Template method example

In a project I work on, I need to programmatically fill out some PDF forms. The forms are very similar in terms of structure, content, and fields’ names. Using iTextSharp library, I can go through the fields in the PDF and set the values. The logic for filling out a PDF form can be generic, as I just need to know what are the fields’ names and the corresponding values of the PDF. I come up with a generic model and common logic for filing out the form, as demonstrated in the below snippets.

public abstract class PDFService<T> where T : class {
   
   public abstract IDictionary<string, PdfFormFieldModel> ToFormDict(T formModel);


   public virtual Stream FillPdf(PDFForm<T> formFillingRequest)
        {
           // ...codes omitted for brevity. 

                foreach (KeyValuePair<string, PdfFormFieldModel> entry in ToFormDict(formFillingRequest.Content as T))
                {
                    // use iTextSharp to loop through the fields and set the corresponding values. 
                }
        }
}

The PdfFormFieldModel is just a POCO to encapsulate a field in a PDF.

public class PdfFormFieldModel
    {
        public bool IsVisible { get; set; }
        public string Name { get; set; }
        public FieldType Type { get; set; }

        public string Value { get; set; }

        public PdfFormFieldModel(string fieldName)
        {
            Name = fieldName;
        }

        public PdfFormFieldModel(string fieldName, FieldType fieldType)
        {
            Name = fieldName;
            Type =…