nickmeron/skills/pac-plugin

The user wants to scaffold or build a Dynamics 365 plugin project.

Argument provided: $ARGUMENTS

Prerequisites

pac --version
dotnet --version   # .NET 6+ SDK required

Workflows

"Create a new plugin project"

pac plugin init --outputDirectory ./MyPlugin
cd ./MyPlugin
dotnet build

This scaffolds:

• .csproj with Microsoft.CrmSdk.CoreAssemblies reference
• Plugin1.cs — starter plugin class implementing IPlugin
• .snk — strong name key file for assembly signing

"Write a plugin class"

Standard pattern:

using Microsoft.Xrm.Sdk;
using System;

namespace MyPlugin
{
    public class PreCreateAccount : IPlugin
    {
        // Unsecure/Secure configuration from step registration
        private readonly string _unsecureConfig;
        private readonly string _secureConfig;

        public PreCreateAccount(string unsecureConfig, string secureConfig)
        {
            _unsecureConfig = unsecureConfig;
            _secureConfig = secureConfig;
        }

        public void Execute(IServiceProvider serviceProvider)
        {
            // Get context
            var context = (IPluginExecutionContext)serviceProvider
                .GetService(typeof(IPluginExecutionContext));

            // Get tracing service (writes to Plugin Trace Logs)
            var tracingService = (ITracingService)serviceProvider
                .GetService(typeof(ITracingService));

            // Get org service (for CRUD operations)
            var serviceFactory = (IOrganizationServiceFactory)serviceProvider
                .GetService(typeof(IOrganizationServiceFactory));
            var orgService = serviceFactory.CreateOrganizationService(context.UserId);

            try
            {
                tracingService.Trace("Plugin started for message: {0}", context.MessageName);

                if (context.InputParameters.Contains("Target")
                    && context.InputParameters["Target"] is Entity entity)
                {
                    // Your logic here
                    tracingService.Trace("Entity: {0}, Id: {1}", entity.LogicalName, entity.Id);
                }
            }
            catch (Exception ex)
            {
                tracingService.Trace("Error: {0}", ex.ToString());
                throw new InvalidPluginExecutionException(
                    $"An error occurred in {nameof(PreCreateAccount)}: {ex.Message}", ex);
            }
        }
    }
}

"Access pre/post images in plugin"

// Pre-image (entity state BEFORE the operation)
if (context.PreEntityImages.Contains("PreImage"))
{
    var preImage = context.PreEntityImages["PreImage"];
    var oldName = preImage.GetAttributeValue<string>("name");
}

// Post-image (entity state AFTER the operation)
if (context.PostEntityImages.Contains("PostImage"))
{
    var postImage = context.PostEntityImages["PostImage"];
    var newName = postImage.GetAttributeValue<string>("name");
}

"Build the DLL"

dotnet build -c Release

Output: bin/Release/net462/MyPlugin.dll (or netcoreapp3.1 for newer SDK)

"Sign the assembly with a certificate"

For managed identity or strong naming:

# With signtool (Windows SDK)
signtool sign /f certificate.pfx /p "password" /fd SHA256 bin/Release/net462/MyPlugin.dll

# Verify signature
signtool verify /pa bin/Release/net462/MyPlugin.dll

For strong naming only (included in pac plugin init):

# The .snk file is auto-generated by pac plugin init
# It's referenced in the .csproj:
# <SignAssembly>true</SignAssembly>
# <AssemblyOriginatorKeyFile>YourKey.snk</AssemblyOriginatorKeyFile>

"Register the plugin and steps"

After building, use the MCP tools:

1. Upload assembly manually via Plugin Registration Tool (the classic way) OR use pac plugin push for quick dev iteration:

   pac plugin push --assemblyPath bin/Release/net462/MyPlugin.dll
   

2. Register steps using MCP tools:

   • list_plugin_assemblies → find your assembly
   • list_plugin_types → find your class
   • list_sdk_messages → find "Create"/"Update"/etc
   • list_sdk_message_filters → find the entity filter
   • register_processing_step → register the step
   • register_step_image → add pre/post images

"Add NuGet packages to the plugin"

Common packages:

# Core SDK (already included)
dotnet add package Microsoft.CrmSdk.CoreAssemblies

# For early-bound classes
dotnet add package Microsoft.CrmSdk.CoreTools

# For workflow activities
dotnet add package Microsoft.CrmSdk.Workflow

# For managed identity (token acquisition)
dotnet add package Microsoft.PowerPlatform.Dataverse.Client

"Create early-bound entity classes"

# Using pac
pac modelbuilder build --outdirectory ./EarlyBound --entitynamesfilter "account;contact;opportunity"

# Or using CrmSvcUtil (classic)
CrmSvcUtil.exe /url:https://yourorg.crm.dynamics.com/XRMServices/2011/Organization.svc /out:EarlyBound.cs

Plugin project structure

MyPlugin/
├── MyPlugin.csproj          # Project file with SDK references
├── MyPlugin.snk             # Strong name key
├── Plugin1.cs               # Starter plugin class
├── PreCreateAccount.cs      # Your custom plugin
├── PostUpdateContact.cs     # Another plugin class
├── Helpers/
│   └── TraceHelper.cs       # Shared utilities
└── bin/
    └── Release/
        └── net462/
            └── MyPlugin.dll # Built assembly

Troubleshooting

• "Plugin type not found after upload" → Ensure the class is public and implements IPlugin
• "Assembly must be signed" → Check .csproj has <SignAssembly>true</SignAssembly> and .snk exists
• "Sandbox execution error" → Plugin runs in isolation mode; can't access local files or unrestricted network. Use IManagedIdentityService for external calls
• "Depth exceeded" → Plugin is triggering itself recursively. Check context.Depth and exit if > 1