accesso ai dati locali tramite sqllite

Modulo4/EsempioAccessoDatiLocali/Droid/SqlLite_Android.cs

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+using System;
+using System.IO;
+using Xamarin.Forms;
+using EsempioAccessoDatiLocali.Droid;
+
+
+
+[assembly: Dependency (typeof (SQLite_Android))]
+
+/// <summary>
+/// https://github.com/xamarin/xamarin-forms-samples/blob/master/Todo/PCL/Todo.Android/SQLite_Android.cs
+/// </summary>
+namespace EsempioAccessoDatiLocali.Droid
+{
+	public class SQLite_Android : ISQLite
+	{
+		public SQLite_Android ()
+		{
+		}
+
+		#region ISQLite implementation
+		public SQLite.SQLiteConnection GetConnection ()
+		{
+			var sqliteFilename = "TodoSQLite.db3";
+			string documentsPath = System.Environment.GetFolderPath (System.Environment.SpecialFolder.Personal); // Documents folder
+			var path = Path.Combine(documentsPath, sqliteFilename);
+
+			// This is where we copy in the prepopulated database
+			Console.WriteLine (path);
+
+			/*
+			 * nel caso dovessi usare un database pre-popolato
+			if (!File.Exists(path))
+			{
+				var s = Forms.Context.Resources.OpenRawResource(Resource.Raw.TodoSQLite);  // RESOURCE NAME ###
+
+				// create a write stream
+				FileStream writeStream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write);
+				// write to the stream
+				ReadWriteStream(s, writeStream);
+			}
+			*/
+
+			var conn = new SQLite.SQLiteConnection(path);
+
+			// Return the database connection 
+			return conn;
+		}
+		#endregion
+
+		/// <summary>
+		/// helper method to get the database out of /raw/ and into the user filesystem
+		/// </summary>
+		void ReadWriteStream(Stream readStream, Stream writeStream)
+		{
+			int Length = 256;
+			Byte[] buffer = new Byte[Length];
+			int bytesRead = readStream.Read(buffer, 0, Length);
+			// write the required bytes
+			while (bytesRead > 0)
+			{
+				writeStream.Write(buffer, 0, bytesRead);
+				bytesRead = readStream.Read(buffer, 0, Length);
+			}
+			readStream.Close();
+			writeStream.Close();
+		}
+	}
+}
+

Modulo4/EsempioAccessoDatiLocali/Droid/packages.config

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+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="sqlite-net-pcl" version="1.0.11" targetFramework="MonoAndroid50" />
+  <package id="SQLitePCL.raw_basic" version="0.7.1" targetFramework="MonoAndroid50" />
+  <package id="Xamarin.Android.Support.v4" version="22.1.1.1" targetFramework="MonoAndroid50" />
+  <package id="Xamarin.Forms" version="1.4.2.6359" targetFramework="MonoAndroid50" />
+</packages>

Modulo4/EsempioAccessoDatiLocali/EsempioAccessoDatiLocali/Database/Database.cs

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+using System;
+using System.Linq;
+using SQLite;
+using Xamarin.Forms;
+using System.Collections.Generic;
+
+namespace EsempioAccessoDatiLocali
+{
+	public class TodoItemDatabase 
+	{
+		static object locker = new object ();
+
+		SQLiteConnection database;
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="Tasky.DL.TaskDatabase"/> TaskDatabase. 
+		/// if the database doesn't exist, it will create the database and all the tables.
+		/// </summary>
+		/// <param name='path'>
+		/// Path.
+		/// </param>
+		public TodoItemDatabase()
+		{
+			var db = DependencyService.Get<ISQLite> ();
+
+			database = db.GetConnection ();
+			// create the tables
+			database.CreateTable<TodoItem>();
+		}
+
+		public IEnumerable<TodoItem> GetItems ()
+		{
+			lock (locker) {
+				return (from i in database.Table<TodoItem>() select i).ToList();
+			}
+		}
+
+		public IEnumerable<TodoItem> GetItemsNotDone ()
+		{
+			lock (locker) {
+				return database.Query<TodoItem>("SELECT * FROM [TodoItem] WHERE [Done] = 0");
+			}
+		}
+
+		public TodoItem GetItem (int id) 
+		{
+			lock (locker) {
+				return database.Table<TodoItem>().FirstOrDefault(x => x.ID == id);
+			}
+		}
+
+		public int SaveItem (TodoItem item) 
+		{
+			lock (locker) {
+				if (item.ID != 0) {
+					database.Update(item);
+					return item.ID;
+				} else {
+					return database.Insert(item);
+				}
+			}
+		}
+
+		public int DeleteItem(int id)
+		{
+			lock (locker) {
+				return database.Delete<TodoItem>(id);
+			}
+		}
+	}
+}
+

Modulo4/EsempioAccessoDatiLocali/EsempioAccessoDatiLocali/Database/IDatabase.cs

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+using System;
+using SQLite;
+
+namespace EsempioAccessoDatiLocali
+{
+	public interface ISQLite {
+
+		SQLiteConnection GetConnection();
+
+	}
+}
+

