Why the Blazor UI component doesn't update after delete event?

Question

Why the Blazor UI doesn't update after delete event:

My Component:

<table class="table table-striped">
    <thead>
        <tr>
            <th>Id</th>
            <th>Name</th>
            <th>Example</th>
            <th></th>
        </tr>
    </thead>
    <tbody>
        @foreach (var trainingTechnique in TrainingTechniques) {
        <tr>
            <td>@trainingTechnique.Id</td>
            <td>@trainingTechnique.Name</td>
            <td>@trainingTechnique.Example</td>
            <td>
                <button type="button" 
                        class="btn btn-danger" 
                        @onclick="@(async () => await DeleteTechnique(trainingTechnique.Id))">
                    Delete
                </button>

            </td>
        </tr>
        }
    </tbody>
</table>

My Component code behind:

public class TrainingTechniqueViewPageBase : ComponentBase
    {
        public List<TrainingTechniqueView> TrainingTechniques { get; set; }
        [Inject] 
        public ITrainingTechniqueConsumer TrainingTechniqueConsumer { get; set; }

        protected TrainingTechniqueForm TrainingTechniqueForm { get; set; } 
        protected override async Task OnInitializedAsync()
        {
            TrainingTechniques = (await TrainingTechniqueConsumer.GetTechniques()).ToList();
        }

        public async void TrainingTechniqueForm_OnSave()
        {
            TrainingTechniques = (await TrainingTechniqueConsumer.GetTechniques()).ToList();
            StateHasChanged();
        }

        protected void AddTrainingTechnique()
        {
            TrainingTechniqueForm.Show();
        }

        protected async Task DeleteTechnique(int id)
        {
           await (TrainingTechniqueConsumer.DeleteTrainingTechnique(id));
            this.StateHasChanged();

        }
    }
}

The Delete Method:

public async Task DeleteTrainingTechnique(int id)
{
    await _httpClient.DeleteAsync($"training/trainingtechniques/{id}");
}

Answer 1

Solution 1: Reload the TrainingTechniques list from the source

private async Task Delete(int id)
{
    await TrainingTechniqueConsumer.DeleteTrainingTechnique(id);
    TrainingTechniques = (await TrainingTechniqueConsumer.GetTechniques()).ToList();
}

Solution 2: Remove the item form the list:

<table class="table table-striped">
    <thead>
        <tr>
            <th>Id</th>
            <th>Name</th>
            <th>Example</th>
            <th></th>
        </tr>
    </thead>
    <tbody>
        @foreach (var trainingTechnique in TrainingTechniques)
        {
            <tr>
                <td>@trainingTechnique.Id</td>
                <td>@trainingTechnique.Name</td>
                <td>@trainingTechnique.Example</td>
                <td>
                    <button type="button" class="btn btn-danger" @onclick="@(() => DeleteTechnique(trainingTechnique.Id))">Delete</button>
                </td>
            </tr>
        }
    </tbody>
</table>

And the Delete method:

private async Task Delete(int id)
{
    TrainingTechniques.RemoveAll(x => x.Id == Id);
    await TrainingTechniqueConsumer.DeleteTrainingTechnique(id);
}

Answer 2

Remove the item from the list that has the binding to the UI.

protected async Task DeleteTechnique(int id)
{
    await (TrainingTechniqueConsumer.DeleteTrainingTechnique(id));
    TrainingTechniques.Remove(TrainingTechniques.Single(x => x.Id == id));
}

I think it is better to pass the item it self instead of an Id. For example the delete could be:

protected async Task DeleteTechnique(TrainingTechniqueView corpse)
{
    await (TrainingTechniqueConsumer.DeleteTrainingTechnique(corpse.Id));
    TrainingTechniques.Remove(corpse);
}

Answer 3

I had the same problem and almost same UI as yours but my problem was instead of defining TrainingTechniques as List, I'd defined it as IEnumerable. So instead of:

public IEnumerable<TrainingTechniqueView> TrainingTechniques { get; set; }

I changed it as:

public List<TrainingTechniqueView> TrainingTechniques { get; set; }

And then using one of solutions suggested by @Inktkiller.