Intersystems Cache - Can Python be used to directly access a global or only classes exposed as sql tables?

Question

Can the python interface be used to directly access and iterate through an intersystems cache global, or does python simply expose the same "tables" I see when I use a linked server or ODBC Connection?

Answer 1

If you want to directly access globals you can create a stored procedure that will do so. You should consider the security implications before you do this - it will expose all data in the global to anyone with ODBC access.

Here is an example of a stored procedure that returns the values of up to 9 global subscripts, plus the value at that node. You can modify it pretty easily if you need to.

Query OneGlobal(GlobalName As %String) As %Query(ROWSPEC = "NodeValue:%String,Sub1:%String,Sub2:%String,Sub3:%String,Sub4:%String,Sub5:%String,Sub6:%String,Sub7:%String,Sub8:%String,Sub9:%String") [SqlProc]
{
}

ClassMethod OneGlobalExecute(ByRef qHandle As %Binary, GlobalName As %String) As %Status
{
    S qHandle="^"_GlobalName
    Quit $$$OK
}

ClassMethod OneGlobalClose(ByRef qHandle As %Binary) As %Status [ PlaceAfter = OneGlobalExecute ]
{
    Quit $$$OK
}

ClassMethod OneGlobalFetch(ByRef qHandle As %Binary, ByRef Row As %List, ByRef AtEnd As %Integer = 0) As %Status [ PlaceAfter = OneGlobalExecute ]
{

    S Q=qHandle  
    S Q=$Q(@Q)  b  
    I Q="" S Row="",AtEnd=1 Q $$$OK
    S Depth=$QL(Q)
    S $LI(Row,1)=$G(@Q)
    F I=1:1:Depth S $LI(Row,I+1)=$QS(Q,I)
    F I=Depth+1:1:9 S $LI(Row,I+1)=""
    S AtEnd=0
    S qHandle=Q
    Quit $$$OK
}

To access this from python you might use (with pyodbc):

import pyodbc
import win32com.client
import urllib2

class CacheOdbcClient:

    connectionString="DSN=MYCACHEDSN"

    def __init__(self):
        pass

    def getGlobalAsOverlyLargeList(self):
        connection=pyodbc.connect(self.connectionString)
        cursor=connection.cursor()
        cursor.execute("call MyPackageName.MyClassName_OneGlobal ?","MYGLOBAL")
        list=[]
        for row in cursor :
            list.append((row.NodeValue,row.Sub1,row.Sub2,row.Sub3,row.Sub4,row.Sub5,row.Sub6,row.Sub7,row.Sub8,row.Sub9))
        return list

Answer 2

There are 2 types of Cache access in Python -- ODBC connection (you will see your tables) and Python binding (you will see your classes). You may create a class which will iterate through Cache globals if you want and then use it from Python binding. There is a documentation on Python binding in Cache. http://docs.intersystems.com/cache20111/csp/docbook/DocBook.UI.Page.cls?KEY=GBPY