building a simple json tree

[Rikki Cattermole via Digitalmars-d-learn]

On 16/01/2015 1:37 a.m., anonymous wrote:
> On Thursday, 15 January 2015 at 12:10:09 UTC, Rikki Cattermole wrote:
>> On 16/01/2015 12:16 a.m., anonymous wrote:
>>> what's the right syntax for building a JSON tree ? I try to do like in
>>> an AA but the program throw because the Key doesn't exist:
>>>
>>> ---
>>> import std.stdio, std.json;
>>>
>>> void main(string[] args)
>>> {
>>>     struct Foo{
>>>         string a,  b;
>>>         void writeToJson(ref JSONValue target) {
>>>             target["a"] = JSONValue(a);
>>>             target["b"] = JSONValue(b);
>>>         }
>>>     }
>>>
>>>     JSONValue root = parseJSON("{}");
>>>     root["items"] = JSONValue([""]);
>>>
>>>     Foo*[] foos;
>>>     foos ~= new Foo("a1","b1");
>>>     foos ~= new Foo("a2","b2");
>>>
>>>     foreach(foo; foos) {
>>>         root["items"].array.length += 1;
>>>         root["items"].array[$-1] = parseJSON("{}");
>>>         foo.writeToJson(root["items"].array[$-1]);
>>>     }
>>> }
>>> ---
>>
>> import std.stdio, std.json;
>>
>> void main(string[] args)
>> {
>>     struct Foo{
>>         string a,  b;
>>         void writeToJson(ref JSONValue target) {
>>             target["a"] = JSONValue(a);
>>             target["b"] = JSONValue(b);
>>         }
>>     }
>>
>>     JSONValue root = ["items": cast(string[])[]];
>>
>>     Foo[] foos;
>>     foos ~= Foo("a1","b1");
>>     foos ~= Foo("a2","b2");
>>
>>     foreach(foo; foos) {
>>         root["items"].array ~= JSONValue(foo.a);
>>         root["items"].array ~= JSONValue(foo.b);
>>     }
>>
>>     writeln(root.toString());
>> }
>>
>> I would recommend keeping away from std.json. Its an old piece of
>> code, that needs to be replaced.
>> Vibe.d has a much nicer implementation that is really decent. I would
>> recommend that, if you are up to using the build manager dub.
>
> Thx, but actually I initially liked to get an array of object with each
> identifier:
>
> currently it produces:
>
> {"items":["a1","b1","a2","b2"]}
>
> while it'd be more desirable to have
>
> {"items":[{"a":"a1","b":"b1"}, {"a":"a2","b":"b2"}]}
>
> because the reader will test the presence of each the key "a" and "b" in
> each element of "items".
>
> Would it be a complete non-sense to assign an element with
> opIndexAssign(), just like I wrote initially ? I know this is wrong but
> the syntax seemed natural and logic.
> Reading from std.json is straightforward but writing looks a bit messy.

It makes sense to do it. But like I said std.json is rubbish.
Just so you can see why I'm saying vibe.d's json implementation is 
better[0].

[0] 
https://github.com/rejectedsoftware/vibe.d/blob/master/source/vibe/data/json.d#L1670