I need a good example of how to MERGE data using REST in SharePoint 2013 Workflows. I can't seem to make it work from the examples I have seen.

http://blog.ctp.com/2014/03/12/updating-list-items-using-sharepoint-2013-workflow-engine/

I get a bad response when I attempt to change the tile of an item.

My goal is to create an approval workflow with REST calls.  I want to create a reusable workflow and not directly make workflows on each list.

Anyone? 

I can't seem to figure out what I'm doing wrong.  Anyone?

I keep reading about Approvals not being possible with REST.  Seriously?

I keep getting blocked.  I don't want to create an approval process for every flipping library.  I should be able to make a reusable workflow do approvals!@@@

I finally have a working example but I'm confused as to why what I want is failing.

If I try to create an item in a list it works.

URL:
http://sharepointtest/_api/web/lists/getbytitle('Locations')/items

Header:
Accept: application/json;odata=verbose
Content-Type:  application/json;odata=verbose

Metadata:
type: SP.Data.LocationsListItem

Parameters:
__metadata:  Metadata
Title: New Item name

What I want to do is update a specific item in a document library. 

Can anyone help fill in the blanks?

I tried this but I get "InternalServerError".

URL:
http://sharepointtest/_api/web/lists/getbytitle('Information%20Systems')/items

Header:
Accept: application/json;odata=verbose
Content-Type:  application/json;odata=verbose

Metadata:
type: SP.Data.Information_x0020_SystemsItem

Parameters:
__metadata:  Metadata
Title: New Item name

I was hoping above would create an item.

Trying to update an item has the same effect.  I tried this:

URL:
http://sharepointtest/_api/web/lists/getbytitle('Information%20Systems')/items('90')

Header:
Accept: application/json;odata=verbose
Content-Type:  application/json;odata=verbose
X-HTTP-Method: MERGE
IF-MATCH: *

Metadata:
type: SP.Data.Information_x0020_SystemsItem

Parameters:
__metadata:  Metadata
Title: New Item name

This looks promising.

https://msdn.microsoft.com/EN-US/library/office/dn450841.aspx#bk_FileApprove

It looks like I need to get to the file through a different REST query to approve it.

Tried this and got UnAuthorized.

URL:
http://sharepointtest/_api/web/getfilebyserverrelativeurl('/Information%20Systems/Certificate%20Authority%20Setup.docx')/approve(comment='Check-in%20comment%20for%20the%20approval.')

Header:
Accept: application/json;odata=verbose
Content-Type:  application/json;odata=verbose
X-HTTP-Method: MERGE
IF-MATCH: *

Metadata:
type: SP.Data.Information_x0020_SystemsItem

Parameters:
__metadata:  Metadata

Finally I got it.

To approve a doc you have to use the Approve function like above.

I was getting access denied because I hadn't authorized the application permissions.

example from site:  http://sharepointryan.com/2013/09/10/create-a-sharepoint-site-spweb-using-rest-in-spd-2013-workflow/

Hi David,

Glad that you solved the issue, and thanks for sharing, this will benifit others who have similar issue in the future.

Thanks

Daniel Yang