std.json questions

[Dan Olson via Digitalmars-d-learn]

"tired_eyes" <pastuhov85 at gmail.com> writes:
>
> First issue: what is the proper ("idiomatic") way to conver JSONValue
> to the proper types?
>
> Second: what is the proper way of handling boolean values in JSON (how
> to convert JSON_TYPE.TRUE and JSON_TYPE.FALSE to bool)?
>
> Righ now I'm doing is something like this:
>
> string data = readText("file.json");
> JSONValue[string] parsedData = parseJSON(data).object;
> JSONValue[] etities = stateData["entities"].array;
>
> foreach(e; entities) {
>     int x = to!int(e["x"].integer);
>     int y = to!int(e["y"].integer);
>     string texture = stripExtension(e["texture"].str);
>
>     auto isControllable = "isControllable" in e;
>
>     if (isControllable !is null) {
>         if (e["isControllable"].type == JSON_TYPE.TRUE) {
>             isControllable = true;
>         } else {
>             isControllable = false;
>         }
>     }
> }
>
> I think this is ugly and clunky approach, what is the beautiful one?
>
> A brief look at code.dlang.org gives us 7 (!) additional JSON
> libraries. Keeping in mind that D community isn't so huge, I think I'm
> not the only person struggling with std.json. Are there any plans on
> upgrading it?

Hi and welcome to D land.  I see discussions on how std.json needs to be
upgraded.  And it is not well documented.

I tried to progressively simplify the code that was posted to show what
can be done, but keeping the same spirit.  Not necessarily beautiful,
but less verbose code. I did not see a simpler way to deal with bools in
the std.json code.  Others here are experts on idiomatic D, they may
show something much better.

// First , make it work and show all types
void f1()
{
    string data = readText("file.json");
    JSONValue parsedData = parseJSON(data);
    JSONValue entities = parsedData["entities"];

    foreach(size_t index, e; entities) {
        long x = e["x"].integer;
        long y = e["y"].integer;
        string texture = stripExtension(e["texture"].str);

        bool isControllable = false;

        if ("isControllable" in e) {
            if (e["isControllable"].type == JSON_TYPE.TRUE) {
                isControllable = true;
            } else {
                isControllable = false;
            }
        }
        writefln("x %d y %d texture %s isControllable %s",
                 x, y, texture, isControllable);
    }
}

// Next,  let compiler figure types for us
void f2()
{
    auto data = readText("file.json");
    auto parsedData = parseJSON(data);
    auto entities = parsedData["entities"];

    foreach(size_t _, e; entities) {
        auto x = e["x"].integer;
        auto y = e["y"].integer;
        auto texture = stripExtension(e["texture"].str);

        bool isControllable = false;

        if ("isControllable" in e) {
            isControllable = e["isControllable"].type == JSON_TYPE.TRUE;
        }
        writefln("x %d y %d texture %s isControllable %s",
                 x, y, texture, isControllable);
    }
}

// A little simpler isControllable.
void f3()
{
    auto parsedData = readText("file.json").parseJSON;

    foreach(size_t _, e; parsedData["entities"]) {
        auto x = e["x"].integer;
        auto y = e["y"].integer;
        auto texture = stripExtension(e["texture"].str);
        auto isControllable = "isControllable" in e &&
                               e["isControllable"].type == JSON_TYPE.TRUE;
        writefln("x %d y %d texture %s isControllable %s",
                 x, y, texture, isControllable);
    }
}