create_message()

Create Message is one of the core functions in the system. Most other functions that create messages are a wrapper around create_message(). This functionality is allowed by the flexibility of the JSON input. The JSON keys assign the specific functionality.
Title and Message are required keys and they represent the title of the post and the body of the post respectively
CourseID assigns the message to a specific course. Most messages are assigned to a course, however it is also possible to assign a message to a group outside of a course.
>ParentMessageID is used to mark this message as a reply to another message.
PollType and PollItems must be included together. PollItems is the list of items to be voted on in the poll. PollType is an integer that provides the following 4 possibilities: 1 single vote,2 multi vote, 3 single vote with vote results summed together on each item.(not implemented), 4 multi vote with vote results summed together on each item.(not implemented)
PollItems is just an array of strings ["Item1","item2",....]
UsergroupID key allows a message to be assigned to an existing usergroup.
GroupMembers key requires a list of members and their type as [{"UserID":1,"UserType":1}...
It is an error to include both UsergroupID and GroupMembers keys because a message can only be part of one usergroup. GroupMembers creates its own usergroup. UsergroupID requires another one to already exist.

1 - The CourseID is not valid.
2 - Invalid Session.
3 - This user is not a member of selected course.
4 - Parent Message does not exist.
6 - Each groupmember must have a UserID.
7 - The UserID does not exist.
8 - Each groupmember must have a UserType.
9 - Invalid UserType.
10 - PollType must be a number between 1 and 4.
11 - PollItems must exist if PollType does.
12 - You cannot use an existing UserGroupID when creating a new group message.
13 - The CourseID, UserGroupID, and GroupMembers cannot all be Empty. A group of some type is required.
14 - Either this group does not exist or this user is not a member.
15 - This user does not have write permission into this group.
16 - Title field cannot be empty.
17 - Message field cannot be empty.
18 - A message cannot be a member of two UserGroups. The NextUserGroupID and GroupMembers keys cannot be used simultaneously.