Adding htmlattributes to DropDownList helper changes behaviour

Question

Prior to MVC 5 the DropDownList was scaffolded in my Razor Edit View as:

@Html.DropDownList("EntityId", String.Empty)

But now the equivalent (post MVC 5) is scaffolded as:

@Html.DropDownList("EntityId", null, htmlAttributes: new { @class = "form-control" })

I want to add the htmlAttributes to keep the UI consistent, but the DropDownList no longer works as expected for a nullable EntityId (int ? EntityId). The problem is that the default item is set to the first item in the list if EntityId is null. I want a blank item if the id is null, and the appropriate selection if not.

PS. My controller builds the list as follows: ViewBag.EntityId = new SelectList(db.Entities, "EntityId", "Name", EntityId);

Does your model have a property your binding to? (you should not have the same name for the model property and the ViewBag SelectList property) — user3559349
– user3559349, Commented Dec 16, 2014 at 5:01
Yes it does, could that be causing the problem? Not sure why I ever did this, but I suspect it is like that in a lot of my code. I have just seen your reply below, and will try this out back at work tomorrow. Thx — tr3v
– tr3v, Commented Dec 16, 2014 at 8:58
Just noticed why I use the same property name for both the model and ViewBag - it is because it is scaffolded that way in the controller by default - something to be aware of. — tr3v
– tr3v, Commented Jan 5, 2015 at 21:41

score 4 · Accepted Answer · 2014-12-16 08:59:02Z

4

Use the strongly typed helpers. If your model has a property int? EntityId, then in the controller

ViewBag.EntityList = new SelectList(db.Entities, "EntityId", "Name")

Note the ViewBag property should not be the same name as the model property, and the 3rd parameter of 'SelectList` is not required.

Then in the view

@Html.DropDownListFor(m => m.EntityId, (SelectList)ViewBag.EntityList, "--Please select--", new  { @class = "form-control" })

If EntityId is null, the first option will be selected, otherwise if EntityId matches the value of one of your options then it will be selected.

edited Dec 16, 2014 at 8:59

answered Dec 16, 2014 at 5:14

user3559349

Sign up to request clarification or add additional context in comments.

4 Comments

tr3v Over a year ago

Do you mean ViewBag.EntityList not Model.EntityList?

user3559349 Over a year ago

Yes I do :) will update in a momement (I always use view models and hate ViewBag)

tr3v Over a year ago

That did it thanks - the name of the ViewBag property didn't seem to make any difference though. Is there a specific reason why the ViewBag property and model property names can't be the same? Just curious.

tr3v Over a year ago

I was wrong - if the ViewBag property name is the same as the Model property name, then the selected item is not selected, and this was the source of my problems from the outset.

a_hardin · Accepted Answer · 2014-12-16 18:18:33Z

1

Modify your @HTML.DropDownList to

@Html.DropDownList("EntityId", (SelectList)Viewbag.EntityList,String.Empty, new { @class = "form-control" })`

edited Dec 16, 2014 at 18:18

a_hardin

5,2774 gold badges34 silver badges40 bronze badges

answered Dec 16, 2014 at 8:52

nikhil kandalkar

1911 silver badge8 bronze badges

1 Comment

tr3v Over a year ago

This worked too thanks, once I added a cast for the SelectList (edited your post). Thanks.

Collectives™ on Stack Overflow

Adding htmlattributes to DropDownList helper changes behaviour

2 Answers 2

4 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related