how can I put a content in a mergefield in docx

Question

I\'m developing a web application with asp.net and I have a file called Template.docx that works like a template to generate other reports. Inside this Template.docx I have

Answer 1

Frank Fajardo's answer was 99% of the way there for me, but it is important to note that MERGEFIELDS can be SimpleFields or FieldCodes.

In the case of SimpleFields, the text runs displayed to the user in the document are children of the SimpleField.

In the case of FieldCodes, the text runs shown to the user are between the runs containing FieldChars with the Separate and the End FieldCharValues. Occasionally, several text containing runs exist between the Separate and End Elements.

The code below deals with these problems. Further details of how to get all the MERGEFIELDS from the document, including the header and footer is available in a GitHub repository at https://github.com/mcshaz/SimPlanner/blob/master/SP.DTOs/Utilities/OpenXmlExtensions.cs

private static Run CreateSimpleTextRun(string text)
{
    Run returnVar = new Run();
    RunProperties runProp = new RunProperties();
    runProp.Append(new NoProof());
    returnVar.Append(runProp);
    returnVar.Append(new Text() { Text = text });
    return returnVar;
}

private static void InsertMergeFieldText(OpenXmlElement field, string replacementText)
{
    var sf = field as SimpleField;
    if (sf != null)
    {
        var textChildren = sf.Descendants();
        textChildren.First().Text = replacementText;
        foreach (var others in textChildren.Skip(1))
        {
            others.Remove();
        }
    }
    else
    {
        var runs = GetAssociatedRuns((FieldCode)field);
        var rEnd = runs[runs.Count - 1];
        foreach (var r in runs
            .SkipWhile(r => !r.ContainsCharType(FieldCharValues.Separate))
            .Skip(1)
            .TakeWhile(r=>r!= rEnd))
        {
            r.Remove();
        }
        rEnd.InsertBeforeSelf(CreateSimpleTextRun(replacementText));
    }
}

private static IList GetAssociatedRuns(FieldCode fieldCode)
{
    Run rFieldCode = (Run)fieldCode.Parent;
    Run rBegin = rFieldCode.PreviousSibling();
    Run rCurrent = rFieldCode.NextSibling();

    var runs = new List(new[] { rBegin, rCurrent });

    while (!rCurrent.ContainsCharType(FieldCharValues.End))
    {
        rCurrent = rCurrent.NextSibling();
        runs.Add(rCurrent);
    };

    return runs;
}

private static bool ContainsCharType(this Run run, FieldCharValues fieldCharType)
{
    var fc = run.GetFirstChild();
    return fc == null
        ? false
        : fc.FieldCharType.Value == fieldCharType;
}