CQRS - 动态对象的映射命令

Question

我正在使用Azure函数的CQRS设计模式。我通过我的HttpTrigger Azure函数获得动态请求对象。现在，我已经根据请求中的 "EventType "属性来映射我的命令。

这是我的Azure函数。

[FunctionName("ReceiveEvent")]
        public static async Task<IActionResult> Run(
            [HttpTrigger(AuthorizationLevel.Function, "post", Route = null)] HttpRequest req,
            ILogger log)
        {
            log.LogInformation("ReceiveEvent HTTP trigger function started processing request.");

             log.LogInformation($"Pushing Events to Azure Blob on storage account :-{CloudConfigurationManager.GetSetting("AzureWebJobsStorage")}");

            IActionResult actionResult = null;

            string requestBody = await new StreamReader(req.Body).ReadToEndAsync();

            dynamic data = JsonConvert.DeserializeObject(requestBody);

            var eventType = EventType.Unknown;

            string eventTypeValue = data.EventType;
            Enum.TryParse(eventTypeValue, true, out eventType);



            switch (eventType)
            {
                case EventType.CARD_BLOCK:
                    command = _cardBlockCommandMapper.Map(data);
                    break;
                case EventType.CARD_CANCEL:
                    command = _cardCancelCommandMapper.Map(data);
                    break;


            }

            return actionResult;

这是我的命令映射器。

public class CardBlockCommandMapper : ICardBlockCommandMapper
    {
        public CardBlockCommand Map(dynamic data)
        {
            return new CardBlockCommand
            {
                Message = data.Message,
                ModifiedByName = data.ModifiedByName
            };
        }
    }

命令。

public abstract class Command
    {
        public virtual EventType EventType { get; set; }
    }

public class CardBlockCommand : Command
    {
        public override EventType EventType => EventType.CARD_BLOCK;
        public string ModifiedByName { get; set; }
        public string Message { get; set; }
    }
 public class CardCancelledCommand:Command
    {
        public override EventType EventType => EventType.CARD_CANCEL;
        public string Message { get; set; }
        public List<string> MetaData { get; set; }
    }

这是我的命令处理程序

public class CardBlockCommandHandler : ICommandHandler<CardBlockCommand>
    {
        private readonly IAzureBlobStorage _azureBlobStorage;

        public CardBlockCommandHandler(IAzureBlobStorage azureBlobStorage)
        {
            _azureBlobStorage = azureBlobStorage;
        }

        public void Handle(CardBlockCommand command)
        {
            try
            {
                //TODO: Store into blob
                //_azureBlobStorage.UploadMessageContentAsync(storageConnectionString: string.Empty,
                //    storageContainerName: string.Empty, blobName: string.Empty, content: string.Empty);

                throw new NotImplementedException();
            }
            catch
            {

            }
        }
    }

我的问题是，我总共有15种不同类型的事件类型。我是否需要为每个类型创建一个单独的命令映射器？或者有什么更好的方法吗？

Answer 1

正如@Jochem Van Hespen所提到的，最简单的方法是将json反序列化为基于Enum值的具体类型。

分析一下这段代码，看看对你来说是否是一个更好的解决方案。

using System;
using System.Collections.Generic;
using Newtonsoft.Json;

namespace TestAPI
{
    public abstract class Command
    {
        public virtual EventType EventType { get; set; }
    }

    public class CardBlockCommand : Command
    {
        public override EventType EventType => EventType.CARD_BLOCK;
        public string ModifiedByName { get; set; }
        public string Message { get; set; }
    }
    public class CardCancelledCommand : Command
    {
        public override EventType EventType => EventType.CARD_CANCEL;
        public string Message { get; set; }
        public List<string> MetaData { get; set; }
    }

    public enum EventType
    {
        CARD_BLOCK,
        CARD_CANCEL,
        Unknown
    }


    public class Program
    {

        public static void Main(string[] args)
        {

            var requestBody =
                @"{ eventType: ""CARD_BLOCK"", message: ""message"", modifiedByName: ""ModifiedByName""}";  // sample response (json) from request
            dynamic data = JsonConvert.DeserializeObject(requestBody);

            string eventTypeValue = data.EventType;
            Enum.TryParse(eventTypeValue, true, out EventType eventType);



            switch (eventType)
            {
                case EventType.CARD_BLOCK:
                    CardBlockCommand cardBlockCommand = JsonConvert.DeserializeObject<CardBlockCommand>(requestBody);
                    // handler.Handle(cardBlockCommand)
                    break;
                case EventType.CARD_CANCEL:
                    CardCancelledCommand cardCancelledCommand = JsonConvert.DeserializeObject<CardCancelledCommand>(requestBody);
                    // handler.Handle(cardCancelledCommand)
                    break;
            }

        }
    }
}