How can I post a feed item to my community using the REST API?

Question

My overall goal is to post a simple feed item to a community using the REST API. I am having some trouble with either the process or the configuration of my community, or both. Any pointers would be appreciated!

Here's what I am trying now:

1. I created a developer edition account and a community owned by me.
2. I first authenticate via the https://login.salesforce.com/services/oauth2/token endpoint. I think this step is fine, since I get back a json object with an access_token and instance_url.

3. I try to get a list of my communities from https://mycustomurl-developer-edition.na35.force.com/community/services/data/v38.0/connect/communities/. I get back json like below.

   { "communities": [ { "allowChatterAccessWithoutLogin": false, "allowMembersToFlag": false, "description": null, "id": "0DB410000008PYdGAN", "invitationsEnabled": false, "knowledgeableEnabled": false, "loginUrl": "https://mycustomurl-developer-edition.na35.force.com/community/s/login", "name": "Chris F. Test Community", "nicknameDisplayEnabled": false, "privateMessagesEnabled": false, "reputationEnabled": false, "sendWelcomeEmail": true, "siteUrl": "https://mycustomurl-developer-edition.na35.force.com/community", "status": "Live", "url": "/services/data/v38.0/connect/communities/0DB410000008PYdGAN", "urlPathPrefix": "community" } ], "total": 1 }

   I think I should use this id property as the subjectId to represent the community in the actual attempt to post my item.

4. I then tried to post a feed item to this community using the "Post a Feed Item" docs. I make an http post to https://mycustomurl-developer-edition.na35.force.com/community/services/data/v38.0/chatter/feed-elements?feedElementType=FeedItem&subjectId=0DB410000008PYdGAN&text=Post+from+rest. I set the authorization header, and I include the following as the body of the request:

   { "body" : { "messageSegments" : [ { "type" : "Text", "text" : "This is the content of my post." } ] }, "feedElementType" : "FeedItem", "subjectId" : "0DB410000008PYdGAN" }

I get back an error message that looks like this:

[
  {
    "errorCode": "INVALID_ID_FIELD",
    "message": "The object at parameter 'subjectId' value '0DB410000008PYdGAN' does not support Chatter."
  }
]

I am assuming that this subjectId is the correct one to use, based on the docs for the Feed Item. It's the id that is associated with my community, at least. If my community doesn't currently support Chatter, how can I enable that in my community? Is there anything else I'm doing that is obviously wrong?

Answer 1

The subjectId refers to the Id of the object you are posting to. Look at subjectId parameter here.

This is for making a feed post to an account's feed or a user's feed for example. Changing the subjectId to just me should post to your feed in that community since you are already using that community's REST endpoint.