Question

I am working on a CRM Dynamics Plugin. There is a field on custom entity named “email”. I want to make sure that for two entity records email addresses should be unique. For that purpose I have written following code:

public class Class1 : IPlugin
{
    public void Execute(IServiceProvider serviceProvider)
    {
        // Obtain the execution context from the service provider.
        Microsoft.Xrm.Sdk.IPluginExecutionContext context = (Microsoft.Xrm.Sdk.IPluginExecutionContext)
            serviceProvider.GetService(typeof(Microsoft.Xrm.Sdk.IPluginExecutionContext));

        // Get a reference to the organization service.
        IOrganizationServiceFactory factory =
        (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
        IOrganizationService service = factory.CreateOrganizationService(context.UserId);


        // The InputParameters collection contains all the data passed in the message request.
        if (context.InputParameters.Contains("Target") &&
            context.InputParameters["Target"] is Entity)
        {
            Entity entity = (Entity)context.InputParameters["Target"];

            //</snippetAccountNumberPlugin2>

            // Verify that the target entity represents an account.
            // If not, this plug-in was not registered correctly.
            if (context.MessageName.ToUpper() == "CREATE")
            {
                if (entity.LogicalName == "new_assignment1entity")
                {
                    try
                    {
                        QueryExpression query = new QueryExpression("new_assignment1entity");
                        query.ColumnSet.AddColumns("new_email");
                        EntityCollection result1 = service.RetrieveMultiple(query);
                        foreach (var a in result1.Entities)
                        {
                            int size = result1.Entities.Count;
                            if (a.Attributes["new_email"].ToString().Equals(entity["new_email"]))
                                throw new InvalidPluginExecutionException("Duplicate Email found!");
                        }
                    }
                    catch (FaultException<Microsoft.Xrm.Sdk.OrganizationServiceFault>)
                    {
                        //You can handle an exception here or pass it back to the calling method.
                        throw new InvalidPluginExecutionException("Some problem occurred while Querying Records!");
                    }
                }
            }
            else if (context.MessageName.ToUpper() == "UPDATE")
            {
                if (entity.LogicalName == "new_assignment1entity")
                {
                    try
                    {
                        QueryExpression query = new QueryExpression("new_assignment1entity");
                        query.ColumnSet.AddColumns("new_email");
                        EntityCollection result1 = service.RetrieveMultiple(query);
                        foreach (var a in result1.Entities)
                        {
                            int size = result1.Entities.Count;
                            if (a.Attributes["new_email"].ToString().Equals(entity["new_email"]))
                                throw new InvalidPluginExecutionException("Duplicate Email found!");
                        }
                    }
                    catch (FaultException<Microsoft.Xrm.Sdk.OrganizationServiceFault>)
                    {
                        //You can handle an exception here or pass it back to the calling method.
                        throw new InvalidPluginExecutionException("Some problem occurred while Querying Records!");
                    }
                }
            }
        }
    }
}

When User creates a new entity record with duplicate email address this code works and shows a dialog box printing error message. But when User edit an existing record (update and existing record) and makes the email address duplicate then this code does not work and updated record with duplicated email address saved.
I am guessing that Context message with UPDATE else part is not working.
Please help me out.

Answer 1

I resolved this issue. The problem why only Create execution flow was running and not Update is that I had only registered the plugin for create message step. To overcome this issue, I added a new step in same plugin and registered it with update message as show in following screenshot:

And it worked like charm.

Apart from this, @GregOwens mentioned very helpful points.These should follow as best practices in CRM Development.