[Pharo-users] How to write out simple Json?

Tim Mackinnon tim at testit.works
Thu Feb 28 08:45:13 EST 2019


Just to add more flavour to this - it seems quite wordy that we have to do this (or equivalent) to write some config. 

ex := OrderedDictionary new 
	at: 'track' put: 'pharo';
	at: 'language' put: 'smalltalk';
	at: 'exercises' put: (
		OrderedDictionary new
			at: 'slug' put: 'hello';
			at: 'id' put: 55;
			at: 'topics' put: #('a' 'b' 'c');
			yourself );
	yourself.
		
String streamContents: [ :stream |
	(NeoJSONWriter on: (stream)) prettyPrint: true;
	mapInstVarsFor: Association;
	nextPut: ex ].

So I’m still wondering the NeoJSONObjectMapping can do something easy for Association other than simply mapInstVars?


> On 28 Feb 2019, at 13:36, Tim Mackinnon <tim at testit.works> wrote:
> 
> Hi Sven - is there no convenience shortcut we can use in our code to make this less wordy when we are specifying it?
> 
> E.g. the following is very convenient to write - but doesn’t work (as you have $‘ and not $“ )
> 
> ex := { 'track'-> 'pharo'. 
> 	'language' -> 'smalltalk'.
> 	 'exercises' ->
> 		{'slug' -> 'hello'.
> 		'id' -> 55.
> 		'topics' -> #('a' 'b' 'c') }
> 		}.
> 		
> String streamContents: [ :stream |
> 	(STONWriter on: (stream)) prettyPrint: true; 	writeList: ex ].
> 
> I had thought maybe NeoJSON might help and put:
> 
> String streamContents: [ :stream |
> 	(NeoJSONWriter on: (stream)) prettyPrint: true;
> 	"mapInstVarsFor: Association;"
> 	nextPut: ex ].
> 
> But I get the error about missing an association mapping. If I uncomment that bit - I get things like: { "value" : “pharo" },
> 
> So is there a way I can write a simple mapper for Association that will write out the key in a string and the value in a string?
> 
> I’m quite suprised we can’t easily write out fragments of Json in our code in a light weight way? Or do I need to make a proper Config object and then teach it how to map properly such that rather than fiddling with our { x->y } dictionary sugar I do something like:
> 
>  Config new at: ‘id’ is: 123; at: ‘name’ is: ‘Tim’; at: ‘exercises’ is: #(1 2 3).
> 
> And I guess at:is: can do the Association asDictionary thing?
> 
> But I thought Neo might give me something like that, as it must be terribly common?
> 
> Tim
> 
>> On 28 Feb 2019, at 13:16, Sven Van Caekenberghe <sven at stfx.eu> wrote:
>> 
>> STONJSON toString: { #id->1. #name->'tim' } asDictionary.
>> 
>> JSON cannot deal with Associations by themselves.
>> 
>>> On 28 Feb 2019, at 14:05, Tim Mackinnon <tim at testit.works> wrote:
>>> 
>>> I am stumped about how to write out some simple json (for a config file). I didn't think I need Neo, and STONJSON would be fine but it seems like creating items like: 
>>> 
>>> { 'id'-> self id. 'name' -> self name }
>>> 
>>> gives an error about the association. I think you have to do: { ('id'-> self id) asDictionary. ('name' -> self name) asDictionary } everywhere….
>>> 
>>> But when I switch over to NeoJsonWriter it also complains about Assocations too. I just want a simple output like:
>>> { "id" : 12, "name" : "tim” }
>>> 
>>> I thought it was simple to do this? Am I missing something obvious.
>>> 
>>> Tim
>> 
>> 
> 
> 




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