rust library: how to get node value?

[gabriel-v]

In rust, using this as a library, we got get(), put(), on(), map(), but no val().

There's no way to get the value from a node, other than subscribing to it and overwriting something else, thus losing the initial value.

[gabriel-v]

First problem was that one-level paths don't work, thanks for the test comment.

This doesn't work:

db.get("x").put("Hello World!".into());
let mut sub = db.get("x").on();
println!("{:?}", sub.recv().await.unwrap());

This works:

db.get("x").get("y").put("Hello World!".into());
let mut sub = db.get("x").get("y").on();
println!("{:?}", sub.recv().await.unwrap());

Nicely enough, GUN itself documents this: https://gun.eco/docs/API#unexpected-behavior

You cannot save primitive values at the root level.

Gun().put("oops"); // error
Gun().get("odd").put("oops"); // error

Would be nice if we had those errors too.

With this change, on() gives out the local value before streaming new ones - this helps our case.

The next question is that of missing values - in gun.js, once() gives you back the undefined in whatever wait interval you set (default 99ms).

    let mut sub = db.get("x").get("missing6").on();
    println!("{:?}", timeout(Duration::from_millis(66), sub.recv()).await);

This gives out Err(Elapsed(())) which would be our undefined.

This approach now has a couple of problems:

• it probably needs debounce, say the docs
• it shouldn't do the debounce when the value is already completely loaded

Looking at once() in on.js - we can see the "debounce" there is indeed a timeout that keeps resetting itself, reading from that Gun.get which is actually Gun.on. The "debounce" is skipped when the value you get back passes Gun.valid(data) - and that just checks if we're dealing with a primitive (null, str, int) or relation.

But - looking at what is actually implemented:

db.get("x").get("y").get("z").put("Hello World 1!".into());
db.get("x").get("y").get("t").put("Hello World 2!".into());
let mut sub = db.get("x").get("y").on();
println!("{:?}", timeout(Duration::from_millis(66), sub.recv()).await);

// prints out Ok(Ok(Link("x/y")))

Whereas gun.js returns the reconstructed object at that point:

gun.get('x').get('y').get('z').put('a');
gun.get('x').get('y').get('t').put('b');
gun.get('x').get('y').once(console.log);
Object { _: {…}, z: "a", t: "b" }

Since on() on some "object" value returns only a link to itself and not any children, I don't think we need to implement the debounce.

PR here: #20

I guess I'll look at listing children next