/// <summary>
/// Creates a new instance of <see cref="DataLoaderState"/>.
/// </summary>
/// <param name="isEmpty">The flag indicating whether the <see cref="DataLoaderState"/> is empty.</param>
/// <returns><see cref="DataLoaderState"/></returns>
public DataLoaderState WithIsEmpty(bool isEmpty)
{
var newState = new DataLoaderState(this)
{
IsEmpty = isEmpty
};
return(newState);
}
/// <summary>
/// Creates a new instance of <see cref="DataLoaderState"/>.
/// </summary>
/// <param name="data">The data to populate the <see cref="DataLoaderState"/>.</param>
/// <returns><see cref="DataLoaderState"/></returns>
public DataLoaderState WithData(object data)
{
var newState = new DataLoaderState(this)
{
Data = data,
IsInitial = false
};
return(newState);
}
private int _sequenceId = -1; // This field is used to generate the SequenceId of each IDataLoaderRequest.
public DataLoader(string name, IDataLoaderStrategy strategy, DataLoaderConcurrentMode concurrentMode, Func <IDataLoaderState, bool> emptySelector)
{
Name = name ?? throw new ArgumentNullException(nameof(name));
_concurrentMode = concurrentMode;
_emptySelector = emptySelector ?? throw new ArgumentNullException(nameof(emptySelector));
_strategy = strategy ?? throw new ArgumentNullException(nameof(strategy));
_state = DataLoaderState.Default;
_triggers = new List <IDataLoaderTrigger>();
_contextValues = new Dictionary <string, object>();
_logger = this.Log();
}
private void UpdateState(Func <DataLoaderState, DataLoaderState> update)
{
var previousState = _state;
_state = update(_state);
_state = _state.WithIsEmpty(_emptySelector(_state));
if (!Equals(previousState, _state))
{
StateChanged?.Invoke(this, _state);
}
else
{
if (_logger.IsEnabled(LogLevel.Trace))
{
_logger.LogTrace($"Discarded state changed event because the new state is equal to the previous.");
}
}
}