Added Persistence with LINQ

src/Banquale/Banquale/DataContractPersistance/DataContractPersLINQ.cs

@@ -0,0 +1,46 @@
+using Model;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Xml.Linq;
+using System.Xml;
+
+namespace Banquale.DataContractPersistance
+{
+    public class DataContractPersLINQ : IPersistenceManager
+    {
+
+        public string FilePath { get; set; } = FileSystem.Current.AppDataDirectory;
+        public string FileName { get; set; } = "DataSave.xml";
+
+        public (HashSet<Customer>, Consultant) DataLoad()
+        {
+            throw new NotImplementedException();
+        }
+
+        public void DataSave(HashSet<Customer> cu, Consultant co)
+        {
+            XDocument dataSave = new XDocument();
+
+            var save = cu.Select(v => new XElement("Customer",
+                                                    new XElement("Personne",
+                                                        new XElement("name", v.FirstName),
+                                                        new XElement("id", Convert.ToString(v.Id)),
+                                                        new XElement("mdp", v.Password),
+                                                    new XAttribute("Account", v.AccountsList))));
+
+            dataSave.Add(new XElement("Customers", save));
+
+            XmlWriterSettings settings = new XmlWriterSettings();
+            settings.Indent = true;
+
+            using (TextWriter tw = File.CreateText(Path.Combine(FilePath, FileName)))
+            using (XmlWriter writer = XmlWriter.Create(tw, settings))
+            {
+                dataSave.Save(writer);
+            }
+        }
+    }
+}