Getting started with iText - Part 18 (Concatenating PDF Forms)

In Part 18 we translate the ConcatenateForms.java example. It is an extremely simple example that concatenates multiple PDF forms. You can run this example with MX7 or CF8 and theoretically MX6 (if you have installed iText). Of course if you are running CF8 you should use the new cfpdf tag for merging PDF files and forms instead. A CF8 only example is included at the end for comparison purposes.

*Groan* Do I have to RTM?

Truth be told some of us have an unfortunate tendency to skim articles, and ignore the referenced links, so we can jump to the interesting part: the code. (Now when I say "us" .. I do not mean myself of course.. ;) This entry is a good example of how not reading the documentation can burn you.

Now the iText tutorial is a bit old, but it does mention two important things about the PdfCopyFields object used in this example. First it states the PdfCopyFields class keeps all documents in memory unlike PdfCopy. That is an important distinction. Second it notes that if you have fields with the same name they will be merged so, it's probably a good idea to rename them if that's the case.

As a test, I created two copies of the SimpleRegistrationForm.pdf file. Then used the sample code to concatenate the two files. Because fields with the same name are merged, typing a value into one of the fields, such as "name", effects all of the fields with that same name. Since the process takes the separate forms and merges them into one AcroForm, this behavior makes sense. But I think it is worth emphasizing so this behavior does not take you by surprise. Note, using CF8's cfpdf tag to merge forms produces the same results.

Now for the good part ..

What you will need for this example

Download the following (2) files from the iText site and place them in the same directory as your .cfm script

• SimpleRegistrationForm.pdf
  
• TextFields.pdf

Code

Documentation: Manipulating existing PDF documents
Source: ConcatenateForms.java

iText Example

<h1>Concatenate PDF Forms example</h1>
Concatenates 2 PDF files with forms. The resulting PDF has 1 merged AcroForm.<br>
<cfscript>
    savedErrorMessage = "";

    // cfSearching: All file paths are relative to the current directory
    fullPathToOutputFile = ExpandPath("./ConcatenatedForms.pdf");
    // cfSearching: Using an array of paths here instead of separate variables for each file
    arrayOfInputFiles = arrayNew(1);
    arrayAppend(arrayOfInputFiles, ExpandPath("./SimpleRegistrationForm.pdf"));
    arrayAppend(arrayOfInputFiles, ExpandPath("./TextFields.pdf"));
    
    try {

        outStream = createObject("java", "java.io.FileOutputStream").init( fullPathToOutputFile );
        copy = createObject("java", "com.lowagie.text.pdf.PdfCopyFields").init(outStream);
        PdfReader = createObject("java", "com.lowagie.text.pdf.PdfReader");
        
        for (fileIndex = 1; fileIndex LTE arrayLen(arrayOfInputFiles); fileIndex = fileIndex + 1) {
            reader = PdfReader.init( arrayOfInputFiles[fileIndex] );
            copy.addDocument(reader);
        }

        WriteOutput("Finished!");
    }
    catch (java.language.Exception de) {
        savedErrorMessage = de;
    }
    // cfSearching: close iText and output stream objects
    if (IsDefined("copy")) {
        copy.close();
    }
    if (IsDefined("outputStream")) {
        outputStream.close();
    }
</cfscript>


<!--- show any errors --->
<cfif len(savedErrorMessage) gt 0>
    Error. Unable to create file
    <cfdump var="#savedErrorMessage#">
</cfif>

ColdFusion 8 example

<h1>Concatenate PDF Forms example (ColdFusion 8)</h1>

<cfset listOfInputFiles = ExpandPath("./SimpleRegistrationForm.pdf")>
<cfset listOfInputFiles = listAppend(listOfInputFiles, ExpandPath("./TextFields.pdf"))>
<cfset fullPathToOutputFile = ExpandPath("./ConcatenatedForms.pdf")>

<cfpdf action="merge"
    source="#listOfInputFiles#"
    destination="#fullPathToOutputFile#"
    keepbookmark="true"
    overwrite="true">