[Opensim-dev] Add a JsonTestStore() for the JSON store module?

[Justin Clark-Casey]

Thanks Mic.  Sorry I wasn't around earlier - schedule has gone massively late again (and I'm probably offline thurs).

I'm not an LSL expert, but I think the classic 'LSL' way to do this would be to return a strided list [1].

Maybe something like

JsonGetValues(key storeID, string path):list
JsonGetValuesJson(key storeID, string path):list

So

list stridedVals = JsonGetValues(storeID, "foo[*].bar");

to get something like

["foo[0].bar", "hello", "foo[1].bar", "world", ... ]

Then one can use functions like llList2ListStrided to get just the values as desired, e.g.

list result_a = llList2ListStrided(stridedVals, 0, -1, 2);
// result_a == [ "hello", "world" ]

In this way, maybe one could even return the deeper structure by listing the full key for each value rather than the 
return serialized approach of the *Json() functions.  Maybe this could be signalled as via an optional constant int 
flags field (in the same LSL way that things like osNpcCreate() take options).

Strided lists are pretty horrible but at least people are familiar with them and there are various functions to help 
with handling them.  I guess it's the only way to get any semblance of nested data structures in LSL.

Also, a couple of other questions, which might just be due to my ignorance of not having looked at the code deeply 
enough yet.

* I see there are many parallel *Json methods such as JsonGetValueJson().  I presume the natural way to parse serialized 
json returned from those (if one wanted) would be to temporarily create a store and then remove it?

* Is the 'JPath' implementation the one at [2] or perhaps the one at [3] or something else entirely?  How much of these 
'specifications' is currently implemented?

[1] http://wiki.secondlife.com/wiki/Category:LSL_List#Strided_lists
[2] http://goessner.net/articles/JsonPath/
[3] http://projects.plural.cc/projects/jsonij/wiki/JPath


On 30/01/13 22:48, Mic Bowman wrote:
> Done.
>
> On Wed, Jan 30, 2013 at 8:57 AM, Mic Bowman <cmickeyb at gmail.com <mailto:cmickeyb at gmail.com>> wrote:
>
>     I think that would be very useful. I can add it this afternoon, if you don't beat me to it.
>
>     When I wrote the interface to the Json store, I modeled the path expansion after JQuery interface. However, I'm
>     finding that really challenging to use for iterating through an array of values. Right now, I use osFormatString to
>     create the path dynamically. For example:
>
>     integer i = 0;
>     while (i < 10)
>     {
>          string p = osFormatString("foo[{0}].bar",[i]); // create path "foo[0].bar"
>          string v = JsonGetValue(storeID,p);
>     }
>
>     If you have any suggestions for a construct that would make the iteration cleaner, I would be very interested. I've
>     bounced around (and written some test code) for taking a list (the components of the path) as an argument, but
>     constructing the list is no easier than constructing the string. I've also poked around with creating store handles
>     that point into an existing store (so you resolve the path "foo" into a store handle then iterate at the top level).
>     Again, the code to walk through the structure is still excessively complex.
>
>     --mic
>
>
>
>
>     On Tue, Jan 29, 2013 at 10:03 PM, Justin Clark-Casey <jjustincc at googlemail.com <mailto:jjustincc at googlemail.com>> wrote:
>
>         Hi Mic.  Whilst looking through these functions tonight, it struck me that there doesn't appear to be a way to
>         tell if a certain JSON store still exists, as identified by its key.
>
>         Do you think it would be appropriate to add a function for that?  Perhaps JsonTestStore(), which is in keeping
>         with JsonTestPath()?
>
>         --
>         Justin Clark-Casey (justincc)
>         OSVW Consulting
>         http://justincc.org
>         http://twitter.com/justincc
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-- 
Justin Clark-Casey (justincc)
OSVW Consulting
http://justincc.org
http://twitter.com/justincc