/// <summary>
/// 解析持久化模型。
/// </summary>
/// <param name="dbContextAccessor">给定的数据库上下文访问器。</param>
/// <returns>返回 <see cref="IModel"/>。</returns>
protected virtual IModel ResolvePersistentModel
(DataDbContextAccessor <TAudit, TAuditProperty, TMigration, TTabulation, TTenant, TGenId, TIncremId, TCreatedBy> dbContextAccessor)
{
return(ExtensionSettings.Preference.RunLocker(() =>
{
var cacheKey = DbContextAccessorHelper.GetMigrationCacheKey(dbContextAccessor);
return MemoryCache.GetOrCreate(cacheKey, entry =>
{
Type snapshotType = null;
// 启用写入分离后，数据库可能会主从同步，因此尝试从数据库获取迁移数据不作连接限制
var lastMigration = dbContextAccessor.Migrations
.FirstOrDefaultByMax(s => s.CreatedTimeTicks);
if (lastMigration.IsNotNull())
{
var buffer = ModelSnapshotCompiler.RestoreAssembly(lastMigration.ModelBody);
var modelAssembly = Assembly.Load(buffer);
snapshotType = modelAssembly.GetType(lastMigration.ModelSnapshotName,
throwOnError: true, ignoreCase: false);
}
if (snapshotType.IsNotNull())
{
return snapshotType.EnsureCreate <ModelSnapshot>().Model;
}
return null;
});
}));
}
protected virtual void AddMigration
(DataDbContextAccessor <TAudit, TAuditProperty, TMigration, TTabulation, TTenant, TGenId, TIncremId, TCreatedBy> dbContextAccessor)
{
if (!dbContextAccessor.IsWritingConnectionString())
{
return;
}
(var body, var hash) = CreateModelSnapshot(dbContextAccessor, out var typeName);
dbContextAccessor.MigrationsManager.TryAdd(p => p.ModelHash == hash,
() =>
{
var identifierGenerator = (IDataStoreIdentificationGenerator <TGenId>)dbContextAccessor
.GetService <IStoreIdentificationGenerator>();
var migration = ObjectExtensions.EnsureCreate <TMigration>();
migration.Id = identifierGenerator.GenerateMigrationId();
migration.PopulateCreation(identifierGenerator.Clock);
migration.AccessorName = dbContextAccessor.CurrentType.GetDisplayNameWithNamespace();
migration.ModelSnapshotName = typeName;
migration.ModelBody = body;
migration.ModelHash = hash;
return(migration);
},
addedPost =>
{
if (!dbContextAccessor.RequiredSaveChanges)
{
dbContextAccessor.RequiredSaveChanges = true;
}
// 移除当前缓存
var cacheKey = DbContextAccessorHelper.GetMigrationCacheKey(dbContextAccessor);
MemoryCache.Remove(cacheKey);
// 发送迁移通知
var mediator = dbContextAccessor.GetService <IMediator>();
mediator.Publish(new MigrationNotification <TMigration>
{
Migration = addedPost.Entity
})
.ConfigureAwaitCompleted();
});
}