// Protected methods
protected virtual async Task ProcessBatchAsync(List <BatchItem <TKey, TEntity> > batch, CancellationToken cancellationToken)
{
await using var dbContext = CreateDbContext();
var keys = new HashSet <TKey>();
foreach (var item in batch)
{
if (!item.TryCancel(cancellationToken))
{
keys.Add(item.Input);
}
}
var pEntity = Expression.Parameter(typeof(TEntity), "e");
var eKey = KeyExtractorExpressionBuilder.Invoke(pEntity);
var eBody = Expression.Call(Expression.Constant(keys), ContainsMethod, eKey);
var eLambda = (Expression <Func <TEntity, bool> >)Expression.Lambda(eBody, pEntity);
var entities = await dbContext.Set <TEntity>()
.Where(eLambda)
.ToDictionaryAsync(KeyExtractor, cancellationToken)
.ConfigureAwait(false);
foreach (var item in batch)
{
entities.TryGetValue(item.Input, out var entity);
item.SetResult(Result.Value(entity) !, CancellationToken.None);
}
}
public DbEntityResolver(Options?options, IServiceProvider services) : base(services)
{
options ??= new();
BatchProcessorFactory = options.BatchProcessorFactory ??
(self => new AsyncBatchProcessor <TKey, TEntity> {
MaxBatchSize = 16,
ConcurrencyLevel = Math.Min(HardwareInfo.ProcessorCount, 4),
BatchingDelayTaskFactory = cancellationToken => Task.Delay(1, cancellationToken),
BatchProcessor = self.ProcessBatch,
});
_batchProcessorLazy = new Lazy <AsyncBatchProcessor <TKey, TEntity> >(
() => BatchProcessorFactory.Invoke(this));
using var dbContext = CreateDbContext();
var entityType = dbContext.Model.FindEntityType(typeof(TEntity));
var key = entityType.FindPrimaryKey();
KeyExtractorExpressionBuilder = options.KeyExtractorExpressionBuilder ??
(eEntity => Expression.PropertyOrField(eEntity, key.Properties.Single().Name));
var pEntity = Expression.Parameter(typeof(TEntity), "e");
var eBody = KeyExtractorExpressionBuilder.Invoke(pEntity);
KeyExtractor = (Func <TEntity, TKey>)Expression.Lambda(eBody, pEntity).Compile();
QueryTransformer = options.QueryTransformer ?? (q => q);
PostProcessor = options.PostProcessor ?? (_ => {});
}
