Re: [Pharo-users] NeoJSON. Allowing null or an object

Nov. 13, 2017

      Hi, 

I have just found the answer for the reader:

-=-=-=-
rectangleJson := '{
  "origin" : null,
  "corner" : null
}'.

(NeoJSONReader on: rectangleJson readStream)
  mapInstVarsFor: Point;
  for: Point do: [ :mapping | 
	mapping allowNil ];
  for: Rectangle do: [ :mapping | 
     (mapping mapInstVar: #origin) valueSchema: Point.
     (mapping mapInstVar: #corner) valueSchema: Point ];
  nextAs: Rectangle.
-=-=-=-

I have an impression that there is a bug in the writer. While the following example works: 

-=-=-=-
String streamContents: [ :stream |
   (NeoJSONWriter on: stream)
		for: Point do: [ :mapping | 
			mapping mapAllInstVars.
			mapping allowNil ];
	   for: Rectangle do: [ :mapping | 
			(mapping mapInstVar: #origin) valueSchema: Point.
			(mapping mapInstVar: #corner) valueSchema: Point ];
      nextPut: Rectangle new ].
-=-=-=-

the following example does not work: 

-=-=-=-
String streamContents: [ :stream |
   (NeoJSONWriter on: stream)
		for: Point do: [ :mapping | 
			mapping mapAllInstVars.
			mapping allowNil ];
	   for: Rectangle do: [ :mapping | 
			(mapping mapInstVar: #origin) valueSchema: Point.
			(mapping mapInstVar: #corner) valueSchema: Point ];
      writeNil: true;
      nextPut: Rectangle new ].
-=-=-=-

What do you think?
Juraj
...
On Nov 13, 2017, at 12:50, Juraj Kubelka <juraj.kubelka@icloud.com> wrote:
Hi,
Please, how should I modify the mapping to be able to parse the following example?
-=-=-=-
rectangleJson := '{
  "origin" : null,
  "corner" : null
}'.
(NeoJSONReader on: rectangleJson readStream)
  mapInstVarsFor: Point;
  for: Rectangle do: [ :mapping | 
     (mapping mapInstVar: #origin) valueSchema: Point.
     (mapping mapInstVar: #corner) valueSchema: Point ];
  nextAs: Rectangle.
-=-=-=-
I receive from a server JSON messages including null values. 
Can we say use Point value schema or null? How?
In the documentation I can see the example:
-=-=-=-
String streamContents: [ :stream |
  (NeoJSONWriter on: stream)
     mapAllInstVarsFor: Point;
     writeNil: true;
     nextPut: Point new ].
-=-=-=-
that produces {"x":null,"y":null}
But I do not see how to apply this for the following example: 
-=-=-=-
String streamContents: [ :stream |
  (NeoJSONWriter on: stream)
     mapAllInstVarsFor: Point;
     for: Rectangle do: [ :mapping | 
       (mapping mapInstVar: #origin) valueSchema: Point.
       (mapping mapInstVar: #corner) valueSchema: Point ];
     writeNil: true;
     nextPut: Rectangle new ].
-=-=-=-
Thanks,
Juraj