从JavaScript调用C＃函数背后的代码

Question

I know this has been asked, but none of the numerous answers fit with my situation. So I will humbly ask if someone can walk me through this again gently.

Environment: .Net 4 web app using c#, javascript, jquery, sql server, and entity framework.

Question: I need to be able to allow a user to "quick add" a value into a table that is bound to a drop down box without losing values a user has already entered onto current page. I don't care if I have to do a postback or use jquery or use ajax, etc. I need the functionality first - prettiness later ... the scenario is described below if you care to keep reading. With all that being said, I would love for this to be smooth and not "clunky" for the user.

Scenario: I have a page where the user is able to enter many pieces of information into textboxes, static drop down boxes, and drop down boxes that are bound to other tables that will all get combined and inserted into one table. Well, it never fails, a user could be filling in the page and when they get to one of the table bound drop down boxes - a value is missing or they haven't added something item yet. I would like to add a button or link or something next to that drop down box that would allow the user to "quick add" an item to the table that fills that drop down box and then refresh the drop down box so they can choose that new value from the list ... all while not losing the other data on the screen they already entered.

What I've tried: -Tried WebMethod option. Currently, this web page calls some custom "bind" methods in the code behind to fill drop down boxes so they are not filled directly from objects from entity framework. So that means using a static method will not work for a solution because part of the static function would need to call the bind method to refresh the drop down box with the newly inserted values.

-Tried PageMethod option. Some of the other samples used Page Method settings, but my site uses master and content pages and the posts seem to state that the page method route was not going to work.

Make sense?

Answer 1

Add an UpdatePanel to the page. The update panel should wrap the drop down to be added, as well as the textbox/button for adding a new entry to that drop down. You would want to have a different UpdatePanel for each dropdown/button pair, if applicable.

When they click the button inside of the update panel you can read the textbox, add an extra item to the drop down, and send an update to the database. (I'd manually add the new value to the drop down rather than updating the database and re-binding, if possible, but it may not be.)

The magic of UpdatePanels will make sure that this is all asynchronous and so doesn't disturb the user working on the page.