Question

I m having a little trouble coming up with a schema to order and changing order in a article/news management system.

Here goes:
I have News Object Model as follow:

 class News {
   int id;
   string Title;
   string Content;
   string OrderId;
   // trimmed
 }

I have CRUD for the object model. and List as follows:

Id Title Order
1. Foo    -+
2. Bar    -+
3. Glah   -+

What i want to do is when user clicks on – for first news, i want to replace 1 and 2 orderid and of course display as well.

well how do i do this on server side? lets say for 1. item order id is 1 , how do i find the first item that has a higher order id then this one?

Or take 2. Bar, when i click on – , how do i find/replace order ids with first one. or i click on + how do i replace order id of this news with 3. Glah ?

is there a better way of doing this?

There are also some UI where user drags and drops ? any pointers on that?

Answer 1

When the user changes the location of an item, the server needs to know which item was changed and what it’s new position is. In the code below, I’m using a List to figure out the new positons. In this sample code, newPosition is the new zero-based position and selectedArticle is the article that was moved.

List<Article> articles = LoadSortedArticles()
articles.Remove(selectedArticle);
articles.Insert(newPosition, selectedArticle);
UpdateArticles(articles);

After running, the article’s index within the list tells you its new position. That applies to all articles in the list and works the same for a drag/drop UI. I don’t know entity framework, but if you can map the orderId field in the database to the index of the article in the list, then you should be good to go.

I hope this is at least able to give you some ideas. Maybe someone else can give a solution specific to entity framework, but I think putting the articles into a sorted list and letting the list do the work might be the easiest way.