Kendo spreadsheet: Creating a custom handler for the excelExport event and then exporting a spreadsheet with images via saveAsExcel result in an error

[Mario]

My goal is to handle the exportExcel event,  invoke the export saveAsExcel function, then pass the excel data to the server as a base64 string.
However if the spreadsheet contains images, and unhandled error occurs in the kendo script, which I have managed to track down via the unminified kendo.all.js and it seems to occur at this place:

'images is not defined' is the error message.

I've created Dojos which illustrate and reproduce the problem.
Clicking on the "Export" button will trigger the excel export:
 - Non-working Dojo with an image: https://dojo.telerik.com/AdIWETEY/15
 - Working Dojo (without images): https://dojo.telerik.com/iRebuTuV

[Neli]

Hi Mario,

I have debugged the provided samples and noticed that the images data is not presented in the e.workbook in the excelExport event handler (marked in yellow below):

excelExport: e => {
                e.preventDefault();              
                const dataURL = new kendo.ooxml.Workbook(e.workbook).toDataURL();
        	const base64 = dataURL.split(';base64,')[1];
                exportedWorkbooks.push(base64);
},

The issue is related to a bug that you will find linked below:

- https://github.com/telerik/kendo-ui-core/issues/6411

In the GitHub issue, you will find also a suggestion for retrieving the images data. 

Based on your report I have increased the priority of the issue. Thus, it could take precedence over other items in our priority queue.

I hope you will find the provided information helpful.

Regards,
Neli
Progress Telerik

[Mario]

Hi Neli,
Thank you for the swift response. We will implement the workaround if it's viable for our case. If not, we will wait for an update.

[Neli]

Hello Mario,

Please note that, as it is described in the Spreadsheet API, when external URLs are used for the images, they should reside on the same domain, or the server must be configured with the proper CORS headers, for the Spreadsheet to be able to fetch binary image data using a XMLHttpRequest. If it cannot fetch the image, export to Excel or PDF might not work.

I hope this helps.

Regards,
Neli
Progress Telerik

[Mario]

Hello and thanks for the response.
The images are not external - In fact, they are imported via the import function and the issue still persists with the same error...