How to add text to existing paragraph without breaking the style in C#?

Question

I have been trying to solve one problem in C# regarding updating paragraph text with some additional new text info:

I am not a C# developer, forgive me if the question is silly or easy to solve.

I have several paragraphs like this:

Alice is going to do some shopping.

Bob is a good guy.

Let's say, these paragraphs are written in Arial font with 11 pts. So I want to add some text after each paragraph.

The end result would be:

Alice is going to do some shopping.SomeText0

Bob is a good guy.SomeText1

I have tried this:

using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(document, true))
{
     List<Paragraph> paragraphs = paragraphService.GetParagraphs(wordDoc);
     foreach (Paragraph par in paragraphs) 
     {
         string paragraphText = paragraphService.ParagraphToText(par);
         paragraphText = textService.DeleteDoubleSpace(paragraphText);
         if (paragraphText.Length != 0) 
         {
             if (paragraphText == targetParagraph) 
             {
                 //Here I know that the added text will be corresponding to the my target paragraph.
                 //This paragraph comes from a JSON file but for simplicity I did not add that part.
                 par.Append(new Run(new Text("SomeText0")));
                 par.ParagraphProperties.CloneNode(true);
             }
         }
     }
 }

Adding the text works, but the style is not the same and some random style that I don't want. I want the newly added text to have the same font and size as the paragraph.

I have also tried several options, to make it Paragraph, just text, etc. But I could not find a solution.

Any help would be appreciated.

Answer 1

The open xml format stores paragraphs like the following

<w:p>
  <w:r>
    <w:t>String from WriteToWordDoc method.</w:t>
  </w:r>
</w:p>

Here,

1. p is the element represented by the Paragraph class,
2. r is the element represented by Run class, and,
3. t is the element represented by the Text class.

So you are appending a new <w:r> => Run element which has its own format settings, and since you don't specify any formatting, defaults are used.

EDIT 1: And as it seems, when there are parts in this paragraph that are formatted differently, there can be multiple Run elements under a paragraph.

So, instead you can find the last Run element containing a Text element and modify its text.

foreach (Paragraph par in paragraphs)
{
    Run[] runs = par.OfType<Run>().ToArray();
    if (runs.Length == 0) continue;
    Run[] runsWithText = runs.Where(x => x.OfType<Text>().ToArray().Length > 0).ToArray();
    if (runsWithText.Length == 0) continue;
    Text lastText = runsWithText.Last().OfType<Text>().Last();
    lastText.Text += " Some Text 0";
}

Hope this helps.