Summer16EmailAction.java

global class Summer16EmailAction {
  @invocableMethod
  global static void renderEmailToChatter(List<EmailRequest> emails) {
    List<ConnectApi.BatchInput> batchInputs = new List<ConnectApi.BatchInput>();
    for(EmailRequest email : emails) {
      ConnectApi.FeedItemInput input = new ConnectApi.FeedItemInput();
      input.subjectId = email.getFeedId();
      ConnectApi.MessageBodyInput body = new ConnectApi.MessageBodyInput(); 
      body.messageSegments = new List<ConnectApi.MessageSegmentInput>();
      ConnectApi.TextSegmentInput textSegment = new ConnectApi.TextSegmentInput();
      textSegment.text =  email.getPlainTextBody();
      body.messageSegments.add(textSegment); 
      input.body = body;
      ConnectApi.BatchInput batchInput = new ConnectApi.BatchInput(input);
      batchInputs.add(batchInput); 
    }
    ConnectApi.ChatterFeeds.postFeedElementBatch(Network.getNetworkId(), batchInputs);
  }
  
  global class EmailRequest {
    @invocableVariable(required=true) global Id whoId;
    @invocableVariable(required=true) global Id whatId;
    @invocableVariable(required=true) global Id templateId;
    @invocableVariable(required=true) global Id feedId;
    private Messaging.SingleEmailMessage msg;
    
    global Id getFeedId() {return this.feedId;}
    global String getPlainTextBody() { return this.render().getPlainTextBody();}
    private Messaging.SingleEmailMessage render() { return this.msg = Messaging.renderStoredEmailTemplate(templateId, whoId, whatId);}        
  }
}

Usage.md

OK, I put some debug statements in there, and this is all it's showing

[26]|DEBUG|ConnectApi.MessageBodyInput[messageSegments=(ConnectApi.TextSegmentInput[text=])]

I added a debug of

System.debug(email.getPlainTextBody());

and it just returned nothing.

The email is actually sending, and the rest of the process is working.

So I'm not sure where to turn next with it. I may have to just give up on this idea for now. So close, yet so far, because it works perfectly well for HTML emails.

@jodim -

Id contactId = '0033600000J3DZ7';
Id accountId = '0013600000QG6qS';
Id templateId = '00X36000001996H'
Messaging.SingleEmailMessage msg = Messaging.renderStoredEmailTemplate(templateId, contactId, accountId);
system.debug(msg.getPlainTextBody());