Demo 22 - Build a plug-in

Objective: In this demo, you will show how to create a Dataverse plug-in to validate a Pet Trick record is associated with a Trick and a Pet.

Task 22.1 - Create plug-in

Create a folder on the Virtual machine named DemoPlugin and then run the following commands in the Developer command prompt.
```
  pac plugin init
```
```
  start DemoPlugin.csproj
```
Rename Plugin1.cs to ValidatePetTrick.cs.

Replace the code.

 using Microsoft.Xrm.Sdk;
 using System;
    
 namespace DemoPlugin
 {
     public class ValidatePetTrick : PluginBase
     {
         public ValidatePetTrick(string unsecureConfiguration, string secureConfiguration) : base(typeof(ValidatePetTrick))
         {
         }
    
         protected override void ExecuteDataversePlugin(ILocalPluginContext localPluginContext)
         {
             if (localPluginContext == null)
             {
                 throw new ArgumentNullException(nameof(localPluginContext));
             }
    
             var context = localPluginContext.PluginExecutionContext;
             localPluginContext.Trace("Message:" + context.MessageName);
             localPluginContext.Trace("Entity:" + context.PrimaryEntityName);
             localPluginContext.Trace("Primary Entity Id:" + context.PrimaryEntityId.ToString());
             localPluginContext.Trace("Stage:" + context.Stage.ToString());
             localPluginContext.Trace("Depth:" + context.Depth.ToString());
    
             // Validate Entity and Message
             if (context.PrimaryEntityName != "dem_pettrick")
             {
                 localPluginContext.Trace("Primary Entity is not Pet Trick");
                 //return;
             }
    
             if (context.MessageName.ToLower() != "create")
             {
                 localPluginContext.Trace("Message is not Create");
                 return;
             }
    
             // Validate contents of entity
             if (context.InputParameters.Contains("Target") && context.InputParameters["Target"] is Entity)
             {
                 localPluginContext.Trace("Target");
                 var entity = (Entity)context.InputParameters["Target"];
                 if (!entity.Contains("dem_petid"))
                 {
                     localPluginContext.Trace("No Pet in Entity");
                     throw new InvalidPluginExecutionException("A pet must be selected");
                 }
                 if (!entity.Contains("dem_trickid"))
                 {
                     localPluginContext.Trace("No Trick in Entity");
                     throw new InvalidPluginExecutionException("A trick must be selected");
                 }
             }
         }
     }
 }

Build the project.

Task 22.2 - Register plug-in

Start the Plug-in Registration Tool.
- In the command prompt, run the command below to launch the Plugin Registration Tool (PRT).
```
pac tool prt
```
Create a connection to the Demo environment.
Register the DemoPlugin.dll assembly.
Register a step on the DemoPlugin.dll assembly.
- Enter Create for Message.
- Enter dem_pettrick for Primary Table.
- Select PreValidation from dropdown for Event Pipeline Stage of Execution.

Task 22.3 - Test plug-in

Open a new Pet Trick form.
Enter a name and select Save.
Select a Pet and select Save.
Select a Trick and select Save.

Task 22.4 - Add plug-in to solution

In the demo solution, add existing Plug-in Assembly and select DemoPlugin.
In the demo solution, add existing Plug-in step and select Create of dem_pettrick.