Mail Merge Word Document and Convert output to PDF in Node

Aspose.Words Cloud Product Family
1

I am trying to do a mail merge, but I need the resulting output to be a PDF. So I am trying to take the result of the merge, and pass it to the convert function, but I am running into the following error:

body: WordsApiErrorResponse {
    error: ApiError {
      message: 'Unexpected end of Stream, the content may have already been read by another component. '
    }
}

Here is the code:

const wordsApi = new WordsApi(clientId, secret);

let requestTemplate = fs.createReadStream("TestExecuteTemplate.docx");
let requestData = fs.createReadStream("TestExecuteTemplateData.json");

const mailMergeRequest = new ExecuteMailMergeOnlineRequest({
    template: requestTemplate,
    data: requestData,
    withRegions: true
});

wordsApi.executeMailMergeOnline(mailMergeRequest)
.then((mailMergeRequestResult) => {
    console.log("merge complete");
    const convertRequest = new ConvertDocumentRequest({
        document: Readable.from(mailMergeRequestResult.body),
        format: "pdf"
    });
    wordsApi.convertDocument(convertRequest)
    .then((convertRequestResult) => {
        console.log("convert complete");
        fs.writeFile('output.pdf', convertRequestResult.body, function (err) {
            if (err) return console.log(err);
            console.log('file saved');
        });
    })
    .catch((err) => {
        console.log(err);
    });

})
.catch((err) => {
    console.log(err);
});

What should I be doing differently?

2

@danobri

Please amend the convertRequest code as following, it will fix the issue.

 const convertRequest = new ConvertDocumentRequest({
        //document: Readable.from(mailMergeRequestResult.body),
	document: mailMergeRequestResult.body,
	format: "pdf"
    });
3

That doesn’t work, as it’s a type mismatch - body is a Buffer, and document is a Readable.

image.png (67.7 KB)

4

The file conversion does complete successfully without Readable.from(), but it causes the type mismatch shown in the screenshot. So maybe there is something not quite right about the typings file?

5

@danobri

Thanks for your feedback. We have logged an internal ticket WORDSCLOUD-1747 for more investigation. We will share the results with you asap.

6

The issues you have found earlier (filed as WORDSCLOUD-1747) have been fixed in this update. This message was posted using Bugs notification tool by Ivanov_John

7

@danobri

About the above issue, it is the expected behavior of Node SDK. The return type of executeMailMergeOnline method is Promise< model.WordsIncomingMessage< Buffer > >. And the parameter type for ConvertDocumentRequest.document is Readable. So Node.js can’t convert Buffer to Readable and displays the error.

Recently we have added a new feature, a batch of requests, and changed the result type for most of the methods. You can use this feature for the scenario.

The best idea is to use a batch request for two requests: ExecuteMailMergeOnlineRequest and ConvertDocumentRequest. Use request1.useAsSource() to redirect the result of the first request to the second request. Both requests are executed on the API side. It is a simple, fast, and convenient way to do it. Look at batch tests for examples.

If you would like to follow an old-fashioned way with consecutive requests, you need to convert Buffer to stream type. There are many ways. For instance, buffer-to-stream package ( buffer-to-stream - npm )

8

You don’t need an external package to convert a Buffer to a Readable stream. The native Readable.from method works fine for this purpose. I have confirmed this is working in the latest version.

That said - using the batch function does seem like a better way to handle multiple requests. Thanks for providing the additional information.

9

@danobri

Thanks for your feedback. It is good to know that your requirement is fulfilled.

10

One follow up question - is a batch request treated as one API request from a pricing standpoint, or is each step of the batch treated as API request from a billing standpoint?

11

@danobri

Please note, in the batch request each API call is charged as a separate credit not all APIs as a whole.