global razor helper umb 8

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Peter Cort Larsen 421 posts 1038 karma points

Nov 14, 2020 @ 11:11

Global razor helper umb 8

Hi,

I have made a cshtml file in App_Code with global helper methods.

The problem is that i get an exception after build.

Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0534: 'helper' does not implement inherited abstract member 'WebPageExecutingBase.Execute()'

Source Error:

Line 50:     public class helper : UmbracoViewPage {

My code look like this

@using System.Text.RegularExpressions
@using Umbraco.Core.Models.PublishedContent;
@inherits UmbracoViewPage

@helper RenderImage(dynamic i)
{
    var picture = "";
    if (i.HasValue("image"))
    {
        picture = i.Value<IPublishedContent>("image").Url();
        <img src="@picture" class="img-resp" />
    }
}

Can anyone help?

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Marc Goodson 2157 posts 14435 karma points MVP 9x c-trib

Nov 14, 2020 @ 21:34
0
Hi Peter

I'm not sure you need to inherit UmbracoViewPage at the top?
```
@inherits UmbracoViewPage
```
essentially you are saying that your @helper class inherits from UmbracoViewPage and this requires you to implement WebPageExecutingBase.Execute()

Which you 'could' do, but I think if you remove the @inherits statement then you won't need to and your helper will still work...

regards

Marc
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Peter Cort Larsen 421 posts 1038 karma points

Nov 15, 2020 @ 12:38
0
Hi,

Thanks that helped.

I have another problem after this.

In the global helper, how do i convert the dynamic object thats passed into the method into the correct type?

I tried something like this, but thats not correct
```
@helper RenderImage(object i)
{

    var type = i.GetType();

    var sc = (type)i;


        if (!string.IsNullOrEmpty(sc.Image.ToString()))
        {
            IPublishedContent picture = sc.Image;
            <img src="@picture.Url" class="img-resp" />
        }
}
```
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Søren Gregersen 441 posts 1884 karma points MVP 2x c-trib

Nov 15, 2020 @ 21:35
0
Hi,

The line var type = i.GetType(); gets information about a type, but not a type. In c# types are static, which means you need have it available at compile time.

Your RenderImage could be rewritten as:
```
@helper RenderImage(IPulishedContent c, string imageAlias = "Image")
{
    if(c==null) return;
    var image = c.Value<IPublishedContent>(imageAlias);
    if(image==null) return;

     <img src="@picture.Url" class="img-resp" />
}
```
Another rewrite could be:
```
@helper RenderImage(IContentWithImage c)
{
    if(c==null || c.Image == null) return;

     <img src="@c.Image.Url" class="img-resp" />
}
```
IContentWithImage would be a composition "Content With Image" that defines the Image-property
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Peter Cort Larsen 421 posts 1038 karma points

Nov 15, 2020 @ 12:39

0

I know this is a very simple example, i have other more complex stuff i would like to have in a global helper file.

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Peter Cort Larsen 421 posts 1038 karma points

Nov 16, 2020 @ 08:16

0

Hi ,

Thanks,

The problem is that i dont know the model beforehand, but all the models that use the helper has the same property.

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Peter Cort Larsen 421 posts 1038 karma points

Nov 16, 2020 @ 08:19

The calling razor looks like this:

@using MYMODELNAMESPACE.Models.ModelsBuilder;
@using Perplex.ContentBlocks.Rendering;

@model IContentBlockViewModel<TwoColumnImageVideoElement>
@{
    var imageSlider = Model.Content.FirstColumn;
}
@if (imageSlider.Any())
{
    foreach (var i in imageSlider)
    {
        var images = i.ImageItems;
        foreach (var img in images)
        {
            if (img.HasValue("image"))
            {
                var RenderImage = helper.RenderImage(img);
                @RenderImage
            }

        }
    }
}

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Marc Goodson 2157 posts 14435 karma points MVP 9x c-trib

Nov 16, 2020 @ 08:26
100
Hi Peter

What is the type of imageSlider and i.ImageItems?

IEnumerable<IPublishedContent> or IEnumerable<IPublishedElement> ??

It's hard to tell, but it's likely your img, implements IPublishedContent so you could probably use that as your type in your razor helper.
```
@helper RenderImage(IPublishedContent i)
```
??

If your razor helper, is rendering HTML would it be better to have another PartialView for rendering images, that you called like Html.Partial("RenderImagePartial", model);

rather than a razor helper?

or perhaps an extension method on HtmlHelper, so you could call it in your views like @Html.RenderImageHelper(model): https://docs.microsoft.com/en-us/aspnet/mvc/overview/older-versions-1/views/creating-custom-html-helpers-cs

regards

Marc
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Peter Cort Larsen 421 posts 1038 karma points

Nov 16, 2020 @ 10:25

Hi,

yes, this is the way.

 public static string RenderImage(IPublishedContent Image)
    {
        if (Image != null)
        {
            return String.Format("<img src='{0}' class='img-resp'/>", Image.Url());
        }
        return string.Empty;
    }

Then i can call it like this:

   @Html.Raw(UmbracoHelperExtensions.RenderImage(i.Image))

Thanks

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