如何使用 SqlBulkCopy 編寫 IAsyncEnumerable

Question

我有以下方法返回IAsyncEnumerable<T> ：

async IAsyncEnumerable<T> RunReport()
{
    var handler = new HttpClientHandler();

    var client = new HttpClient(handler);
    client.BaseAddress = new Uri("");
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    var settings = new JsonSerializerSettings();

    var jsonFormatter = new JsonMediaTypeFormatter() { SerializerSettings = settings };

    var requestMessage = new HttpRequestMessage(HttpMethod.Get, "api/controler");
    var response = await client.SendAsync(requestMessage);

    response.EnsureSuccessStatusCode();

    using (var stream = await response.Content.ReadAsStreamAsync())
    {
        using (var reader = new StreamReader(stream))
        {
            while (!reader.EndOfStream)
            {
                var linesJson = await reader.ReadLineAsync();
                var line = JsonConvert.DeserializeObject<List<T>>(linesJson, jsonFormatter.SerializerSettings);

                foreach (var line in lines)
                    yield return line;
            }
        }
    }
}

我想使用SqlBulkCopy的WriteToServerAsync方法將該結果流傳輸到數據庫，但無法弄清楚如何將其轉換為IDataReader或WriteToServerAsync的重載列表中的任何其他類型。

如果性能合理，我願意使用批量復制以外的其他東西。

Answer 1

使用此處的示例，我想出了一個 IDataReader，它采用 IAsyncEnumerable，並實現接口的適當部分。

public class GenericDataReader<T> : IDataReader where T : class
{
    private readonly IAsyncEnumerator<T> _asychEnumerator;
    private readonly List<FieldInfo> _fields = new List<FieldInfo>();

    public GenericDataReader(IAsyncEnumerable<T> asyncEnumerable)
    {
        _asychEnumerator = asyncEnumerable.GetAsyncEnumerator();

        foreach (FieldInfo fieldinfo in typeof(T).GetFields(BindingFlags.Instance | BindingFlags.Public))
        {
            _fields.Add(fieldinfo);
        }
    }

    public int FieldCount => _fields.Count;

    public void Dispose() { Close(); }

    public bool Read()
    {
        return _asycEnumerator.MoveNextAsync().Result;
    }

    public async void Close(){ await _asychEnumerator.DisposeAsync(); }

    public Type GetFieldType(int i){ return _fields[i].FieldType; }

    public string GetName(int i) { return _fields[i].Name; }

    public object GetValue(int i){ return _fields[i].GetValue(_asychEnumerator.Current); }
}   

我仍在研究這個例子，但對 Read() 方法的實現有點了解。