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Dynamically adding a OnValueSelect results in the list text not being rendered properly

Not sure if this is a bug or I'm missing something in when builder the rendertree but when trying to add a dynamically created combobox the combobox renders and binds to the data but the text values all appear to be empty. Here's a sample code fragment i'm using:

I should add that the event is being called fine - but nothing is show for each item in the bound list, it also appears that if I switch the render order so the field setting are rendered after the event call back then the combo displays correctly but the event never fires.

I've  also discovered that if I swap the childcontent section in debug with a hot reload it works as expected


var propInfoValue = o.GetType().GetProperty(propertyInfo.Name);

var constant = System.Linq.Expressions.Expression.Constant(o, o.GetType());

var exp = System.Linq.Expressions.MemberExpression.Property(constant, propertyInfo.Name);

builder.OpenComponent(0, typeof(Syncfusion.Blazor.DropDowns.SfComboBox));

builder.AddAttribute(1, "DataSource", sharedLookup.GetItems());

var defaultValue = propInfoValue.GetValue(o);

builder.AddAttribute(2, "Value", defaultValue);

builder.AddAttribute(3, "PlaceHolder", DisplayName);

builder.AddAttribute(4, "FloatLabelType", FloatLabelType.Always);

builder.AddAttribute(5, "ChildContent", (Microsoft.AspNetCore.Components.RenderFragment)((fieldSettingBuilder) =>



fieldSettingBuilder.AddAttribute(2, "Value", "ID");

fieldSettingBuilder.AddAttribute(3, "Text", "Name");



builder.AddAttribute(6, "ChildContent", (Microsoft.AspNetCore.Components.RenderFragment)((builderComboBoxEvents) =>



builderComboBoxEvents.AddAttribute(2, "OnValueSelect", EventCallback.Factory.CreateLookupEntry >>(this, ((e) => OnValueSelect(e))));




2 Replies 1 reply marked as answer

SP Sureshkumar P Syncfusion Team December 19, 2022 11:14 AM UTC

Hi Richard,

You can achieve your requirement by using the below code example on your application.

Find the code example here:


                                              b.AddAttribute(10, "ChildContent", (RenderFragment)(b2 =>


                                                    b2.OpenComponent<ComboBoxEvents<string, ComboData>>(11);

                                                    b2.AddAttribute(12, "OnValueSelect", Microsoft.AspNetCore.Components.CompilerServices.RuntimeHelpers.TypeCheck(EventCallback.Factory.Create<SelectEventArgs<string>>(this, DropDownChange)));




                                                    b2.AddAttribute(14, "Value", "DisplayValue");









Sureshkumar P

Marked as answer

RK Richard Kiernan December 19, 2022 11:25 AM UTC

Perfect thanks


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