Modulo4/EsempioAccessoDatiLocali/EsempioAccessoDatiLocali/Model/TodoItem.cs

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+using System;
+using SQLite;
+
+namespace EsempioAccessoDatiLocali
+{
+	public class TodoItem
+	{
+		public TodoItem ()
+		{
+		}
+
+		[PrimaryKey, AutoIncrement]
+		public int ID { get; set; }
+
+		public string Name { get; set; }
+
+		public string Notes { get; set; }
+
+		public bool Done { get; set; }
+	}
+}
+

Modulo4/EsempioAccessoDatiLocali/EsempioAccessoDatiLocali/PaginaMenuPrincipale.xaml

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+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="EsempioAccessoDatiLocali.PaginaMenuPrincipale">
+	<ContentPage.Content
+			Title="Acceso ai dati locali" Padding="20, 20, 20, 20">
+
+			  <Grid ColumnSpacing="20" RowSpacing="20">
+			    <Grid.RowDefinitions>
+			      <RowDefinition Height="*" />
+			      <RowDefinition Height="*" />
+			      <RowDefinition Height="*" />
+			    </Grid.RowDefinitions>
+
+			    <Grid.ColumnDefinitions>
+			      <ColumnDefinition Width="*" />
+			      <ColumnDefinition Width="*" />
+			    </Grid.ColumnDefinitions>
+
+			    <Grid Grid.Row="0" Grid.Column="0" BackgroundColor="Aqua"><Button x:Name="PrimoPulsante" Text=""></Button></Grid>
+			    <Grid Grid.Row="0" Grid.Column="1" BackgroundColor="Olive"><Button x:Name="SecondoPulsante" Text=""></Button></Grid>
+
+			    <Grid Grid.Row="1" Grid.Column="0" BackgroundColor="Olive"><Button x:Name="TerzoPulsante" Text=""></Button></Grid>
+			    <Grid Grid.Row="1" Grid.Column="1" BackgroundColor="Aqua"><Button x:Name="QuartoPulsante" Text=""></Button></Grid>
+
+			    <Grid Grid.Row="2" Grid.Column="0" BackgroundColor="Aqua"></Grid>
+			    <Grid Grid.Row="2" Grid.Column="1" BackgroundColor="Olive"></Grid>
+
+			  </Grid>
+
+	</ContentPage.Content>
+</ContentPage>

Modulo4/EsempioAccessoDatiLocali/EsempioAccessoDatiLocali/PaginaMenuPrincipale.xaml.cs

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+using System;
+using System.Linq;
+using System.Collections.Generic;
+
+using Xamarin.Forms;
+
+using SQLite;
+
+namespace EsempioAccessoDatiLocali
+{
+	public partial class PaginaMenuPrincipale : ContentPage
+	{
+		public PaginaMenuPrincipale ()
+		{
+			InitializeComponent ();
+
+			this.PrimoPulsante.Text = "Conta Elementi";
+			this.PrimoPulsante.Clicked +=  (object sender, EventArgs e) => {
+				contaElementi();
+			};
+
+			this.SecondoPulsante.Text = "Inserisci Elementi";
+			this.SecondoPulsante.Clicked += (object sender, EventArgs e) => {
+				inserisciElemento();
+			};
+
+			this.TerzoPulsante.Text = "Elimina Un Elemento";
+			this.TerzoPulsante.Clicked += (object sender, EventArgs e) => {
+				eliminaElemento();
+			};
+		}
+
+		private void contaElementi()
+		{
+			var items = App.Database.GetItems ().ToList();
+
+			DisplayAlert ("", "Recuperati nro elementi: " + items.Count (), "OK");
+
+		}
+
+		private void inserisciElemento()
+		{
+
+			TodoItem td = new TodoItem (){ 
+				ID = 0, // è nuovo da salvare
+				Name = "NuovoItem" + DateTime.Now.Ticks,
+				Notes = "NuovoItemNote" + DateTime.Now.Ticks
+			};
+			App.Database.SaveItem (td);
+
+			contaElementi ();
+		}
+
+		private void eliminaElemento()
+		{
+
+			var itemToDelete = App.Database.GetItems ().FirstOrDefault ();
+
+			if (itemToDelete != null) {
+				App.Database.DeleteItem (itemToDelete.ID);	
+			} else {
+				DisplayAlert ("", "non ci sono elementi da cancellare ", "OK");
+				return;
+			}
+
+			contaElementi ();
+		}
+	}
+}
+

Modulo4/EsempioAccessoDatiLocali/EsempioAccessoDatiLocali/packages.config

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+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="sqlite-net-pcl" version="1.0.11" targetFramework="portable-net45+win+wp80+MonoAndroid10+xamarinios10+MonoTouch10" />
+  <package id="SQLitePCL.raw_basic" version="0.7.1" targetFramework="portable-net45+win+wp80+MonoAndroid10+xamarinios10+MonoTouch10" />
+  <package id="Xamarin.Forms" version="1.4.2.6359" targetFramework="portable-net45+win+wp80+MonoAndroid10+xamarinios10+MonoTouch10" />
+</packages>