Read, create, and update by using API
To read data through the API, you need to send a GET request to the API URL. Because the API is a REST service that has OData support, you can use the same functions that are available for OData web services.
To request a specific record, provide the SystemId (which is a GUID value) in the URL, as shown:
/api/mycompany/sales/v1.0/mycustomers(<guidvalue>)
When you want to create or update records through the API, you need to build your request the same way as you do with regular OData web services. You can use a POST method to create new records by using the API and the PATCH method to update a specific record. With PATCH, you only supply the fields that you want to change; the fields that aren't included in the request body keep their previous values. To delete a record, use the DELETE method.
For a PATCH method, you need to provide an If-Match header in the request before you can update an entity. This If-Match header uses the etag value that you can find in the OData response. If the etag that you provide doesn't match the current etag of the record, the record isn't updated.