Robert Cemper · Mar 24 3m read


This package offers a utility to export an XLarge Global into a JSON object file and to show
or import it again. In a previous example, this all was processed in memory. But if this is a
large Global you may either experience <MAXSTRING> or an <STORE>  error
if the generated JSON structure exceeds available memory.

Academic refers to the structure created.

  • each node of the Global including the top node is represented as a JSON object
  • {"node":<node name>,"val":<value stored>,"sub":[<JSON array of subscript objects>]}
  • value and subscript are optional but one of them always exists for a valid node
  • the JSON object for the lowest level subscript has only value but no further subscript.

So this is basically a 1:1 image of your global and it's exported to a file (default: gbl.json)
In addition to the export, a show method displays the generated file.
The tricky part is the import from file. It is a customize JSON parser as all others just
operate in memory. this fails with a reasonable-sized Global
(eg. ^oddDEF with ~ 1.7 million nodes takes ~ 78MB JSON file.)


Make sure you have git and Docker desktop installed.


Clone/git pull the repo into any local directory

git clone    

Run the IRIS container with your project:

docker-compose up -d --build

How to Test it

This is the pre-loaded Global ^dc.MultiD for testing.

There are 3 methods available

  • ClassMethod export(gref As %String = "^%", file = "gbl.json") As %String file = 0 >>> display to terminal
  • ClassMethod show(file = "gbl.json") As %String
  • ClassMethod import( file = "gbl.json", test = 0) As %String test = 1 >>> load into a PPG

Open IRIS terminal

$ docker-compose exec iris iris session iris

USER>write ##class(dc.GblToJSON.XLA).export("^dc.MultiD")
File gbl.json created

USER>write ##class(dc.GblToJSON.XLA).export("^dc.MultiD",0)
,"val":"$lb(\"Braam,Ted Q.\",51353)"
---  truncated ---

USER>>write ##class(dc.GblToJSON.XLA).show()
,"val":"$lb(\"Braam,Ted Q.\",51353)"
---  truncated ---  

validated JSON object

Now we want to verify the load function as a test into a PPG

USER>write ##class(dc.GblToJSON.XLA).import(,1)
Global ^||dc.MultiD loaded

USER>zwrite ^||dc.MultiD
^||dc.MultiD(1)=$lb("Braam,Ted Q.",51353)
^||dc.MultiD(2)=$lb("Klingman,Uma C.",62459)
^||dc.MultiD(3)=$lb("Goldman,Kenny H.",45831)


Code Quality


Do not wonder about some strange code constructs.
They were required as CodeQuality neither understands the NEW command, nor the scope of %variables  !   sad


Online Demo Terminal
Online Demo SMP

Previous article in DC

0 204
Discussion (1)1
Log in or sign up to continue