How to inspect PDF push-button actions in C#

Enumerate push buttons

GetFieldsAsync() returns terminal fields. Use LINQ type filtering to find push buttons.

using ZingPDF;
using ZingPDF.Elements.Forms.FieldTypes.Button;

using var pdf = Pdf.Load(File.OpenRead("form.pdf"));

var form = await pdf.GetFormAsync();
if (form is null)
{
    return;
}

foreach (var button in (await form.GetFieldsAsync()).OfType())
{
    var caption = await button.GetCaptionAsync();
    Console.WriteLine($"{button.Name}: {caption}");
}

Read action metadata

A push button can expose a primary action dictionary. The high-level wrapper reports common action metadata without executing the action.

var button = await form.GetFieldAsync("Submit");
if (button is not null && await button.HasActionAsync())
{
    var actionType = await button.GetActionTypeAsync();
    var uri = await button.GetActionUriAsync();
    var namedAction = await button.GetNamedActionAsync();

    Console.WriteLine($"Action type: {actionType}");
    Console.WriteLine($"URI: {uri}");
    Console.WriteLine($"Named action: {namedAction}");
}

Additional actions

Additional-action dictionaries are keyed by trigger names such as mouse, focus, blur, or page-state events. ZingPDF reports the trigger keys present on the field or its widgets.

var button = await form.GetFieldAsync("Submit");
if (button is null)
{
    return;
}

var triggers = await button.GetAdditionalActionTriggersAsync();

foreach (var trigger in triggers)
{
    Console.WriteLine(trigger);
}

Scope

• GetCaptionAsync() reads the field or widget caption when present.
• GetActionTypeAsync() returns the primary action /S name.
• GetActionUriAsync() returns a target only for primary URI actions.
• GetNamedActionAsync() returns a value only for primary named actions.
• The library does not submit forms, open URLs, reset forms, or run JavaScript.

Next step

For ordinary field filling, see How to fill PDF form fields in C#.