It was all looking good until we needed to update sharepoint – e.g. a list, a list item etc.
The MS Course notes say – “if you’re in SharePoint you can get the Form Digest from the main SharePoint Form….”
What about if you’re running outside of SharePoint (a Provider App – they now call it, or Cloud Hosted…depending on who wrote the help article)
The Answer – make a REST call to get the ‘Context Info’ first, then you’ll have the form digest and you’re done.
http://msdn.microsoft.com/en-us/library/fp142386(office.15).aspx#bk_synchronize (just at the top of this page)
Table 1. SPContextWebInformation structure initialization properties
Gets the server-relative URL of the nearest site.
Gets the server-relative URL of the root of the site collection that the site is contained within.
If the nearest web is the root of a site collection, then the value of the webFullUrl property is equal to the siteFullUrl property.
Gets the server's request form digest.
Gets the current version of the REST library.
Gets the versions of the schema of the REST/CSOM library that are supported.
To access this information, use the /contextinfo operator. For example:
To increase security against cross-site scripting attempts, the /contextinfo operator accepts only POST requests.