I'm using C# WPF and I have DataGrid that fill with MY LIST via SQL Server Data
I have this model :
public class HAVALEHA_MODEL
{
public double? NUMBER { get; set; }
public string NAME { get; set; }
public string CUST_NO { get; set; }
public long? DATE_N { get; set; }
public string TAH { get; set; }
public string MOLAH { get; set; }
public string SHARAYET { get; set; }
public int? ANBAR { get; set; }
public double? FNUMCO { get; set; }
public double? MAS { get; set; }
}
my list: public List<HAVALEHA_MODEL> LIST_HAVALEHA { get; set; } = new List<HAVALEHA_MODEL>();
I want to do a search in this DataGrid's Items, but I want the search to be done in such a way that a dynamic condition is automatically added for each field that is filled and finally the created condition is applied,
that is, if the user selects all the fields including the number, Fill in the number, date, etc., and make a condition for each one that is filled in, and finally apply it.
like this : 
What have I tried ? :
IEnumerable<HAVALEHA_MODEL> LINQ_SEARCH = null;
if (!string.IsNullOrEmpty(CUST_N_FLD))
{
LINQ_SEARCH = LIST_HAVALEHA.Where(x => !(x.NAME is null) && x.NAME.ToLowerInvariant().Contains(CUST_N_FLD.ToLowerInvariant()));
}
if (!string.IsNullOrEmpty(NUMBER_FLD))
{
LINQ_SEARCH = LIST_HAVALEHA.Where(x => !(x.NUMBER is null) && x.NAME.ToLowerInvariant().Contains(NUMBER_FLD.Text.Trim().ToLowerInvariant()));
}
MY_Data_Ggrid.ItemsSource = LINQ_SEARCH.ToList();
that is not correct and it won't work!
It is difficult to clearly and simply explain what I need exactly, please understand
please give me some advice