How to Write and Understand a Dynamics CRM Plugin

 Here’s a sample plugin code in Dynamics CRM written in C#, along with a detailed explanation of each line. This plugin will update the "Description" field of an entity whenever a record is created.

Sample Plugin Code

using System;                           // For basic .NET types
using Microsoft.Xrm.Sdk;                // Provides key interfaces for CRM plugin development
using Microsoft.Xrm.Sdk.Query;          // For performing queries against CRM data

namespace SamplePluginNamespace           // Custom namespace for the plugin
{
    public class SamplePlugin : IPlugin  // Plugin class implementing the IPlugin interface
    {
        public void Execute(IServiceProvider serviceProvider)
        {
            // STEP 1: Retrieve the context of the plugin
            IPluginExecutionContext context = 
                (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));

            if (context.MessageName != "Create" || context.Stage != 40) 
                return;  // Exit if the message is not 'Create' or it is not in the 'PostOperation' stage

            // STEP 2: Obtain the organization service
            IOrganizationServiceFactory serviceFactory = 
                (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
            IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);

            // STEP 3: Retrieve the target entity from the input parameters
            Entity targetEntity = (Entity)context.InputParameters["Target"];

            try
            {
                // STEP 4: Update the 'Description' field with a custom message
                targetEntity["description"] = $"Record created on {DateTime.Now}";

                // STEP 5: Persist changes back to the database
                service.Update(targetEntity);
            }
            catch (Exception ex)
            {
                // STEP 6: Handle errors and rethrow as an InvalidPluginExecutionException
                throw new InvalidPluginExecutionException($"An error occurred in the SamplePlugin: {ex.Message}", ex);
            }
        }
    }
}

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Line-by-Line Explanation

1. using System;

   • Imports basic .NET library types such as DateTime and exceptions.

2. using Microsoft.Xrm.Sdk;

   • Imports CRM SDK interfaces for plugins such as IPlugin, IPluginExecutionContext, and IOrganizationService.

3. using Microsoft.Xrm.Sdk.Query;

   • Enables querying CRM entities when interacting with data.

4. namespace SamplePluginNamespace

   • Defines a custom namespace to organize the code logically and avoid naming conflicts.

5. public class SamplePlugin : IPlugin

   • Implements the IPlugin interface, making this class recognized by Dynamics CRM as a plugin.

6. public void Execute(IServiceProvider serviceProvider)

   • The main method executed when the plugin is triggered, as required by the IPlugin interface.

7. Retrieve plugin execution context:

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

   • Retrieves the execution context, which contains all information about the triggered event.

8. Validate event type and stage:

   if (context.MessageName != "Create" || context.Stage != 40) 
       return;
   

   • Ensures the plugin executes only for the Create message in the PostOperation stage.

9. Create organization service:

   IOrganizationServiceFactory serviceFactory = 
       (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
   IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);
   

   • Creates an organization service instance for interacting with CRM data.

10. Retrieve the target entity:

    Entity targetEntity = (Entity)context.InputParameters["Target"];
    

    • Extracts the target record being created.

11. Update the Description field:

    targetEntity["description"] = $"Record created on {DateTime.Now}";
    

    • Sets the Description field value dynamically based on the current date and time.

12. Persist changes to CRM:

    service.Update(targetEntity);
    

    • Updates the record in the database with the new value in the Description field.

13. Handle exceptions:

    catch (Exception ex)
    {
        throw new InvalidPluginExecutionException($"An error occurred in the SamplePlugin: {ex.Message}", ex);
    }
    

    • Catches runtime exceptions and throws them as InvalidPluginExecutionException for debugging or logging purposes.

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Usage Details

• Registration: Use the Plugin Registration Tool to register this plugin in CRM for the Create message.
• Target Entity: Ensure the target entity has a field named description. Adjust the field name accordingly if different.

This plugin demonstrates essential patterns like validation, service access, and error handling, ensuring robust development in Dynamics CRM.