Checking if value exists in array-CodePudding

Checking if "Item1" exists in ArrayOfItems.

For example, if I check simple condition like @if("Item1 == "Item1"), it returns true and displays dropdown items. But ArrayOfItems.Contains("Item1") always returns false, even though ArrayOfItems has "Item1" and "Item2"

      @if (ArrayOfItems.Contains("Item1")) // this always returns false
      {
        <li >
            <input type="checkbox" id="cb4" data-id=3>
            <label for="cb4"> Item Height/label>
        </li>

         <li >
         <input type="checkbox" id="cb5" data-id=4>
         <label for="cb5"> Item Width </label>
         </li>
     }

    @code {        
        public string ItemName{ get; set; }
        List<string> ArrayOfItems= new List<string>();     

                private void HandleNameSent(string ItemName)
        {            
            JSRuntime.InvokeVoidAsync("console.log", "ItemName", ItemName);
            ArrayOfItems.Add(ItemName);
            JSRuntime.InvokeVoidAsync("console.log", "ArrayOfItems", ArrayOfItems);  // returns an array with two values "Item1" and "Item2"        
        }

     
   }

May I know what could be the reason. Thank you.

CodePudding user response：

Initially when the page was rendered, ArrayOfItems was empty.

Whenever data gets updated after the page has already initialized, you need to call StateHasChanged() to re-render with the updated data.

private void HandleNameSent(string ItemName)
{            
    JSRuntime.InvokeVoidAsync("console.log", "ItemName", ItemName);
    ArrayOfItems.Add(ItemName);
    StateHasChanged();
    JSRuntime.InvokeVoidAsync("console.log", "ArrayOfItems", ArrayOfItems);       
}

CodePudding user response：

Check this question here: If/else is not working properly with using OnInitiliazedAsync in Blazor C#

I hope you'll get the answer. You need to add a check first.