I have a Approve/Reject workflow attached to a library. Is there a way to get the Workflow Instance Id from the list item using REST API?
I know it is possible with 'SPListItem.Workflows' in server-side API but in my case I need a REST equivalent.
Idea is to query Workflow History list with "List" and "WorkflowInstance" columns.
Question 1: Workflow Instance Id from the list item
Make a GET request to the following URL, you will get two fields name WorkflowInstanceID and WorkflowVersion along with other columns.
/_api/web/lists/GetByTitle('Your Library Name')/Fields
So you can get Workflow Instance Ids for all items in your library by following URL
/_api/web/lists/GetByTitle('Your Library Name')/Items?$select=WorkflowInstanceID
For a particular Item, let say ID of the Item is 11
/_api/web/lists/GetByTitle('Your Library Name')/Items(11)?$select=WorkflowInstanceID
Question 2: Idea is to query Workflow History
Workflow History is just a list like any other list. So you can apply same idea over here also.
/_api/web/lists/GetByTitle('Workflow History')/Items
In a SharePoint list if you attach any workflow it will a column with your workflow name. It is a Hyperlink column which can be used to get that full url to query workflow history list.
See below screenshot how it returns results from REST call.
I have used below query to get that
<<site url>>/_api/web/Lists/getByTitle('<<list title>>')/Items(<<item id>>)
It returns all columns but from results you will get that workflow column
