Office.js For Excel Addin

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Introduction

Office.js is a powerful framework for building custom add-ins for Microsoft Office applications, including Excel. However, when working with Office.js, developers may encounter issues that can be frustrating to resolve. In this article, we will focus on troubleshooting issues related to the getFileAsync method in Excel, specifically when trying to retrieve a PDF file.

Understanding the Issue

When using the getFileAsync method in Excel, we are trying to retrieve a PDF file using the Office.FileType.Pdf enum value. However, despite the method returning a "succeeded" status, the file size is reported as 0, and the slice count is also 0. This issue is not present in Word, where the same code works as expected.

Code Snippet

The code snippet below demonstrates the loadFileBlob method, which is used to retrieve a PDF file using the getFileAsync method:

async loadFileBlob(officeDoc: OfficeDoc): Promise<OfficeDoc> {
    const Office = (window as any).Office;

    return new Promise((resolve, reject) => {
        Office.context.document.getFileAsync(
            Office.FileType.Pdf,
            { sliceSize: 65536 },
            async (asyncResult: any) => {
                if (asyncResult.status === Office.AsyncResultStatus.Failed) {
                    reject(asyncResult);
                    return;
                }
                console.log(asyncResult)
                const file = await asyncResult.value;

                if(file.size === 0) {
                    this.stateService.setErrorMessage($localize`We couldn't retrieve the file`)
                    return
                }

                // Prevent files larger than 10MB
                if (file.size > 10485760) {
                    file.closeAsync();
                    reject({ error: 'File too large', size: file.size });
                    return;
                } 
                try {
                    const docData = await this.getAllSlices(file);
                    const mergedData = this.mergeUint8Arrays(docData);

                    //Ensure the PDF blob is properly created
                    officeDoc.blob = new Blob([mergedData], { type: 'application/pdf' });

                    resolve(officeDoc);
                } catch (err) {
                    reject(err);
                } finally {
                    file.closeAsync();
                }
            }
        );
    });
}

Troubleshooting Steps

To troubleshoot this issue, we can follow these steps:

  1. Verify the file type: Ensure that the file type is set to Office.FileType.Pdf and not Office.FileType.Compressed, which is a different enum value.
  2. Check the slice size: Verify that the slice size is set to a reasonable value, such as 65536, which is the default value.
  3. Inspect the async result: Log the asyncResult object to inspect its properties, including the status and value properties.
  4. Verify the file size: Check the file size property of the file object to ensure it is not 0.
  5. Check for errors: Verify that there are no errors in the asyncResult object or in the file object.

Possible Causes

Based on the troubleshooting steps above, possible causes of this issue include:

  1. Incorrect file type: Using the wrong file type enum value, such as Office.FileType.Compressed instead of Office.FileType.Pdf.
  2. Incorrect slice size: Setting the slice size to an unreasonable value, such as 0 or a very large value.
  3. Async result issues: Issues with the asyncResult object, such as a failed status or an empty value property.
  4. File size issues: Issues with the file size property of the file object, such as a size of 0.

Conclusion

In conclusion, troubleshooting issues with the getFileAsync method in Excel can be challenging, but by following the steps outlined above, developers can identify and resolve common issues. By verifying the file type, slice size, async result, and file size, developers can ensure that their code is working correctly and that the file is being retrieved successfully.

Additional Tips

  • Verify the Office.js version: Ensure that the Office.js version is up-to-date and compatible with the Excel version being used.
  • Check the Excel version: Verify that the Excel version is compatible with the Office.js version being used.
  • Use the Office.js debugger: Use the Office.js debugger to inspect the async result and file object properties.
  • Consult the Office.js documentation: Consult the Office.js documentation for additional information on troubleshooting issues with the getFileAsync method.
    Office.js for Excel Add-in: Troubleshooting getFileAsync Issues - Q&A ===========================================================

Introduction

In our previous article, we discussed troubleshooting issues with the getFileAsync method in Excel using Office.js. In this article, we will provide a Q&A section to address common questions and concerns related to this topic.

Q: What are the possible causes of the getFileAsync method returning a file size of 0?

A: The possible causes of the getFileAsync method returning a file size of 0 include:

  • Incorrect file type: Using the wrong file type enum value, such as Office.FileType.Compressed instead of Office.FileType.Pdf.
  • Incorrect slice size: Setting the slice size to an unreasonable value, such as 0 or a very large value.
  • Async result issues: Issues with the asyncResult object, such as a failed status or an empty value property.
  • File size issues: Issues with the file size property of the file object, such as a size of 0.

Q: How can I verify the file type and slice size in my code?

A: To verify the file type and slice size in your code, you can use the following steps:

  • Verify the file type: Ensure that the file type is set to Office.FileType.Pdf and not Office.FileType.Compressed, which is a different enum value.
  • Check the slice size: Verify that the slice size is set to a reasonable value, such as 65536, which is the default value.

Q: What are some common issues with the asyncResult object?

A: Some common issues with the asyncResult object include:

  • Failed status: The asyncResult object may have a failed status, which indicates that the getFileAsync method failed to retrieve the file.
  • Empty value property: The asyncResult object may have an empty value property, which indicates that the getFileAsync method failed to retrieve the file.

Q: How can I troubleshoot issues with the file size property of the file object?

A: To troubleshoot issues with the file size property of the file object, you can use the following steps:

  • Verify the file size: Check the file size property of the file object to ensure it is not 0.
  • Check for errors: Verify that there are no errors in the asyncResult object or in the file object.

Q: What are some additional tips for troubleshooting issues with the getFileAsync method?

A: Some additional tips for troubleshooting issues with the getFileAsync method include:

  • Verify the Office.js version: Ensure that the Office.js version is up-to-date and compatible with the Excel version being used.
  • Check the Excel version: Verify that the Excel version is compatible with the Office.js version being used.
  • Use the Office.js debugger: Use the Office.js debugger to inspect the async result and file object properties.
  • Consult the Office.js documentation: Consult the Office.js documentation for additional information on troubleshooting issues with the getFileAsync method.

Conclusion

In conclusion, troubleshooting issues with the getFileAsync method in Excel using Office.js can be challenging, but by following the steps outlined in this article, developers can identify and resolve common issues. By verifying the file type, slice size, async result, and file size, developers can ensure that their code is working correctly and that the file is being retrieved successfully.