I am looking for an option where a custom meta value will be saved when user uploads an attachment.
Lets say I need a meta key _example_meta_key and want to save meta value of this as ex087659bh (It will be a randomly generated number, I can take care of this.)
However, The problem is, I can't seem to find any filters to add custom meta value on upload. There are some tutorials which shows the way to add fields in media edit form but I need this to be executed at the time of file upload.
Any help would be much appreciated.