facebook.senders: Pull the list of senders from a set of inbox conversations
In facebook.S4: Access to Facebook API V2 via a Set of S4 Classes

Description Usage Arguments Details Value Author(s) See Also Examples

facebook.senders pulls information about the users who have sent a message in a set of inbox page conversations in a FacebookConversationsCollection-class and pushes into a FacebookMixedCollection-class instance.

1 2	facebook.senders(id, token = NULL, parameters = list(), n = getOption("facebook.maxitems"), .progress = create_progress_bar())

`id`	An existing `FacebookConversationsCollection`.
`token`	Either a temporary access token created at https://developers.facebook.com/tools/explorer or the OAuth token created with `fbOAuth`. If it's `NULL`, the token from `id` is used. Otherwise, no query is performed to the Facebook Graph API and an empty Collection is returned.
`parameters`	A list of parameters to be added to the Facebook Graph API query. For more information on the accepted parameters, see: https://developers.facebook.com/docs/graph-api/using-graph-api.
`n`	An integer value with the maximum number of senders to be pulled for each conversation in `id`. It can be set to `Inf` to pull out any sender of a given conversation and assumes the default value to `facebook.maxitems` global option if missing.
`.progress`	progress_bar object as defined in the plyr package. By default the `none` progress bar is used, which prints nothing to the console. See create_progress_bar for details.

This function requires the use of a OAuth page access token with read_pages_mailboxes permission granted.

Only the id and the type is returned in a mixed collection. Then, a proper collection for each type could be built accordingly.

Since this is a finder function, duplicated id won't be removed to the output collection unless they also have the same parent.

A collection of users in a FacebookMixedCollection-class object with the id and the type for each element included.

Gabriele Baldassarre https://gabrielebaldassarre.com

FacebookConversationsCollection, facebook.search, facebook.participants

Other FacebookFinders: facebook.participants

## Not run: 
## See examples for fbOAuth to know how token was created.
 load("fb_oauth")
 
## Returns the conversations of a given page
 conversations <- FacebookPagesCollection(id="9thcirclegames", fb_oauth) %>%
   FacebookConversationsCollection()
 
## Who sent a message to the page
 senders <- facebook.senders(conversations) %>% FacebookUsersCollection()

## End(Not run)