Greetings from Syncfusion support.
Query: “How can I send extra parameters on Post/Put/Delete?”
We have validated your query and currently we do not have support to send additional parameters to server using querystring during the CRUD operation. So we have considered your requirement as an improvement. At the planning stage for every release cycle, we review all open features and identify features for implementation based on specific parameters including product vision, technological feasibility, and customer interest. We have planned this feature for our Bi-Weekly Nuget release which is expected to be rolled out on or before 3rd December 2019. We will let you know once this improvement is implemented.
You can track the current status of this feature request and also communicate with us regarding the open features any time using our Feature Report page.
Till then we suggest you to achieve your requirement by sending the custom headers to WebAPI. Refer our UG document for your reference
If you are facing any issue while applying above workaround(custom headers), kindly get back to us with more details.