How do I make 2 (or more) calls with Adobe PDF Services and skip using the file system (in between?)

Question

It's fairly simple to make one call to Adobe PDF Services, get the result, and save it, for example:

// more stuff above
exportPdfOperation.execute(executionContext)
.then(result => result.saveAsFile(output))

But if I want to do two, or more, operations, do I need to keep saving the result to the file system and re-providing it (is that even a word ;) to the API?

Answer 1

So this tripped me up as well. In most demos, you'll see:

result => result.saveAsFile()

towards the end. However, the object passes to the completed promise, result, is a FileRef object that can then be used as the input to another call.

Here's a sample that takes an input Word doc and calls the API method to create a PDF. It then takes that and runs OCR on it. Both methods that wrap the API calls return FileRefs, so at the end I saveAsFile on it. (Note, this demo is using v1 of the SDK, it would work the same w/ v2.)

const PDFToolsSdk = require('@adobe/documentservices-pdftools-node-sdk');
const fs = require('fs');

//clean up previous
(async ()=> {

    // hamlet.docx was too big for conversion
    const input = './hamlet2.docx';
    const output = './multi.pdf';
    const creds = './pdftools-api-credentials.json';

    if(fs.existsSync(output)) fs.unlinkSync(output);

    let result = await createPDF(input, creds);
    console.log('got a result');
    result = await ocrPDF(result, creds);
    console.log('got second result');

    await result.saveAsFile(output);

})();

async function createPDF(source, creds) {

    return new Promise((resolve, reject) => {

        const credentials =  PDFToolsSdk.Credentials
        .serviceAccountCredentialsBuilder()
        .fromFile(creds)
        .build();

        const executionContext = PDFToolsSdk.ExecutionContext.create(credentials),
                createPdfOperation = PDFToolsSdk.CreatePDF.Operation.createNew();

        // Set operation input from a source file
        const input = PDFToolsSdk.FileRef.createFromLocalFile(source);
        createPdfOperation.setInput(input);

        let stream = new Stream.Writable();
        stream.write = function() {

        }
        
        stream.end = function() {
            console.log('end called');
            resolve(stream);
        }

        // Execute the operation and Save the result to the specified location.
        createPdfOperation.execute(executionContext)
        .then(result => resolve(result))
        .catch(err => {
            if(err instanceof PDFToolsSdk.Error.ServiceApiError
            || err instanceof PDFToolsSdk.Error.ServiceUsageError) {
                reject(err);
            } else {
                reject(err);
            }
        });

    });
}

async function ocrPDF(source, creds) {

    return new Promise((resolve, reject) => {

        const credentials =  PDFToolsSdk.Credentials
        .serviceAccountCredentialsBuilder()
        .fromFile(creds)
        .build();

        const executionContext = PDFToolsSdk.ExecutionContext.create(credentials),
            ocrOperation = PDFToolsSdk.OCR.Operation.createNew();

        // Set operation input from a source file.
        //const input = PDFToolsSdk.FileRef.createFromStream(source);
        ocrOperation.setInput(source);

        let stream = new Stream.Writable();
        stream.end = function() {
            console.log('end called');
            resolve(stream);
        }

        // Execute the operation and Save the result to the specified location.
        ocrOperation.execute(executionContext)
       .then(result => resolve(result))
       .catch(err => reject(err));

    });
}