Copy attachments as temporary files before sending

[adamski]

This was necessary in my case as the files were local to the app. May not be necessary in other cases, in which case a boolean switch should be added.

[adamski]

@timscott your input on this PR would be useful.

[adamski]

Should probably fail here as temporaryFile will be null

[timscott]

I guess you are solving the problem that the mail program will not have permission to the original file if it's an app asset?

I have solved that in my use case, by using react-native-fs to copy asset files once to RNFS.ExternalDirectoryPath. I would rather not copy several files each time the user attaches.

However, I agree that it would be good to handle this case in a built-in way, and copying to a temp file seems fine. Some questions:

1. What if the file is already in a location that is accessible to the mail program? It would be better not to copy it. You mentioned a switch, but can't the code detect if it's in an accessible location?
2. I didn't see where the temp file is cleaned up. Maybe that's not possible since you don't know when the mail app is done with it.
3. When you create the temp file, does that overwrite any existing file with the same path? Bad if not, I guess.

[adamski]

Thanks for those points. I had a look and found some documentation which looks like this issue could be avoided by using the FileProvider: https://developer.android.com/training/secure-file-sharing/share-file

[timscott]

Cool, it would be great if you could get that working. It would allow me to delete some code from my app. My favorite coding is deleting code!