Transactions

[emilbayes]

Would it be possible to implement transactions like in observ-array? When looking through the code I see var currentTransaction = NO_TRANSACTION, but I don't find any documentation or tests on how to use transactions (if at all possible).

I'd be happy to do a PR if I can get some guidance on where to start :)

[nrw]

Transactions are implemented in the sense that doing this:

varhashInstance.set({food: 'banana'})

Has the same effect as doing this:

varhashInstance.food.set('banana')

Adding a transaction function would probably be a good addition and not a complex one. it will be much like in observ-array. shallow copy the state and pass the raw copy to the transaction function. after modifications, call observVarhash.set(rawCopy). We may want to wrap the raw object so the put, get, etc. interface can be retained in the transaction function.

That's the route I'd go unless @Raynos has another vision.

[Raynos]

I didnt design the transaction interface.

It's mostly useful for doing bulk operations on an array; for example bulk addition or re ordering.

It still makes sense to do bulk operations on a hash; for example bulk addition.

I would recommend that the interface just be that you are given a raw copy and are expected to mutate it synchronously in the transaction function.

Adding methods like put & get seems unnecessary.

[nrw]

@emilbayes i think that should be enough for you to put together a PR. :)

[mpal9000]

Hello, I'm using mercury and I want to ask if it is possible to completely replace a "varhash" (or its propeties) that lives inside an observ-struct, ie. hg.state(). I have a "varhash" grid which contains "struct" cells. I wan't to be able to reset that grid, by replacing all cells in a single state update, ie. when undoing with mercury's "time-travel", I want to get back the previous grid in one step. The bulk update that you are discussing here could be enough, but maybe there is a more performant way, instead of iterating through the "varhash" grid.

off topic: Is there a possibility to add some iteration methods to "varhash". Mercury suggests to use this lib instead of observ-array and that is what I'am doing. But I'm missing the iteration style of an array.

[nrw]

@mpal9000 Does varhash.set({newData: "for this instance"}) do what you need? it's in the test here. Otherwise, if you provide a failing test case, we can better help you.

You should see varhash more like an object than an array. you can do this, just like you would in an object:

Object.keys(varhashInstance).map(function (key) {
  var val = varhashInstance[key]
  // do something with val
})

Does that do the job for you?

[mpal9000]

@nrw Hi, I see varhash like a key-value strore and it is nice, although I would prefer having also a working array structure. Here is an example that describes better the problem: https://github.com/mpal9000/mercury-example-1 (see the comments inside ./index.js)