Question

我正在尝试使用C＃在Windows应用商店应用中本地创建一个sqlite数据库。

我一直收到错误

不了解sqliteDataGroup ...

使用下面的数据模型创建表格时。我正在使用sqlite-net和扩展。

我有什么想法，做错了吗？

public class sqliteDataItem
{
    public sqliteDataItem()
    {

    }

    public sqliteDataItem(int Id, String title, String subtitle, String Image, String description, String itemcontent, int groupid)
    {
        this.Id = Id;
        this.Title = title;
        this.Subtitle = subtitle;
        this.Description = description;
        this.Image = Image;
        this.ItemContent = itemcontent;
        this.GroupId = groupid;
    }

    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }

    [ForeignKey(typeof(sqliteDataGroup))]
    public int GroupId { get; set; }
    public string Title { get; set; }
    public string Subtitle { get; set; }
    public string Description { get; set; }
    public string Image { get; set; }
    public string ItemContent { get; set; }
    [ManyToOne]
    public sqliteDataGroup sqliteDataGroup { get; set; }
    public override string ToString()
    {
        return this.Title;
    }
}


/// <summary>
/// Generic group data model.
/// </summary>
public class sqliteDataGroup
{
    public sqliteDataGroup()
    {

    }

    public sqliteDataGroup(int Id, String title, String subtitle, String Image, String description)
    {
        this.Id = Id;
        this.Title = title;
        this.Subtitle = subtitle;
        this.Description = description;
        this.Image = Image;
        this.Items = new List<sqliteDataItem>();
    }

    [PrimaryKey,AutoIncrement]
    public int Id { get; set; }
    public string Title { get; set; }
    public string Subtitle { get; set; }
    public string Description { get; set; }
    public string Image { get; set; }
    [OneToMany]
    public List<sqliteDataItem> Items { get; set; }

    public override string ToString()
    {
        return this.Title;
    }
}

Answer 1

首先，如果你想使用sqlite net

，我建议添加一个有用的外观

public static class SqLiteFacade
{
    private static SQLiteConnection _sqlLiteConnection;
    private static string _nameOfDatabase = "databaseName.db";

    public static async Task<bool> InitializeDatabase()
    {
        try
        {
            _sqlLiteConnection = new SQLiteConnection(new SQLitePlatformWinRT(), await GetPathOfDatabaseInstance(_nameOfDatabase));

            _sqlLiteConnection.CreateTable<SqliteDataItem>();
            _sqlLiteConnection.CreateTable<SqliteDataGroup>();

            return true;
        }
        catch (Exception ex)
        {
            return false;
        }
    }

    public static SQLiteConnection DbConnection
    {
        get
        {
            return _sqlLiteConnection;;
        }
    }

    public static async Task<string> GetPathOfDatabaseInstance(string databaseName)
    {
        if (!await DatabaseExist(databaseName))
        {
            var sampleFile = await ApplicationData.Current.LocalFolder.CreateFileAsync(databaseName, CreationCollisionOption.ReplaceExisting);
        }

        var database = await ApplicationData.Current.LocalFolder.GetFileAsync(databaseName);
        return database.Path;
    }

    private static async Task<bool> DatabaseExist(string databaseName)
    {
        var files = await ApplicationData.Current.LocalFolder.GetFilesAsync();

        return files.Any(file => file.Name == databaseName);
    }
}

你的模特：

public class SqliteDataGroup
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }
    public string Title { get; set; }
    public string Subtitle { get; set; }
    public string Description { get; set; }
    public string Image { get; set; }
    [OneToMany(CascadeOperations = CascadeOperation.All)]
    public List<SqliteDataItem> Items { get; set; }
}

public class SqliteDataItem
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }
    public string ItemContent { get; set; }
    [ForeignKey(typeof(SqliteDataGroup))]
    public int SqliteDataGroupId { get; set; }
}

现在您可以使用并验证您的解决方案：

    if (await SqLiteFacade.InitializeDatabase())
    {
        var group = new SqliteDataGroup()
        {
            Description = "desc",
            Title = "my title",
            Image = "img",
            Subtitle = "subtitle",
            Items = new List<SqliteDataItem>()
                {
                    new SqliteDataItem()
                    {
                        ItemContent = "Item 1"
                    },
                    new SqliteDataItem()
                    {
                        ItemContent = "Item 2"
                    },
                    new SqliteDataItem()
                    {
                        ItemContent = "Item 3"
                    }
                }
        };

        SqLiteFacade.DbConnection.InsertWithChildren(group);
        var results = SqLiteFacade.DbConnection.GetAllWithChildren<SqliteDataGroup>();
    }

检查结果中是否为操作结果。就我而言，我只使用this nuget。首先卸载其他扩展。然后，您可以尝试使用基于this

的异步操作

使用datamodel c＃windows Store App创建sqlite数据库

1 个答案: