Pre-validations in Dynamics 365 CE: JavaScript vs Plugins

When working with Dynamics 365 Customer Engagement (CE), ensuring data integrity before records are saved is critical. Pre-validations help achieve this, but the choice between JavaScript (client-side) and Plugins (server-side) can be tricky.

So, when should you use JavaScript validations on forms versus server-side plugins in the Pre-Operation stage? Let’s break it down.

JavaScript Validations (Client-Side)

When to Use

• Immediate feedback for end users.
• Validations based on form-level data.
• Dynamic field visibility, error notifications, or mandatory field checks.
• Business rules that change frequently and are UI-driven.

Pros

• Instant user experience (no server round-trip).
• Easy to implement using form events (onChange, onSave).
• Interactive guidance (e.g., show/hide fields, notifications).

Cons

• Bypassed if records are updated via API, integrations, or mobile apps.
• Browser-dependent; not foolproof for critical validations.
• Complex logic in JavaScript can be hard to maintain.

Example

if (formContext.getAttribute("revenue").getValue() < 0) {
    formContext.ui.setFormNotification("Revenue cannot be negative", "ERROR", "revenueValidation");
    executionContext.getEventArgs().preventDefault();
}

Plugins for Pre-Validation (Server-Side)

When to Use

• Enforcing business rules universally, regardless of the interface.
• Critical validations where data integrity is non-negotiable.
• Scenarios involving cross-entity validation or data lookups.

Pros

• Cannot be bypassed (applies to UI, API, integrations, and imports).
• Centralized, reusable, and version-controlled.
• More powerful (can query Dataverse, handle complex logic).

Cons

• No immediate UI feedback; errors appear only after a save attempt.
• Slightly longer round-trip time.
• Requires deployment via solutions.

Example

public void Execute(IServiceProvider serviceProvider)
{
    var context = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));
    var target = (Entity)context.InputParameters["Target"];

    if (target.Contains("revenue") && (decimal)target["revenue"] < 0)
    {
        throw new InvalidPluginExecutionException("Revenue cannot be negative.");
    }
}

When to Use Both?

For the best user experience and data integrity, combine them:

1. JavaScript: Provide user-friendly, instant feedback.
2. Plugin Pre-Validation: Ensure integrity across all channels.

Quick Decision Flow

Conclusion

• JavaScript: UX-friendly but limited in scope.
• Plugins: Robust and backend-safe but slower for feedback.
• Best Practice: Use JavaScript for soft validations and Plugins for enforcement.