博客原文：https://demystifyingcrm.wordpress.com/2014/12/17/trigger-plugin-for-nn-relationships-in-dynamics-crm/

wordpress在国内访问有点困难，怎么访问作为技术的你应该懂的

下面分享个我的示例，有助于你的理解，parameters总共有3个，Relationship(用来表示当前n:n关系的关系名称，见下面截图)，Target和RelatedEntities分别对应的是两个实体，具体的还是看下面的代码就好

 public void Execute(IServiceProvider serviceProvider)

        {

            IPluginExecutionContext context = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));

            IOrganizationServiceFactory factory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));

            IOrganizationService service = factory.CreateOrganizationService(context.UserId);

            if (context.MessageName == "Associate")

            {

                if (context.Depth > 1)

                {

                    return;

                }

                Relationship entityRelationShip = (Relationship)context.InputParameters["Relationship"];

                if (entityRelationShip.SchemaName == "ubg_branch_product")//产品与分公司N:N的关联

                {

                    EntityReferenceCollection RelatedEntity = (EntityReferenceCollection)context.InputParameters["RelatedEntities"];

                    Entity product = service.Retrieve(RelatedEntity[0].LogicalName, RelatedEntity[0].Id, new ColumnSet("ubg_approvestate"));

                    if (product.Attributes.Contains("ubg_approvestate") && ((OptionSetValue)product["ubg_approvestate"]).Value != 1)

                    {

                        throw new InvalidPluginExecutionException("非草稿状态的产品不允许关联分公司!");

                    }

                }

                if (entityRelationShip.SchemaName == "ubg_product_ubg_datalist")//产品与资料列表N:N的关联

                {

                    EntityReference TargetEntity = (EntityReference)context.InputParameters["Target"];

                    Entity product = service.Retrieve(TargetEntity.LogicalName, TargetEntity.Id, new ColumnSet("ubg_approvestate"));

                    if (product.Attributes.Contains("ubg_approvestate") && ((OptionSetValue)product["ubg_approvestate"]).Value != 1)

                    {

                        throw new InvalidPluginExecutionException("非草稿状态的产品不允许资料!");

                    }

                }

            }

        }

为了方便那些确实没办法访问wordpress的，我这里把注册的图也给贴出来