public static async Task <ObservableCollection <Article> > LoadAsync()
{
using (var context = new ArticleContext())
{
#if DEBUG
//context.Database.EnsureDeleted(); // DB 削除
#endif
await context.Database.EnsureCreatedAsync(CancellationToken.None);
await EnsureInitialDataAsync();
ArticlesList = new ObservableCollection <Article>(await context.Articles.ToListAsync());
return(ArticlesList);
async Task EnsureInitialDataAsync()
{
if (await context.Articles.FirstOrDefaultAsync() != null)
{
return;
}
// set initial data
context.Articles.Add(new Article(1)
{
Title = "UWPアプリを書けばiOS／Android／Webでも動く!? ～Uno Platform：クロスプラットフォーム開発環境",
Url = "https://codezine.jp/article/detail/11795"
});
context.Articles.Add(new Article(2)
{
Title = "Uno Platform - Home",
Url = "https://platform.uno/"
});
context.Articles.Add(new Article(3)
{
Title = "Uno Platform Team Blog",
Url = "https://platform.uno/blog/"
});
var count = await context.SaveChangesAsync(CancellationToken.None);
#if DEBUG
Console.WriteLine("{0} records saved to database", count);
#endif
}
} //end using
}
public static async Task DeleteAsync(Article article)
{
if (!ArticlesList.Contains(article))
{
throw new ArgumentException("指定されたArticleオブジェクトはArticlesListに含まれていません。");
}
if (article.ArticleId > 0)
{
using (var context = new ArticleContext())
{
var targetItem
= await context.Articles.SingleAsync(m => m.ArticleId == article.ArticleId);
context.Articles.Remove(targetItem);
await context.SaveChangesAsync(CancellationToken.None);
}
}
ArticlesList.Remove(article);
}
// DBへの登録・更新
// 仮のデータのupdateは、DBへの新規登録となり、ArticleIdが採番される。
public static async Task <Article> UpdateAsync(Article originalArticle, Article newArticle)
{
if (!ArticlesList.Contains(originalArticle))
{
throw new ArgumentException("指定されたArticleオブジェクトはArticlesListに含まれていません。");
}
if (originalArticle.ArticleId != newArticle.ArticleId)
{
throw new ArgumentException("2つの引数でArticleIdが違います。");
}
if (originalArticle.Title == newArticle.Title && originalArticle.Url == newArticle.Url)
{
return(originalArticle);
}
Article modifiedArticle;
if (originalArticle.ArticleId > 0)
{
modifiedArticle = await UpdateDataAsync(originalArticle, newArticle);
}
else
{
modifiedArticle = await InsertDataAsync(newArticle);
}
// ObservableCollectionのデータを入れ替える（これでNotifyChangedが画面側に飛ぶ）
int updateItemPosition = ArticlesList.IndexOf(originalArticle);
ArticlesList.RemoveAt(updateItemPosition);
ArticlesList.Insert(updateItemPosition, modifiedArticle);
return(modifiedArticle);
async Task <Article> UpdateDataAsync(Article original, Article newData)
{
// 既存データの更新
using (var context = new ArticleContext())
{
// データベースから更新対象のデータを取ってくる
var targetItem
= await context.Articles.SingleAsync(m => m.ArticleId == original.ArticleId);
// 更新対象のデータを書き換え
targetItem.Title = newData.Title;
targetItem.Url = newData.Url;
// データベースに反映
await context.SaveChangesAsync(CancellationToken.None);
return(targetItem);
}
}
async Task <Article> InsertDataAsync(Article article)
{
// 新規データを追加（自動採番）
using (var context = new ArticleContext())
{
var newEntry = context.Articles.Add(new Article
{
Title = article.Title,
Url = article.Url,
});
await context.SaveChangesAsync(CancellationToken.None);
return(newEntry.Entity);
}
}
}