How to Create a Many-to-Many Relationship (Andy Kung)

re: How to Create a Many-to-Many Relationship (Andy Kung)

HELP — Wed, 16 Jan 2013 22:56:02 GMT

Can this be done on a List and Details screen. I am have issue getting it to work. works fine on a New Data Screen

re: How to Create a Many-to-Many Relationship (Andy Kung)

lisnb — Fri, 16 Nov 2012 07:02:47 GMT

it's really helpful for me, thanks ~

and lightswitch is so powerful that i can't help getting to learn it.

re: How to Create a Many-to-Many Relationship (Andy Kung)

ITPSB — Mon, 26 Mar 2012 01:56:18 GMT

Actually best after:

MovieGenre mg = this.MovieGenres.AddNew();

mg.Movie = this.MovieProperty;

mg.Genre = this.Genres.SelectedItem

mgExists.Delete(); // Add this line to delete instance after test

re: How to Create a Many-to-Many Relationship (Andy Kung)

ITPSB — Mon, 26 Mar 2012 00:34:27 GMT

Just add this line to delete the test for the mgExits instanceafter the test is completed (see comment to the right of the added line below).

partial void AddGenre_Execute()

{

// Write your code here.

if (Genres.SelectedItem != null)

{

MovieGenre mgExists = new MovieGenre();

foreach (MovieGenre mgSearch in this.MovieGenres)

{

if (mgSearch.Genre.Name == this.Genres.SelectedItem.Name)

{

mgExists = mgSearch;

}

if (mgExists == null || mgExists.Genre == null)

{

mgExists.Delete(); // Add this line to delete instance after test

MovieGenre mg = this.MovieGenres.AddNew();

mg.Movie = this.MovieProperty;

mg.Genre = this.Genres.SelectedItem;

}

re: How to Create a Many-to-Many Relationship (Andy Kung)

ITPSB — Tue, 13 Mar 2012 23:36:56 GMT

Added Tom C code and it works like a charm! Many thanks Tom C.

re: How to Create a Many-to-Many Relationship (Andy Kung)

ITPSB — Tue, 13 Mar 2012 23:00:10 GMT

Hi Andy

Many thanks for the very useful tutorial.

A question: How can I enable multi-select of items to be added or removed (using shift/Ctrl-Select)?

Best regards, Mark.

re: How to Create a Many-to-Many Relationship (Andy Kung)

tpittson — Thu, 08 Mar 2012 15:13:28 GMT

I am using this with 3 tables Tires, Compatible Tractors, and Tractors. I want Tractors in list of Tractors to be copied to the Compatible Tractors table. I think I have the relationships set up correctly. I have the UI set up so I looks like Andy's but when I push the add Tractor button the compatible Tractors list just as a 0 and not the name of the tractor.

Can someone let me know what I could be missing.

thanks

re: How to Create a Many-to-Many Relationship (Andy Kung)

gmach — Fri, 27 Jan 2012 12:34:06 GMT

Andy, much thanks. Been puzzled since many-to-many was rejected in relationship dialog (LightSwitch 1.0)and have been scouring books and forums for an answer.

re: How to Create a Many-to-Many Relationship (Andy Kung)

andy.kung — Fri, 06 Jan 2012 18:22:30 GMT

@JDM. You can set it on the data property. To specify the number of items in a page, select a collection proptery (ex. MovieGenres in this tutorial) and you will find a "No. of items to display per page" in Properties.

re: How to Create a Many-to-Many Relationship (Andy Kung)

andy.kung — Fri, 06 Jan 2012 18:15:33 GMT

@cte. The list in the example is directly bound to the Genre table. Removing an item in the list will remove the data from the Genre table, which is not what you want. So the answer is, unfortunately, no.