Dynamics 365 CE Update消息PostOperation阶段Image的尝试

我是微软Dynamics 365 & Power Platform方面的工程师罗勇，也是2015年7月到2018年6月连续三年Dynamics CRM/Business Solutions方面的微软最有价值专家(Microsoft MVP)，欢迎关注我的微信公众号 MSFTDynamics365erLuoYong ，回复355或者20190827可方便获取本文，同时可以在第一间得到我发布的最新博文信息，follow me!

前面的文章 Dynamics 365 CE在Pre Delete插件中应用Image 讲了Delete消息PreOperation阶段Image的应用，今天我们来看下Update 消息PostOperation阶段Image的尝试。

我使用如下代码简单注册一个插件：

using Microsoft.Xrm.Sdk;
using Microsoft.Xrm.Sdk.Query;
using System;
using System.ServiceModel;
using System.Text;

namespace CRM.Plugins
{
    public class PostWorkOrderUpdate : IPlugin
    {
        public void Execute(IServiceProvider serviceProvider)
        {
            ITracingService tracingService = (ITracingService)serviceProvider.GetService(typeof(ITracingService));
            IPluginExecutionContext context = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));
            if (context.InputParameters.Contains("Target") && context.InputParameters["Target"] is Entity)
            {
                Entity currentEntity = (Entity)context.InputParameters["Target"];
                IOrganizationServiceFactory serviceFactory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
                IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);
                Entity preImgEntity;
                Entity postImgEntity;
                Entity retrieveEntity;
                StringBuilder sb = new StringBuilder();
                try
                {
                    if (context.PreEntityImages.Contains("PreImg"))
                    {
                        preImgEntity = context.PreEntityImages["PreImg"];
                    }
                    else
                    {
                        throw new InvalidPluginExecutionException("Pre Update image - PreImg does not exist!");
                    }
                    if (context.PostEntityImages.Contains("PostImg"))
                    {
                        postImgEntity = context.PostEntityImages["PostImg"];
                    }
                    else
                    {
                        throw new InvalidPluginExecutionException("Post Update image - PostImg does not exist!");
                    }
                    retrieveEntity = service.Retrieve(currentEntity.LogicalName, currentEntity.Id, new ColumnSet("ly_singletext2", "ly_singletext3"));
                    if (retrieveEntity.Contains("ly_singletext2"))
                    {
                        sb.Append("retrieveEntity contains attribute ly_singletext2 = ");
                        sb.Append(retrieveEntity.GetAttributeValue<string>("ly_singletext2"));
                        sb.Append("; ");
                    }
                    else
                    {
                        sb.Append("retrieveEntity does not contain attribute ly_singletext2");
                        sb.Append("; ");
                    }
                    if (currentEntity.Contains("ly_singletext2"))
                    {
                        sb.Append("currentEntity contains attribute ly_singletext2 = ");
                        sb.Append(currentEntity.GetAttributeValue<string>("ly_singletext2"));
                        sb.Append("; ");
                    }
                    else
                    {
                        sb.Append("currentEntity does not contain attribute ly_singletext2");
                        sb.Append("; ");
                    }
                    if (preImgEntity.Contains("ly_singletext2"))
                    {
                        sb.Append("preImgEntity contains attribute ly_singletext2 = ");
                        sb.Append(preImgEntity.GetAttributeValue<string>("ly_singletext2"));
                        sb.Append("; ");
                    }
                    else
                    {
                        sb.Append("preImgEntity does not contain attribute ly_singletext2");
                        sb.Append("; ");
                    }
                    if (postImgEntity.Contains("ly_singletext2"))
                    {
                        sb.Append("postImgEntity contains attribute ly_singletext2 = ");
                        sb.Append(postImgEntity.GetAttributeValue<string>("ly_singletext2"));
                        sb.Append("; ");
                    }
                    else
                    {
                        sb.Append("postImgEntity does not contain attribute ly_singletext2");
                        sb.Append("; ");
                    }
                    if (retrieveEntity.Contains("ly_singletext3"))
                    {
                        sb.Append("retrieveEntity contains attribute ly_singletext3 = ");
                        sb.Append(retrieveEntity.GetAttributeValue<string>("ly_singletext3"));
                        sb.Append("; ");
                    }
                    else
                    {
                        sb.Append("retrieveEntity does not contain attribute ly_singletext3");
                        sb.Append("; ");
                    }
                    if (currentEntity.Contains("ly_singletext3"))
                    {
                        sb.Append("currentEntity contains attribute ly_singletext3 = ");
                        sb.Append(currentEntity.GetAttributeValue<string>("ly_singletext3"));
                        sb.Append("; ");
                    }
                    else
                    {
                        sb.Append("currentEntity does not contain attribute ly_singletext3");
                        sb.Append("; ");
                    }
                    if (preImgEntity.Contains("ly_singletext3"))
                    {
                        sb.Append("preImgEntity contains attribute ly_singletext3 = ");
                        sb.Append(preImgEntity.GetAttributeValue<string>("ly_singletext3"));
                        sb.Append("; ");
                    }
                    else
                    {
                        sb.Append("preImgEntity does not contain attribute ly_singletext3");
                        sb.Append("; ");
                    }
                    if (postImgEntity.Contains("ly_singletext3"))
                    {
                        sb.Append("postImgEntity contains attribute ly_singletext3 = ");
                        sb.Append(postImgEntity.GetAttributeValue<string>("ly_singletext3"));
                        sb.Append("; ");
                    }
                    else
                    {
                        sb.Append("postImgEntity does not contain attribute ly_singletext3");
                        sb.Append("; ");
                    }
                    throw new InvalidPluginExecutionException(sb.ToString());
                }
                catch (FaultException<OrganizationServiceFault> ex)
                {
                    throw new InvalidPluginExecutionException("An error occurred in PostWorkOrderUpdate.", ex);
                }
                catch (Exception ex)
                {
                    tracingService.Trace("PostWorkOrderUpdate unexpected exception: {0}", ex.Message);
                    throw;
                }
            }
        }
    }
}

