Find and replace merge fields with other merge fields

[NigelGay]

The tags we use for repeating blocks in our Word templates and merge fields that look like rb:start:BlockOne and end with rb:end:BlockOne. If I try to do doc.getMailMerge().setRegionStartTag(“rb:start”), I get an exception “A mail merge region tag can not contain reserved separating characters”. We have 1000s of templates, updating them manually is not feasible.

So, I am trying to do some prep work on the document prior to the merge, to change all the rb:start: mail merge tags to TableStart: and all the rb:end: tags to TableEnd: similar to Preparing document to use Mail Merge except I don’t believe I can make a regex pattern that finds merge fields.

What would be ideal is being able to use setFieldMergingCallback, and in the fieldMerging method do like:
if (field.getFieldName().startsWith(“rb:start:”))
field.setFieldName(“TableStart:” + field.getFieldName().substring(9));

But you cannot do this, there is no “setFieldName” method. As per example I linked, you can create merge fields with DocumentBuilder, but how do I know where to insert them? FieldMergingArgs tells you nothing about where the merge field is located that would enable you to use DocumentBuilder to insert a new merge field where the old merge field was located.

Or maybe I just don’t have the right approach? Many thanks for any suggestions.

[alexey.noskov]

@NigelGay If you would like to rename merge fields in your templates, you can use code like the following:

Document doc = new Document("C:\\Temp\\in.docx");

for (Field f : doc.getRange().getFields())
{
    if (f.getType() == FieldType.FIELD_MERGE_FIELD)
    {
        FieldMergeField mf = (FieldMergeField)f;
        if (mf.getFieldName().startsWith("rb:start:"))
            mf.setFieldName("TableStart:" + mf.getFieldName().substring(9));
        if (mf.getFieldName().startsWith("rb:end:"))
            mf.setFieldName("TableEnd:" + mf.getFieldName().substring(7));
    }
}
doc.save("C:\\Temp\\out.docx");

@NigelGay

But you cannot do this, there is no “setFieldName” method. As per example I linked, you can create merge fields with DocumentBuilder, but how do I know where to insert them? FieldMergingArgs tells you nothing about where the merge field is located that would enable you to use DocumentBuilder to insert a new merge field where the old merge field was located.

In IFieldMergingCallback you can use DocumentBuilder.moveToField method to move the cursor to the location of the mergefield and then insert the required content.