Snow (1)
Bruce Chapman (20)
Bryan Andrews (1)
cathal connolly (55)
Charles Nurse (163)
Chris Hammond (213)
Chris Paterra (55)
Clint Patterson (108)
Cuong Dang (21)
Daniel Bartholomew (2)
Daniel Mettler (181)
Daniel Valadas (48)
Dave Buckner (2)
David Poindexter (12)
David Rodriguez (3)
Dennis Shiao (1)
Doug Howell (11)
Erik van Ballegoij (30)
Ernst Peter Tamminga (80)
Francisco Perez Andres (17)
Geoff Barlow (12)
George Alatrash (12)
Gifford Watkins (3)
Gilles Le Pigocher (3)
Ian Robinson (7)
Israel Martinez (17)
Jan Blomquist (2)
Jan Jonas (3)
Jaspreet Bhatia (1)
Jenni Merrifield (6)
Joe Brinkman (274)
John Mitchell (1)
Jon Henning (14)
Jonathan Sheely (4)
Jordan Coopersmith (1)
Joseph Craig (2)
Kan Ma (1)
Keivan Beigi (3)
Kelly Ford (4)
Ken Grierson (10)
Kevin Schreiner (6)
Leigh Pointer (31)
Lorraine Young (60)
Malik Khan (1)
Matt Rutledge (2)
Matthias Schlomann (16)
Mauricio Márquez (5)
Michael Doxsey (7)
Michael Tobisch (3)
Michael Washington (202)
Miguel Gatmaytan (3)
Mike Horton (19)
Mitchel Sellers (40)
Nathan Rover (3)
Navin V Nagiah (14)
Néstor Sánchez (31)
Nik Kalyani (14)
Oliver Hine (1)
Patricio F. Salinas (1)
Patrick Ryan (1)
Peter Donker (54)
Philip Beadle (135)
Philipp Becker (4)
Richard Dumas (22)
Robert J Collins (5)
Roger Selwyn (8)
Ruben Lopez (1)
Ryan Martinez (1)
Sacha Trauwaen (1)
Salar Golestanian (4)
Sanjay Mehrotra (9)
Scott McCulloch (1)
Scott Schlesier (11)
Scott Wilkinson (3)
Scott Willhite (97)
Sebastian Leupold (80)
Shaun Walker (237)
Shawn Mehaffie (17)
Stefan Cullmann (12)
Stefan Kamphuis (12)
Steve Fabian (31)
Steven Fisher (1)
Tony Henrich (3)
Torsten Weggen (3)
Tycho de Waard (4)
Vicenç Masanas (27)
Vincent Nguyen (3)
Vitaly Kozadayev (6)
Will Morgenweck (40)
Will Strohl (180)
William Severance (5)
What is Liquid Content?
Find Out
What is Liquid Content?
Find Out
What is Liquid Content?
Find Out