Read PDF interactive form fields in C# and VB.NET

The following example demonstrates how you can enumerate all interactive form fields and read their name, type, and value. In GemBox.Pdf, interactive form is represented with PdfInteractiveForm class and all field types share the same PdfField base class.

C#
VB.NET

View on GitHub

using System;
using GemBox.Pdf;
using GemBox.Pdf.Forms;

class Program
{
    static void Main()
    {
        // If using the Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        using (var document = PdfDocument.Load("%InputFileName%"))
        {
            Console.WriteLine(" Field Name      | Field Type      | Field Value ");
            Console.WriteLine(new string('-', 50));

            foreach (var field in document.Form.Fields)
            {
                string value = (field.Value ?? string.Empty).ToString().Replace("\r", ", ");
                Console.WriteLine($" {field.Name,-15} | {field.FieldType,-15} | {value}");
            }
        }
    }
}

Imports System
Imports GemBox.Pdf
Imports GemBox.Pdf.Forms

Module Program

    Sub Main()

        ' If using the Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY")

        Using document = PdfDocument.Load("%InputFileName%")
            Console.WriteLine(" Field Name      | Field Type      | Field Value ")
            Console.WriteLine(New String("-"c, 50))

            For Each field In document.Form.Fields
                Dim value As String = (If(field.Value, String.Empty)).ToString().Replace(vbCr, ", ")
                Console.WriteLine($" {field.Name} | {field.FieldType} | {value}")
            Next
        End Using

    End Sub

End Module

Screenshot of PDF interactive form fields read with GemBox.Pdf

Note that multiple PdfField instances can have the same name which means that these fields are grouped and represent the same interactive form field. The most common case is for PdfRadioButtonField, each radio button of the same name represents a different value you can select within one interactive form field.

The following shows how you can read additional field properties in a PDF document and how to read exportable values or choices for fields with the same name.

C#
VB.NET

View on GitHub

using System;
using GemBox.Pdf;
using GemBox.Pdf.Forms;

class Program
{
    static void Main()
    {
        // If using the Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        using (var document = PdfDocument.Load("%#FormFilled.pdf%"))
        {
            Console.WriteLine(" Field Name                         | Field Data ");
            Console.WriteLine(new string('-', 50));

            foreach (var field in document.Form.Fields)
            {
                switch (field.FieldType)
                {
                    case PdfFieldType.RadioButton:
                        var radioButton = (PdfRadioButtonField)field;
                        Console.Write($" {radioButton.Name,12} [PdfRadioButtonField] | ");
                        Console.WriteLine($"{radioButton.Choice} [{(radioButton.Checked ? "Checked" : "Unchecked")}]");
                        break;

                    case PdfFieldType.CheckBox:
                        var checkBox = (PdfCheckBoxField)field;
                        Console.Write($" {checkBox.Name,15} [PdfCheckBoxField] | ");
                        Console.WriteLine($"{checkBox.ExportValue} [{(checkBox.Checked ? "Checked" : "Unchecked")}]");
                        break;

                    case PdfFieldType.Dropdown:
                        var dropdown = (PdfDropdownField)field;
                        Console.Write($" {dropdown.Name,15} [PdfDropdownField] | ");
                        Console.WriteLine(dropdown.SelectedItem);
                        break;

                    case PdfFieldType.ListBox:
                        var listBox = (PdfListBoxField)field;
                        Console.Write($" {listBox.Name,16} [PdfListBoxField] | ");
                        Console.WriteLine(string.Join(", ", listBox.SelectedItems));
                        break;
                }
            }
        }
    }
}

Imports System
Imports GemBox.Pdf
Imports GemBox.Pdf.Forms

Module Program

    Sub Main()

        ' If using the Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY")

        Using document = PdfDocument.Load("%#FormFilled.pdf%")
            Console.WriteLine(" Field Name                         | Field Data ")
            Console.WriteLine(New String("-"c, 50))

            For Each field In document.Form.Fields

                Select Case field.FieldType

                    Case PdfFieldType.RadioButton
                        Dim radioButton = CType(field, PdfRadioButtonField)
                        Console.Write($" {radioButton.Name,12} [PdfRadioButtonField] | ")
                        Console.WriteLine($"{radioButton.Choice} [{If(radioButton.Checked, "Checked", "Unchecked")}]")

                    Case PdfFieldType.CheckBox
                        Dim checkBox = CType(field, PdfCheckBoxField)
                        Console.Write($" {checkBox.Name,15} [PdfCheckBoxField] | ")
                        Console.WriteLine($"{checkBox.ExportValue} [{If(checkBox.Checked, "Checked", "Unchecked")}]")

                    Case PdfFieldType.Dropdown
                        Dim dropdown = CType(field, PdfDropdownField)
                        Console.Write($" {dropdown.Name,15} [PdfDropdownField] | ")
                        Console.WriteLine(dropdown.SelectedItem)

                    Case PdfFieldType.ListBox
                        Dim listBox = CType(field, PdfListBoxField)
                        Console.Write($" {listBox.Name,16} [PdfListBoxField] | ")
                        Console.WriteLine(String.Join(", ", listBox.SelectedItems))

                End Select

            Next
        End Using

    End Sub
End Module

Toggle button fields and choice fields read with GemBox.Pdf — Screenshot of other properties in toggle button fields and choice fields

Next steps

GemBox.Pdf is a .NET component that enables developers to read, merge and split PDF files or execute low-level object manipulations from .NET applications in a simple and efficient way.

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Published: February 19, 2019 | Modified: July 6, 2023 | Author: Stipo Rubić

Read PDF interactive form fields in C# and VB.NET

See also

Next steps