Trying to alter links in PDF, but can only set not get Url

[DarthSonic]

According to docs, several examples and forum posts I added the following code to my project:

Code: Select all

            using var doc = new PdfDocument();

            doc.LoadFromFile(docPath);

            foreach (PdfPageBase page in doc.Pages)
            {
                foreach(PdfTextWebLinkAnnotationWidget link in page.AnnotationsWidget)
                {
                    var linkUrl = link.Url;

                    linkUrl.AddQueryParam("refId", model.Meta.ReferrerId ?? refId)
                           .SetQueryParam("utm_campaign", "referral")
                           .SetQueryParam("utm_source", "handout01")
                           .SetQueryParam("utm_medium", "pdf");

                    link.Url = linkUrl;
                }
            }


On line with getting current value of link.Url I get a System.NullReferenceException. I can not read the property. If I try only to set the link.Url to "google_com" all links in the PDF will get updated to that value.

Why can't I read the link.Url property? How to alter the current link? I habe to take current value and add some query parameters to it.

Thanks and regards,
Sven

[Brian.Li]

Hello Sven,

Thanks for your inquiry.
Please refer to the following code to get the link and alter the current link. If there are still any issues, please provide your PDF file for further investigation.

Code: Select all

            PdfDocument doc = new PdfDocument();
            doc.LoadFromFile("LinkAnnotation.pdf");

            List<string> links = new List<string>();
            foreach (PdfPageBase page in doc.Pages)
            {
                PdfAnnotationCollection pdfAnnotations = page.AnnotationsWidget;

                foreach (PdfAnnotation pdfAnnotation in pdfAnnotations)
                {
                    if (pdfAnnotation is PdfTextWebLinkAnnotationWidget)
                    {
                        PdfTextWebLinkAnnotationWidget link = pdfAnnotation as PdfTextWebLinkAnnotationWidget;
                        links.Add(link.Url);
                        link.Url = "http://www.e-iceblue.com";// alter the current link
                    }
                    else if (pdfAnnotation is PdfUriAnnotationWidget)
                    {
                        PdfUriAnnotationWidget link = pdfAnnotation as PdfUriAnnotationWidget;
                        links.Add(link.Uri);
                        link.Uri = "http://www.e-iceblue.com";// alter the current link
                    }
                }
            }
            doc.SaveToFile("result.pdf");

Sincerely,
Brian
E-iceblue support team