question

Hi,@EduardoGomez-1870. Welcome Microsoft Q&A.

The complete code required is shown below.
Xaml:

  <Window.Resources>
         <Thickness x:Key="tbMargin">0,10,0,0</Thickness>
     </Window.Resources>
    
     <Window.DataContext>
         <local:PrpertiesWindowViewModel />
     </Window.DataContext>
    
     <Border Padding="20" Width="300">
         <StackPanel>
             <TextBox materialDesign:HintAssist.Hint="Name of the building" materialDesign:HintAssist.IsFloating="True" />
    
             <TextBox  materialDesign:HintAssist.Hint="Description"  materialDesign:HintAssist.IsFloating="True" />
    
             <ComboBox  materialDesign:HintAssist.Hint="Rooms" materialDesign:HintAssist.IsFloating="True"
                        ItemsSource="{Binding Rooms}" IsReadOnly="True" />
    
             <TextBox    materialDesign:HintAssist.Hint="Address"   materialDesign:HintAssist.IsFloating="True" />
    
             <ListBox Visibility='Collapsed' />
    
         </StackPanel>
     </Border>

Codebehind:

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Net.Http;
 using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 using System.Windows;
 using Newtonsoft.Json;
    
 namespace SuggestionDemo
 {
   public partial class MainWindow : Window
   {
     public MainWindow()
     {
       InitializeComponent();
     }
   }
   public class PrpertiesWindowViewModel : BaseViewModel
   {
    
     public List<int> Rooms { get; set; }
    
     public PrpertiesWindowViewModel()
     {
    
       Rooms = new List<int>();
       FillList();
    
     }
    
     private void FillList()
     {
    
       for (int i = 1; i < 50; i++)
       {
         Rooms.Add(i);
       }
     }
   }
   public class BingSuggestions
   {
     private static readonly string subscriptionKey = "89d284162a144c0d887cf725a5cffecf";
     private static readonly string baseUri = "https://api.bing.microsoft.com/v7.0/suggestions";
     private const string QUERY_PARAMETER = "q?=";
     private const string MKT_PARAMETER = "&mkt=en-us";
    
     public static async Task<List<string>> CallApi(string query)
     {
    
       using (var client = new HttpClient())
       {
    
         var list = new List<string>();
    
         client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", subscriptionKey);
    
         var content = await client.GetAsync($"{baseUri}?{QUERY_PARAMETER}{query}{MKT_PARAMETER}");
    
         if (content.IsSuccessStatusCode)
         {
    
           string jsonContent = await content.Content.ReadAsStringAsync();
           SearchSuggestion response = JsonConvert.DeserializeObject<SearchSuggestion>(jsonContent);
    
           if (response.Query != null)
           {
             list.Add(response.Query);
           }
         }
    
         return list;
       }
     }
   }
    
   public class QueryContext
   {
    
     [JsonProperty("originalQuery")]
     public string? OriginalQuery { get; set; }
   }
    
   public class SearchSuggestion
   {
    
     [JsonProperty("url")]
     public string? Url { get; set; }
    
     [JsonProperty("displayText")]
     public string? DisplayText { get; set; }
    
     [JsonProperty("query")]
     public string? Query { get; set; }
    
     [JsonProperty("searchKind")]
     public string? SearchKind { get; set; }
   }
    
   public class SuggestionGroup
   {
    
     [JsonProperty("name")]
     public string? Name { get; set; }
    
     [JsonProperty("searchSuggestions")]
     public IList<SearchSuggestion>? SearchSuggestions { get; set; }
   }
    
   public class AutoSuggest
   {
    
     [JsonProperty("_type")]
     public string? Type { get; set; }
    
     [JsonProperty("queryContext")]
     public QueryContext? QueryContext { get; set; }
    
     [JsonProperty("suggestionGroups")]
     public IList<SuggestionGroup>? SuggestionGroups { get; set; }
   }
      public class BaseViewModel : INotifyPropertyChanged
   {
     private string? title = string.Empty;
    
     private string? subtitle = string.Empty;
    
     private string? icon = string.Empty;
    
     private bool isBusy;
    
     private bool isNotBusy = true;
    
     private bool canLoadMore = true;
    
     private string? header = string.Empty;
    
     private string? footer = string.Empty;
    
     public string? Title
     {
       get
       {
         return title;
       }
       set
       {
          
         SetProperty(ref title, value, "Title");
       }
     }
    
     public string? Subtitle
     {
       get
       {
         return subtitle;
       }
       set
       {
          
         SetProperty(ref subtitle, value, "Subtitle");
       }
     }
    
     public string? Icon
     {
       get
       {
         return icon;
       }
       set
       {
            
         SetProperty(ref icon, value, "Icon");
       }
     }
    
     public bool IsBusy
     {
       get
       {
         return isBusy;
       }
       set
       {
         
         if (SetProperty(ref isBusy, value, "IsBusy"))
         {
           IsNotBusy = !isBusy;
         }
       }
     }
    
    
     public bool IsNotBusy
     {
       get
       {
         return isNotBusy;
       }
       set
       {
        
         if (SetProperty(ref isNotBusy, value, "IsNotBusy"))
         {
              
           IsBusy = !isNotBusy;
         }
       }
     }
    
     
     public bool CanLoadMore
     {
       get
       {
         return canLoadMore;
       }
       set
       {
      
         SetProperty(ref canLoadMore, value, "CanLoadMore");
       }
     }
    
     public string? Header
     {
       get
       {
         return header;
       }
       set
       {
            
         SetProperty(ref header, value, "Header");
       }
     }
    
     public string? Footer
     {
       get
       {
         return footer;
       }
       set
       {
         
         SetProperty(ref footer, value, "Footer");
       }
     }
     protected virtual bool SetProperty<T>(ref T backingStore, T value, [CallerMemberName] string propertyName = "", Action? onChanged = null, Func<T, T, bool>? validateValue = null)
     {
       if (EqualityComparer<T>.Default.Equals(backingStore, value))
       {
         return false;
       }
    
       if (validateValue != null && !validateValue!(backingStore, value))
       {
         return false;
       }
    
       backingStore = value;
       onChanged?.Invoke();
       OnPropertyChanged(propertyName);
       return true;
     }
     protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = "")
     {
       this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
     }
     public event PropertyChangedEventHandler? PropertyChanged;
   }

The result:

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