osu/osu.Game/Database/MutableDatabaseBackedStore.cs
2019-11-17 20:48:23 +08:00

151 lines
5.0 KiB
C#

// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using osu.Framework.Platform;
namespace osu.Game.Database
{
/// <summary>
/// A typed store which supports basic addition, deletion and updating for soft-deletable models.
/// </summary>
/// <typeparam name="T">The databased model.</typeparam>
public abstract class MutableDatabaseBackedStore<T> : DatabaseBackedStore
where T : class, IHasPrimaryKey, ISoftDelete
{
public event Action<T> ItemAdded;
public event Action<T> ItemRemoved;
protected MutableDatabaseBackedStore(IDatabaseContextFactory contextFactory, Storage storage = null)
: base(contextFactory, storage)
{
}
/// <summary>
/// Access items pre-populated with includes for consumption.
/// </summary>
public IQueryable<T> ConsumableItems => AddIncludesForConsumption(ContextFactory.Get().Set<T>());
/// <summary>
/// Add a <typeparamref name="T"/> to the database.
/// </summary>
/// <param name="item">The item to add.</param>
public void Add(T item)
{
using (var usage = ContextFactory.GetForWrite())
{
var context = usage.Context;
context.Attach(item);
}
ItemAdded?.Invoke(item);
}
/// <summary>
/// Update a <typeparamref name="T"/> in the database.
/// </summary>
/// <param name="item">The item to update.</param>
public void Update(T item)
{
using (var usage = ContextFactory.GetForWrite())
usage.Context.Update(item);
ItemRemoved?.Invoke(item);
ItemAdded?.Invoke(item);
}
/// <summary>
/// Delete a <typeparamref name="T"/> from the database.
/// </summary>
/// <param name="item">The item to delete.</param>
public bool Delete(T item)
{
using (ContextFactory.GetForWrite())
{
Refresh(ref item);
if (item.DeletePending) return false;
item.DeletePending = true;
}
ItemRemoved?.Invoke(item);
return true;
}
/// <summary>
/// Restore a <typeparamref name="T"/> from a deleted state.
/// </summary>
/// <param name="item">The item to undelete.</param>
public bool Undelete(T item)
{
using (ContextFactory.GetForWrite())
{
Refresh(ref item, ConsumableItems);
if (!item.DeletePending) return false;
item.DeletePending = false;
}
ItemAdded?.Invoke(item);
return true;
}
/// <summary>
/// Allow implementations to add database-side includes or constraints when querying for consumption of items.
/// </summary>
/// <param name="query">The input query.</param>
/// <returns>A potentially modified output query.</returns>
protected virtual IQueryable<T> AddIncludesForConsumption(IQueryable<T> query) => query;
/// <summary>
/// Allow implementations to add database-side includes or constraints when deleting items.
/// Included properties could then be subsequently deleted by overriding <see cref="Purge"/>.
/// </summary>
/// <param name="query">The input query.</param>
/// <returns>A potentially modified output query.</returns>
protected virtual IQueryable<T> AddIncludesForDeletion(IQueryable<T> query) => query;
/// <summary>
/// Called when removing an item completely from the database.
/// </summary>
/// <param name="items">The items to be purged.</param>
/// <param name="context">The write context which can be used to perform subsequent deletions.</param>
protected virtual void Purge(List<T> items, OsuDbContext context) => context.RemoveRange(items);
public override void Cleanup()
{
base.Cleanup();
PurgeDeletable();
}
/// <summary>
/// Purge items in a pending delete state.
/// </summary>
/// <param name="query">An optional query limiting the scope of the purge.</param>
public void PurgeDeletable(Expression<Func<T, bool>> query = null)
{
using (var usage = ContextFactory.GetForWrite())
{
var context = usage.Context;
var lookup = context.Set<T>().Where(s => s.DeletePending);
if (query != null) lookup = lookup.Where(query);
lookup = AddIncludesForDeletion(lookup);
var purgeable = lookup.ToList();
if (!purgeable.Any()) return;
Purge(purgeable, context);
}
}
}
}