How to identify the GUID of field 'Timesheet Manager', which is present in OData by name 'ResourceTimesheetManageId'? I don't want to know GUID of resource who is Timesheet Manager, I want to know GUID of this field 'Timesheet Manager'.
Get yourself Sharepoint Manager (or other free SharePoint browsing tool) it will allow you to browse through the properties of the site collection to the level of item/field and find the GUID.
I don't know of a way to get the id, or if a uid exists for that field. Traditionally, the databases for project server have not been documented, as we're supposed to use the API and not the connect directly to the draft or published database (which exist in on-prem installs). In both the reporting database (on-prem) and the rest api, UIDs are available for all custom fields, but not OOB fields.
After having discussion with both the above users and I have tried both the solutions also, I have reached to conclusion that there is no GUID for this field 'Timesheet Manager' or it is not possible to identified, though almmost all the data is fetched using both the above tools. Anybody has some other knowledge on this, please let me know.
Connect-PnPOnline https://my.sharepoint.com/sites/someSite $l = Get-PnPList ListName Get-PnPField -List $l FieldName | Select Id