With current 1705 release now cloud application studio user can extends PSM released OData services with extension fields.
Use case : As a business requirement you have extended standard BO with fields, and now other party/system who is consuming OData service of that standard BO wants extended fields in OData Service.
Below is the step by step guide to extend Odata service in cloud studio.
Extend standard BO, for example I have extended SericeRequest BO with fields shown in image
2. New content OData Extension can be created from ‘Add New Item’, click on Add New Item -> a new icon with name “OData Extension” will be available under SAP.
give a name to Odata extension and click on ‘OK’
3. A new dialog will appear to select available Odata service, Only PSM enable Odata services will be shown in drop-down, select relevant service which is based on enhanced standard BO and click on ‘OK’
4. It will navigate you to the browser and opening “Odata Editor” key user tool. If you are not already logged on to the SAP cloud solution, you will be prompted to log on (Use your SDK user for log-in)
5.OData Editor has two part, on the right side it has OData Service here all the nodes are listed of that services, Whatever node you have extended in BO, select it here (it should show mark as selected), on Left side it shows all element of that node.
6. From the right side under the Business Object, you can see PDI extension field as editable field, you can select and deselect it.
After selecting this field click on button Save and then Activate.
7. After successful activation status get changed to Active and Service URL will be generated.
8. Come back to PDI and On Refresh of solution, you will see a new content with. xodata extension in solution explorer
Other Way for Activation is from PDI, if you left inactivate from the browser then it will appear in SDK with inactivate flag, Right click on .xodata content and Activate
9. To verify that extended field in BO is added or not you can check service metadata, Open Service URL in a browser and search the field recently added ( you can find metadata link in Odata editor)
Now Odata service is ready to use with extension fields.
Note: It does not support custom node extension and its fields to extends OData services.
For further usage how to consume C4C Odata you can follow this blog