Add custom business logic

What you will build

A validation hook on the Opportunity entity that runs before every insert and update.

Architecture

1. Entity
2. C# Hook
3. Validation

Steps

1. 1Create the script

   In Studio add a C# script bound to the Opportunity entity, with the Validate phase and the create and update operations. The class implements IValidationHook; the platform calls ValidateAsync by name.

2. 2Write the rule

   Every message you add to context.Errors refuses the save and is shown to the user.

   DiscountRule.csCopy

   using TAF.Infra.QueryHook.Interfaces;
   using TAF.Infra.QueryHook.Models;
   
   public class DiscountRule : IValidationHook
   {
       public Task ValidateAsync(HookContext context)
       {
           if (context.Fields.TryGetValue("DiscountPercent", out var value)
               && Convert.ToDecimal(value) > 20
               && !context.Fields.ContainsKey("ApprovalRequest"))
           {
               context.Errors.Add("Discounts above 20% need an approval request.");
           }
           return Task.CompletedTask;
       }
   }

3. 3Check it

   Run Check Script. Studio sends the code to the platform compiler and marks any errors in the editor. A validation hook that does not compile would block every save on the entity, so always check first.

4. 4Publish and test

   Publish the script, then save an opportunity with a 25% discount. The save is refused with your message. Hooks are compiled on first use and cached.

Result

A server-side rule that applies to every screen, API call, workflow and TAFI change that writes an opportunity.