Function SaveTo to save file to writer

[Donaldas]

Hi,
it would be great to have possibility to pass unlocked file to io.Writer interface.

Use case:
Web service downloads excel files from cloud storage and processes it. In case excel file is password protected, service should unlock it with provided password and upload unlocked file back to cloud storage.

Description

Current implementation allows to save unlocked filed to the file on file system via:
func (f *File) SaveAs(name string, opt ...Options) error

New function SaveTo would allow to upload unlocked file without persisting it on file system.
func (f *File) SaveTo(w io.Writer, opt ...Options) (int64, error)

Other option would be to allow reset options in order to save unlocked file using:

func (f *File) Write(w io.Writer) error
func (f *File) WriteTo(w io.Writer) (int64, error)
func (f *File) WriteToBuffer() (*bytes.Buffer, error)

Thanks!

[ronna-s]

Any update on this from the contributors?

[xuri]

This library has added the WriteTo function since version 1.4.1, which can be used to save the file to the writer. I will add options support for it recently.

[ronna-s]

Thanks for the quick reply @xuri I see the functions but they don't seem to set the contentType using the file extension as SaveAs does and that functionality is not exported (setContentTypePartProjectExtensions). I have a case for a file upload that doesn't need local storage.

[xuri]

Okay, thanks for your feedback. I will add support for it at this week.

[ronna-s]

I can create a proposal PR. Against v2 or master?

[xuri]

I have fixed this issue. Now the Save, Write and WriteTo function accept saving options, and here is an example for handle a workbook without a touch file system. Please upgrade to the master branch code, and this patch will be released in the next version.

[itmecho]

Heads up for anyone who might've had the same issue as me related to this!

I've just upgraded to 2.7.0 and this change has broken my code as the *excelize.File type no longer implements the standard library io.WriterTo interface.

I've had to implement this wrapper type to get it to work again:

package server

import (
	"io"

	"github.com/xuri/excelize/v2"
)

type fileWriterTo struct {
	*excelize.File
}

// WriteTo implements io.WriterTo
func (f *fileWriterTo) WriteTo(w io.Writer) (n int64, err error) {
	return f.File.WriteTo(w)
}

func wrapFileWriteTo(f *excelize.File) io.WriterTo {
	return &fileWriterTo{f}
}