how do i populate a dropdown with data from my controller

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Joseph 14 posts 93 karma points

Sep 02, 2021 @ 19:36
0

How do I populate a dropdown with data from a controller?
Umbraco newbie here, sorry if this is a dumb question.

My goal: I have a partial view with a dropdown in it, I want to get JSON data from an api to populate it.

Right now I have a controller that calls the api, and returns the data in a List<>. However I can't call the controller from the view, and I suspect that isn't a great plan anyway. I would like to use the same controller that returns the partial view, but I don't think it goes through a controller, so I created a new one.

This is the method in my controller:
```
    [System.Web.Http.HttpGet]
    [Route("GetDropdownData")]
    public List<ReportDropdown> Index()
    {
        List<ReportDropdown> result = new List<ReportDropdown>();
        string json;

        using (WebClient wc = new WebClient())
        {
            json = wc.DownloadString("http://apiurl....");
        }

        result = JsonConvert.DeserializeObject<List<ReportDropdown>>(json);

        return result;

    }
```
This creates my List<> correctly. However I don't know how to get this data to my view. As near as I can tell, the partial view doesn't go through a controller before it is displayed, so I can't put it into viewdata which would be my first choice.

Any guidence?
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Nik 1625 posts 7295 karma points MVP 7x c-trib

Sep 02, 2021 @ 22:04

0

Hi Joseph,

Can you elaborate a bit more on how your Partial view is called as you don't appear to mention that in your original post?

Thanks

Nik

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Thomas Kassos 54 posts 265 karma points

Oct 01, 2021 @ 20:36

I am not sure If I understand correctly what you are trying to achieve but here is one approach.

Create a Controller which will be return a PartialView with the populated dropdown from the API

public class TestController :SurfaceController
{
    [ChildActionOnly]
    public ActionResult Index()
    {
        List<ReportDropdown> result = new List<ReportDropdown>();
        string json;

        using (WebClient wc = new WebClient())
        {
            json = wc.DownloadString("http://apiurl....");
        }

        result = JsonConvert.DeserializeObject<List<ReportDropdown>>(json);

        return PartialView("~/Views/Partials/{YourView}", result);
    }
}

Create the PartialView that the controller will return. Will look like that

    @inherits UmbracoViewPage<List<ReportDropdown>>

    <label for="myDropDown">My DropDown</label>
    <select name="myDropDown" id="myDropDown">
       <option disabled="disabled" value="">Please Select...</option>
       @foreach (var item in Model)
       {
           <option value="@item">@item</option>
       }
   </select>

And in your page call that controller to get the populated dropdown

@Html.Action("Index","Test")

and you will get only a dropdown with the api values

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Joseph 14 posts 93 karma points

Oct 01, 2021 @ 20:38

0

What do you mean "The actual page that is connected with the doctype"?

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Thomas Kassos 54 posts 265 karma points

Oct 01, 2021 @ 22:28
0
Hi Joseph,

Forget that, I correct it in my answer. Also, I fixed and some bits in my code.

Once you have create the controller and the PartialView you can use that
```
@Html.Action("Index","Test")
```
in any view to get the dropdown
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Joseph 14 posts 93 karma points

Oct 04, 2021 @ 14:42
0
Thank you for this, I am trying to get Html.Action working but get an error that there is no route that matches. Here is what I am trying to do:

Controller:
```
public class TestController : BaseController
{
    [Route("TestView")]
    public ActionResult TestView()
    {
        string modelString = "Test String";
        return View("~/Views/Test/TestView.cshtml", modelString);
    }
}
```
The HTML view I am trying to pull in is as basic as it gets:
```
@model string

@Model
```
And this is where I am trying to call the controller:
```
@Html.Action("Test","TestView")
```
Any idea why this is not working? If I can figure out how to get data from the controller like this it would be amazing.
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Thomas Kassos 54 posts 265 karma points

Oct 04, 2021 @ 14:53
100
Hi,

you can copy my example and it will probably work.

In your code sample I can see 4-5 issues.
- In the controller: remove the [Route("TestView")] attribute
- In the controller: you need to return a PartialView (see my code). And place your html you want to return inside ~/Views/Partials/Test/TestView.cshtml
- In the controller: Does the BaseController inherit for the SurfaceController ? if not replace it with the SurfaceController
- In the partial view replace
@model string

with
```
@inherits UmbracoViewPage<string>
```
maybe its the same thing I am not sure but just in case do that I know it works
- and in the view its @Html.Action("{actionResultName}", "{controllername}") so in your case @Html.Action("TestView", "Test")
Optionally but good to have use the [ChildActionOnly], see my example. With this one your controller will be more secure and will be called only from your c# code. For example You will not be able to call that controller with ajax
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Joseph 14 posts 93 karma points

Oct 04, 2021 @ 15:08

0

Made the changes you suggested, getting the same result. To be clear it is erroring on Html.Action, and never reaches my test controller. Here is a summary of what I changed:

Switched the Html.Action to use the method name first and the controller name second.

Moved the view into the partials folder.

In the partial view, Instead of using a model I just typed in "This is working!" to simplify the test.

Removed the route attribute in the test controller.

Any idea what I can check next?

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Joseph 14 posts 93 karma points

Oct 04, 2021 @ 15:10

0

In response to your edit, inheriting from SurfaceController did the trick, thank you!

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Thomas Kassos 54 posts 265 karma points

Oct 04, 2021 @ 15:11

0

Nice!! we got it working!

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Joseph 14 posts 93 karma points

Oct 04, 2021 @ 15:16

0

Looks like our BaseController inherits from RenderMvcController. What is the difference between RenderMvcController and SurfaceController?

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Thomas Kassos 54 posts 265 karma points

Oct 04, 2021 @ 15:27

0

you can read more here

https://our.umbraco.com/documentation/Implementation/Controllers/

In sort with a RenderMvcController you could overwrite the default route of Umbraco and return a page through your custom controller. Or return all the pages through that controller. https://our.umbraco.com/Documentation/Implementation/Default-Routing/Controller-Selection/index-v8

https://our.umbraco.com/Documentation/Reference/Routing/custom-controllers-v8

The surface controllers are auto-routed, they return only partial views. They are good for things like this one or for a form submission. I think the surface controllers are the most common to use.

Also that [Route] attributes I don't think they will work the Surface controller, maybe with the UmbracoApiController if I am wrong.

you can read more about routing here https://our.umbraco.com/Documentation/Reference/Routing/custom-routes-v8

https://our.umbraco.com/Documentation/Reference/Routing/surface-controllers-v8

General speaking if you search into Umbraco Documentation, you will find what you need with a good example.

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How do I populate a dropdown with data from a controller?