Am creating a vanilla Napa app and am seeking to reference the host URL as follows:
var ctx = new SP.ClientContext(_spPageContextInfo.webServerRelativeUrl);
Yet _spPageContextInfo is being flagged as undefined. From what I have read this should be baked into SharePoint, so I cannot understand why it is not defined.
I'm sure the solution is simple, but can someone please advise?
you need to add the "SharePoint:SharePointForm" control to your page body.
Look at this extremely similar question Accessing a list from app web on host site generates access denied
It has the answer I suppose!
In order to benefit from these URLs you would need to pass in the proper Tokens, which can than be retrieved as explained here http://msdn.microsoft.com/en-us/library/jj163816.aspx and http://msdn.microsoft.com/en-us/library/fp179886.aspx
I would even argue that _spPageContextInfo is not to be used in the a SharePoint app (mainly used it in Farm solutions) but rather use the token to build your context properly. Examples for using JSOM available also here http://msdn.microsoft.com/library/jj163201.aspx
_spPageContextInfo can be used in a page in a SharePoint-Hosted app. You will get a "squigly" in the editor because it the _spPageContextInfo object is added to the page dynamically, thus the editor is not aware of it.
Simple example using _spPageContextInfo :
You don't have to necessarily reference a master page in your SharePoint app to get _spPageContextInfo to load.
What is required is the addition of the <asp:ScriptMananger> control to your App or AppPart page. The control has to live in a <form runat="server"> so be sure to add that too.
<body>
<form runat="server">
<asp:ScriptManager id="ScriptManager" runat="server" EnablePageMethods="false" EnablePartialRendering="true" EnableScriptGlobalization="false" EnableScriptLocalization="true" />
<!-- Your code goes here -->
</form>
</body>
