SharePoint 2013 REST API Request Token: The given key was not present in the dictionary

Question

I am trying to post data to a SharePoint 2013 REST API using Python. I am able to successfully acquire the required X-RequestDigest using the method from this post.

I have already tried solutions from here and here.

I can extract the required token every time, but I get this response from the server when I try to use it:

<?xml version="1.0" encoding="utf-8"?><m:error xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
<m:code>-1, System.Collections.Generic.KeyNotFoundException</m:code>
<m:message xml:lang="en-US">The given key was not present in the dictionary.</m:message>
<m:innererror><m:message>The given key was not present in the dictionary.</m:message>
<m:type>System.Collections.Generic.KeyNotFoundException</m:type>
<m:stacktrace>   
at System.Collections.Generic.Dictionary`2.get_Item(TKey key)&#xD;
   at Microsoft.SharePoint.Client.Rest.RestRequestProcessor.ReadRequestODataObject(ServerStub serverStub, Object entity)&#xD;
   at Microsoft.SharePoint.Client.Rest.RestRequestProcessor.InvokeMethodWithRequestODataEntry(Object target, ServerStub serverStub, String methodName)&#xD;
   at Microsoft.SharePoint.Client.Rest.RestRequestProcessor.TryAddEntity(Object entity, ServerStub serverStub, Object&amp; newEntity)&#xD;
   at Microsoft.SharePoint.Client.Rest.RestRequestProcessor.Process()&#xD;
   at Microsoft.SharePoint.Client.Rest.RestRequestProcessor.ProcessRequest()&#xD;
   at Microsoft.SharePoint.Client.Rest.RestService.ProcessQuery(Stream inputStream, IList`1 pendingDisposableContainer)</m:stacktrace></m:innererror></m:error>

I use the following code:

# First, get security token
token_url = "https://example.com/_api/contextinfo"
tr = requests.post(token_url, auth=HttpNtlmAuth(creds[0], creds[1]),verify=False)
tokenRoot = ElementTree.fromstring(tr.content)

# Since the namespace will not be parsed, it is hardcoded into the string
token = tokenRoot.find("{http://schemas.microsoft.com/ado/2007/08/dataservices}FormDigestValue").text
print(token)

headers = {'X-RequestDigest': token}
post_url = "https://example.com/_api/web/lists/getbyTitle('listname')/items"

payload = {'__metadata': {'type': 'SP.Data.ListName'},'Title': 'test', 'date_observation': '2015-08-10T22:00:00Z'}

r = requests.post(post_url, data=json.dumps(payload), auth=HttpNtlmAuth(creds[0], creds[1]), headers = headers, verify=False)
print(r.status_code)

Any ideas whatsoever?

Answer 1

I came across this error when there was a malformed field in a list. I found it by using the Developer Dashboard and just making the api call from there.

It showed me that there was a lookup list that it could not open, and the lookup field had a render error.

Maybe you are in a similar situation?

Answer 2

Question resolved. The error message is completely misleading. It has nothing to do with the token - the problem lies within the strict POST message format SharePoint is requiring. If you use the following headers for your POST request, everything works fine.

headers = {'X-RequestDigest': token,
           'Accept': 'application/json; odata=verbose',
           'Content-Type': 'application/json; odata=verbose',
           'Content-Length': len(json.dumps(payload))}