Custom Coding in SharePoint 365 e3

Hi,

I have a Request Form based on InfoPath & SP 365 Site.

I need Approve Reject Functionality on Info Path Form. (Example if user click on Approve button Work Flow go to in another stage)

Now the problem is:

• SharePoint Online doesn’t support Farm solutions, Farm solutions are registered in the global assembly cache and run under full trust.
• The full-trust solutions are not available to SharePoint Online customers.
• SP SITE Constructor is Restricted in Sandbox
• SP Context is null InfoPath Custom Solution(due to Form is running in Sandbox solution)

• SP Online not support InfoPath Form with Full Trust

Than how should I Approve and Reject Request in Workflow Task List using Custom Solution.

Kindly Advice

Thanks,

Taha