从HTML创建PDF时出错 [英] Error Creating PDF from HTML

问题描述

嗨专家，

在.aspx页面我在面板中有asp.Panel，有一个从DB生成的转发器。

点击按钮我将html转换为PDF哪个工作得很好。

当我尝试在Page_Load上做同样的事情时，它给了我错误：

Hi Experts,
In .aspx page I have asp.Panel inside the panel there's a repeater generated from DB.
On button click I convert the html to PDF Which work very well.
When I try to do the same on Page_Load it gives me error:

The document has no pages.

尝试通过添加以下内容来解决此问题：

Tried to fix this by adding:

Document.Add(new Paragraph("Hello World!"));.

但是它给出了空的PDF文件。

所以我试图在页面加载后运行我的转换函数：

but it gives empty PDF file.
So I tried to run my converting function after page load:

protected override void Render(System.Web.UI.HtmlTextWriter writer)
        {
            base.Render(writer);
            Response.Flush();
            ExportPDF();
        }

它给出错误：

It gives error:

Server cannot set content type after HTTP headers have been sent

转换功能：

The converting function:

private void ExportPDF()
        {
            Response.ContentType = "application/pdf";
            Response.AddHeader("content-disposition", "attachment;filename=Invoice.pdf");
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            StringWriter sw = new StringWriter();
            HtmlTextWriter hw = new HtmlTextWriter(sw);
            pnlContents.RenderControl(hw); //the containing panel
            StringReader sr = new StringReader(sw.ToString());
            Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);

            HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
            PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
            pdfDoc.Open();
            htmlparser.Parse(sr);
            pdfDoc.Close();
            Response.Write(pdfDoc);
            Response.End();
        }

所以看起来asp.Panel有问题。

请告知为什么它可以按下按钮点击但是不在页面加载或渲染。我缺少什么？



感谢您的帮助

Samira

So It looks like something wrong with the asp.Panel.
Please advise why it would work on button click but not on page load or Render. What I am missing?

Thanks for help
Samira

推荐答案

发现了问题。必须像下面的代码一样设置渲染事件：

Found the problem. Had to set Render event like the following code:

protected override void Render(System.Web.UI.HtmlTextWriter writer)
        {
            ExportPDF();
            //base.Render(writer);
            //Response.Flush();            
        }

希望能帮到别人。



谢谢，

Samira

Hope will help others.

Thanks,
Samira

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