PdfSharp，在 C# 错误中更新元数据

Question

I am using the PdfSharp reference library to attempt to add functionality to my program that adds metadata tags. I am able to successfully add metadata tags to a document, but I am having an issue with updating the tags on existing custom properties. Whenever I attempt to use my method to update the custom properties, I receive the following exception:

"'System.Collections.Generic.KeyValuePair' does not contain a definition for 'Name'."

Could you guys tell me if I am coding the if statement in the foreach loop below to correctly loop through all of the custom elements in the PDF document to see if it exists and needs to be updated? Thanks.

public void AddMetaDataPDF(string property, string propertyValue, string    
                                                                   path)
{
    PdfDocument document = PdfReader.Open(path);
    bool propertyFound = false;

    try {
           dynamic properties = document.Info.Elements;
           foreach(dynamic p in properties)
           {
               //Check to see if the property exists. If it does, update   
                   value.
               if(string.Equals(p.Name, property,  
                StringComparison.InvariantCultureIgnoreCase))
               {
                   document.Info.Elements.SetValue("/" + property, new   
                           PdfString(propertyValue));
               }
           }
           // the property doesn't exist so add it
           if(!propertyFound)
           {
               document.Info.Elements.Add(new KeyValuePair<String, PdfItem>   
                   ("/"+ property, new PdfString(propertyValue)));
           }
      }

      catch (Exception ex)
      {
          MessageBox.Show(path + "\n" + ex.Message);
          document.Close();

      }
      finally
      {
          if(document != null)
          {
              document.Save(path);
              document.Close();
          }
      }
}

Answer 1

I didn't try your code but a common issue when working with this library is that you need to add a slash before the name of the property for it to be found. The code below will make the trick.

PdfDocument document = PdfReader.Open(path);
var properties = document.Info.Elements;
if (properties.ContainsKey("/" + propertyName))
{
    properties.SetValue("/" + propertyName, new PdfString(propertyValue));
}
else
{
    properties.Add(new KeyValuePair<String, PdfItem>("/" + propertyName, new PdfString(propertyValue)));
}
document.Save(path);
document.Close();

Also the PDF file shouldn't be write protected. Otherwise you need to use a tool for unlocking the file before calling PdfSharp.