Can't update OData__ModerationStatus using HTTPSEND - rest

Question

I have tried to update the value of the OData__ModerationStatus column AKA "Approval Status" 3 different ways but only one works. Using VS 2013 the WorkFlow update Item activity from the toolbox and you can see that it's missing X-RequestDigest in the header and does not allow an update to the approval status and results in a security validation error. I believe the error is related to the missing header. Here is the code from the UpdateListItem.
RequestHeaders = (InArgument<DynamicValue>) ((Activity<DynamicValue>) new SetDynamicValueProperties()
{
Properties = {
{
"If-Match",
(InArgument) new InArgument<string>("*")
},
{
"X-HTTP-Method",
(InArgument) new InArgument<string>("MERGE")
},
{
"Accept",
(InArgument) new InArgument<string>("application/json;odata=verbose")
},
{
"Content-Type",
(InArgument) new InArgument<string>("application/json;odata=verbose")
}
}
}),
RequestContent = (InArgument) listItemProperties,
So I used 2 SendHttp activities, one to get the X-RequestDigest using a POST with the url siteurl/_api/contextinfo the second POST using the following headers & Body.
HEADER:
X-RequestDigest:[FormDigestValue from the previous POST]
Accept: application/json; odata=verbose
Content-Type: application/json; odata=verbose
IF-MATCH: *
X-HTTP-Method: MERGE
BODY: [I have tried the following 3]
String.Format("{ '__metadata': { 'type': '" + type + "' },'OData__ModerationStatus':'0' }")
{ '__metadata': { 'type': 'SP.Data.Shared_x0020_DocumentsItem' },
'OData__ModerationStatus':'0' }
Used a BuildDynamicValue activity to set the RequestContent.
All three come error with Microsoft.SharePoint.SPException: Invalid text value. A text field contains invalid data. If I use any other field it works, If i use Fiddler or Advanced Rest Client it updates the value.
Can someone help me understand or explain why it works via REST calls but I can't use VS and the UpdateItem/HTTPSend to set the value.
I have included a image with a successful workflow that updates the Title

Answer 1

We were able to get the scenario working.
After further investigations we could see that the workflow does not have Approve permissions.
We could see this by capturing the REST calls in fiddler for the workflow
{"error":{"code":"-2147024891, System.UnauthorizedAccessException","message":{"lang":"en-US","value":"Access denied. You do not have permission to perform this action or access this resource."},"innererror":{"message":"0x80070005owssvr.dll: (unresolved symbol, module offset=0000000000015BC3) at 0x000007F988885BC3\nMicrosoft.SharePoint.Library.ni.dll
The VS 2013 SP 2013 workflows are really like provider hosted apps and have a default permission which does not include approve items.
Perform the below steps to fix this
• Go to Site Settings  Site App Permissions
Find the App Workflow as copy the first guid as shown below
• Go to http:///_layouts/15/appInv.aspx.
Enter the Guid copied in previous step in the App ID and click on Lookup.
This will populate the Title, App Domain and Redirect URL columns.
Copy the below in Permission Request XML (do NOT change the scope)
<AppPermissionRequests>
<AppPermissionRequest Scope="http://sharepoint/content/sitecollection/web" Right="FullControl" /></AppPermissionRequests>
• Tested the workflow again and it started working.