Quantcast
Channel: Active questions tagged blazor - Stack Overflow
Viewing all articles
Browse latest Browse all 4839

Blazor Error - Object reference not set to an instance of an object - Navigating to New Page [duplicate]

$
0
0

I get the following error when navigating to a new page from a page with a bound conrol:

Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]      Unhandled exception rendering component: Object reference not set to an instance of an object.System.NullReferenceException: Object reference not set to an instance of an object.

The same error also occurs if I update the search text box too quickly. The search function is executed with async IHttpClientFactory currently. If I don't set the list to null it doesn't display the updated results correctly but I believe this is also a problem.

Thoughts?

Razor Page

<SfTextBox Paceholder="Recipe Filter" Width="250px" @oninput="OnChange"></SfTextBox><SfListView TValue="clRecipe" DataSource="@recipeFiltered"><ListViewEvents TValue="clRecipe" Clicked="Click"></ListViewEvents><ListViewFieldSettings Id="RecipeID" Text="RecipeName" TValue="clRecipe" /></SfListView>private async Task OnChange(Microsoft.AspNetCore.Components.ChangeEventArgs e){    string str = e.Value.ToString();    recipeFiltered = null;    recipeFiltered = await RecipeService.getRecipeListNameFilter(str);}

Update

trying to ensure that the list is never null breaks the control. Currently the control never updates. I dont see how the referenced page solution solves the issue.

recipeFiltered.Add(new clRecipe());foreach ( clRecipe rep in await RecipeService.getRecipeListNameFilter(str)){    recipeFiltered.Add(rep);}

Updating the page code to remove the control when the list is null seems to be on the right track but still errors randomly and when changing pages.

@if (recipeFiltered is not null){<SfListView TValue="clRecipe" DataSource="@recipeFiltered"><ListViewEvents TValue="clRecipe" Clicked="Click"></ListViewEvents><ListViewFieldSettings Id="RecipeID" Text="RecipeName" TValue="clRecipe" /></SfListView>}

Viewing all articles
Browse latest Browse all 4839

Trending Articles



<script src="https://jsc.adskeeper.com/r/s/rssing.com.1596347.js" async> </script>