插件注册信息如下：

我还为此Step注册了两个Image，一个为Pre阶段的Image，一个为Post阶段的Image，如下：

然后我进行了一系列测试：

如果两个字段都变化，获取到的消息如下：

retrieveEntity contains attribute ly_singletext2 = 5-New;
currentEntity contains attribute ly_singletext2 = 5-New;
preImgEntity contains attribute ly_singletext2 = 5;
postImgEntity contains attribute ly_singletext2 = 5-New;
retrieveEntity contains attribute ly_singletext3 = 总体满意度-New;
currentEntity contains attribute ly_singletext3 = 总体满意度-New;
preImgEntity contains attribute ly_singletext3 = 总体满意度;
postImgEntity contains attribute ly_singletext3 = 总体满意度-New;

如果只更改一个字段ly_singletext2的值，另外一个字段ly_singletext3不变，保存后获取的结果是：

retrieveEntity contains attribute ly_singletext2 = 5-New;
currentEntity contains attribute ly_singletext2 = 5-New;
preImgEntity contains attribute ly_singletext2 = 5;
postImgEntity contains attribute ly_singletext2 = 5-New;
retrieveEntity contains attribute ly_singletext3 = 总体满意度;
currentEntity does not contain attribute ly_singletext3;
preImgEntity contains attribute ly_singletext3 = 总体满意度;
postImgEntity contains attribute ly_singletext3 = 总体满意度;

如果只更改一个字段ly_singletext2的值，这里将其值清空，另外一个字段ly_singletext3不变，保存后获取的结果是：

retrieveEntity does not contain attribute ly_singletext2;
currentEntity contains attribute ly_singletext2 = ;
preImgEntity contains attribute ly_singletext2 = 5;
postImgEntity does not contain attribute ly_singletext2;
retrieveEntity contains attribute ly_singletext3 = 总体满意度;
currentEntity does not contain attribute ly_singletext3;
preImgEntity contains attribute ly_singletext3 = 总体满意度;
postImgEntity contains attribute ly_singletext3 = 总体满意度; 

如果只更改一个字段ly_singletext2的值，本来该字段的值为空，这里设置其值为New，另外一个字段ly_singletext3的值一直为空保持不变，保存后获取的结果是：

retrieveEntity contains attribute ly_singletext2 = New;
currentEntity contains attribute ly_singletext2 = New;
preImgEntity does not contain attribute ly_singletext2;
postImgEntity contains attribute ly_singletext2 = New;
retrieveEntity does not contain attribute ly_singletext3;
currentEntity does not contain attribute ly_singletext3;
preImgEntity does not contain attribute ly_singletext3;
postImgEntity does not contain attribute ly_singletext3; 

总结下：

• Target参数转换后的实体会包括所有要设置新值的字段(属性)，如果要设置的新值为空值，也会包括该字段(属性)，只是该字段(属性)的值为空。
• Target参数转换后的实体不会包括不更改的字段(属性)。
• Pre Update Image包括了字段更新之前的值，如果之前该字段的值为空值，则Pre Update Image不会包括这个字段(属性)；
• Post Update Image包括了字段(属性)要更新的值，如果字段(属性)是更新为空值则Post Update Image不包括该字段，如果字段(属性)不更新的话，Post Update Image包括的就是这个字段(属性)的原值；
• 在Post Update阶段查询当前实体的字段(属性)值，查询到的是要变更的新值，如果字段(属性)要要更新为空值，查询结果的字段(属性)集中不会包括该字段(属性)，所以不用再查询，直接从Target参数转换后的实体的字段(属性)集合中获取。
• 如果要看字段(属性)值在Update消息中是否变化的话，检查Target参数转换后的实体是否包括该字段(属性)即可，新值在Target参数转换后的实体的字段(属性)集合中，旧值可以用Pre Update Image来获取。
• 获取Image之前先检查Image是否存在，分别用类似context.PreEntityImages.Contains("PreImg") 或者 context.PostEntityImages.Contains("PostImg")。
• 获取字段(属性)值之前先检查字段(属性)的确存在，用类似 currentEntity.Contains("ly_singletext2") 的语法。