How to add style for every listbox.Item in code behind?

Question

i am trying to add different styles for every listbox.Item in my project. Can anyone help me about that?

`

            foreach (var item in orderList)
            {
                var itm = new ListBoxItem();

                if (item.CustomOrder)
                {
                    itm.Content = item;
                    itm.Style = customOrderStyle;
                    listbox.Items.Add(itm);


                }
                else
                {
                    itm.Content = item;
                    itm.Style = newOrderStyle;
                    listbox.Items.Add(itm);


                }
            }

`

I know that i am adding Listbox item to the listbox, that's why content is doesnt shown. I try some different things too but still dont know how to solve it.

Answer 1

An example of a more typical for WPF implementation:

namespace Core2022.SO.Ali.ListBoxItemStyleSelector
{
    public class OrderItem
    {
        public bool CustomOrder { get; set; }

        public int Id { get; set; }
    }
}

using System.Collections.ObjectModel;

namespace Core2022.SO.Ali.ListBoxItemStyleSelector
{
    public class OrderViewModel
    {
        public ObservableCollection<OrderItem> Orders { get; } = new ObservableCollection<OrderItem>();

        public OrderViewModel()
        {
            for (int i = 0; i < 10; i++)
            {
                Orders.Add(new OrderItem() { Id = i, CustomOrder = i % 2 == 0 });
            }
        }
    }
}

using System;
using System.Windows;
using System.Windows.Controls;

namespace Core2022.SO.Ali.ListBoxItemStyleSelector
{
    public class CustomOrderStyleSelector : StyleSelector
    {
        public Style? CustomOrderTrue { get; set; }
        public Style? CustomOrderFalse { get; set; }

        public override Style SelectStyle(object item, DependencyObject container)
        {
            if (item is OrderItem order)
            {
                return (order.CustomOrder ? CustomOrderTrue : CustomOrderFalse)
                    ?? throw new NullReferenceException(); ;
            }
            return base.SelectStyle(item, container);
        }
    }
}

<Window x:Class="Core2022.SO.Ali.ListBoxItemStyleSelector.OrdersWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Core2022.SO.Ali.ListBoxItemStyleSelector"
        mc:Ignorable="d"
        Title="OrdersWindow" Height="300" Width="200"
        DataContext="{DynamicResource vm}">
    <FrameworkElement.Resources>
        <local:OrderViewModel x:Key="vm"/>
        <local:CustomOrderStyleSelector x:Key="customOrderStyleSelector">
            <local:CustomOrderStyleSelector.CustomOrderTrue>
                <Style TargetType="ListBoxItem">
                    <Setter Property="Foreground" Value="Green"/>
                    <Setter Property="FontSize" Value="15"/>
                </Style>
            </local:CustomOrderStyleSelector.CustomOrderTrue>
            <local:CustomOrderStyleSelector.CustomOrderFalse>
                <Style TargetType="ListBoxItem">
                    <Setter Property="Background" Value="Coral"/>
                    <Setter Property="HorizontalContentAlignment" Value="Center"/>
                </Style>
            </local:CustomOrderStyleSelector.CustomOrderFalse>
        </local:CustomOrderStyleSelector>
    </FrameworkElement.Resources>
    <Grid>
        <ListBox ItemsSource="{Binding Orders}"
                 DisplayMemberPath="Id"
                 ItemContainerStyleSelector="{DynamicResource customOrderStyleSelector}"/>
    </Grid>
</Window>