无法在Xamarin Android项目中读取SQLite文件

Question

我有一个名为Lego_Parts.db3的文件，这是一个已经填充了数据的SQLite文件。我将其放在Android Xamarin项目的资产文件夹中。我必须设置数据库路径的代码是：

static PieceDB database;

        public static PieceDB PieceDatabase
        {
            get
            {
                if (database == null)
                {
                    database = new PieceDB(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "Lego_Parts.db3"));
                }
                return database;
            }
        }

[当我尝试显示数据库中的数据（在DatabaseTest.xaml中时，没有数据显示）

这里是任何适用的代码：

Piece.cs

using SQLite;

namespace TestApp1
{
    public class Piece
    {
        public int PartNum { get; set; }
        public string PartName { get; set; }
        public string Catagory { get; set; }
        public string Url { get; set; }
    }
}

PieceDB.cs]​​>

using SQLite;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;

namespace TestApp1
{
    public class PieceDB
    {
        readonly SQLiteAsyncConnection _database;

        public PieceDB(string dbPath)
        {
            _database = new SQLiteAsyncConnection(dbPath);
            _database.CreateTableAsync<Piece>().Wait();
        }

        public Task<List<Piece>> GetAllPieces()
        {
            return _database.Table<Piece>().ToListAsync();
        }

        public Task<Piece> GetPiece(int partNum)
        {
            return _database.Table<Piece>().Where(i => i.PartNum == partNum).FirstOrDefaultAsync();
        }

        public Task<int> SavePieceAsync(Piece temp)
        {
            return _database.InsertAsync(temp);
        }
    }
}
DatabaseTest.xaml.cs

using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace TestApp1
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class DatabaseTest : ContentPage
    {

        protected override async void OnAppearing()
        {
            base.OnAppearing();

            listView.ItemsSource = await App.PieceDatabase.GetAllPieces();
        }

        public DatabaseTest()
        {
            InitializeComponent();
        }

        async void Handle_ItemTapped(object sender, ItemTappedEventArgs e)
        {
            if (e.Item == null)
                return;

            await DisplayAlert("Item Tapped", "An item was tapped.", "OK");

            //Deselect Item
            ((ListView)sender).SelectedItem = null;
        }
    }
}
DatabaseTest.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:d="http://xamarin.com/schemas/2014/forms/design"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d"
             x:Class="TestApp1.DatabaseTest">
    <StackLayout Margin="20,35,20,20">
        <ListView x:Name="listView">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <TextCell Text="{Binding PartNum}"
                              Detail="{Binding Url}"
                              />
                </DataTemplate>
            </ListView.ItemTemplate>

        </ListView>
    </StackLayout>
</ContentPage>

我有一个名为Lego_Parts.db3的文件，这是一个已经填充了数据的SQLite文件。我将其放在Android Xamarin项目的资产文件夹中。我必须设置数据库路径的代码是：...

Answer 1

您将必须将数据库复制到文件位置。