How to use ConnectApi in a VF page having readOnly=“true” attribute?

Question

I've a VF page which have readOnly='true' attribute and I am trying to implement a button that when clicked will make a chatter post with some Blob content as element attachment using ConnectApi namespace classes in Apex.

I'm receiving this error:

Too many DML statements: 1 

My code looks something like this:

<apex:page readOnly="true" controller="MyTestPageController">
This is a test page.<br />
Post Content of some Visualforce Page as content into a Chatter Feed.<br />
<br />
<apex:commandButton value=" Post Content to Chatter " action="{!postToChatter}" />
</apex:>

The Code Apex class looks like this:

public with sharing class MyTestPageController {
    public MyTestPageController() { }

    public void postToChatter() {
        PageReference p                                         = Page.MyTestVFPage;

        ConnectApi.FeedItemInput feedItemInput                  = new ConnectApi.FeedItemInput();
        feedItemInput.subjectId                                 = 'me';

        ConnectApi.ContentCapabilityInput contentInput          = new ConnectApi.ContentCapabilityInput();
        contentInput.title                                      = 'My File';

        ConnectApi.FeedElementCapabilitiesInput capabilities    = new ConnectApi.FeedElementCapabilitiesInput();
        capabilities.content                                    = contentInput;

        feedItemInput.capabilities                              = capabilities;

        Blob myBlob                                             = p.getContent();
        ConnectApi.BinaryInput binInput                         = new ConnectApi.BinaryInput(myBlob, 'application/x-excel', 'Data_File_'+Datetime.now().getTime());

        ConnectApi.ChatterFeeds.postFeedElement(null, feedItemInput, binInput);
    }
}

Can anyone suggest if I can make ConnectApi do chatter post without me having to remove readOnly="true" VF Page attribute?

Answer 1

When you set readOnly attribute of page to true then it doesnot allow any DML statements.