canjs/canjs

We CAN build the impossible! https://codepen.io/justinbmeyer/pen/yEGGoK

Chris Gomez

@akagomez

@matthewp We can replace computes on can.Map’s with { type: ‘compute’ }. It’s just not documented yet: bitovi/canjs#1690

opolyo01

@opolyo01

@akagomez Yes, I want something like this. Though, I am not sure I like this whole serialize thing. At first I can do -- map.attr('list') // [1, 2, 3] And after setting new array on the list I get a serialized object. Let me check that this will even auto update in my stache template if I keep serialized version of it

opolyo01

@opolyo01

@matthewp Ok so things with get should be immutable? But I thought the purpose of compute objects to be updated and bindable to a template. If I had a simple can.List outside of Map then everything would just work by updating the list, but what is the process of updating properties under can.Map within define?

Chris Gomez

@akagomez

@opolyo01 The serialize was for demonstration purposes only. Sorry to confuse.

@opolyo01 Here’s a better example: http://jsbin.com/dagefe/2/edit

Chris Gomez

@akagomez

@opolyo01 I think @matthewp Was misinterpretting your question. Computes are the low-level utility that backs can.Map.define. A compute takes a property on set… compute(newVal). So if you unknowingly attempted to set list to something else, like.. map.attr(‘list’, someOtherList), you’ll actually be passing someOtherList to the compute, like this.. map.list(someOtherList), as opposed to map.list = someOtherList. Does that make sense?

opolyo01

@opolyo01

Ok thanks. I found an issue. So get in can.Map define actually being called only if accepts an argument with the new value. I thought, by doing map.attr('list', someOtherList) it will automatically bind to template without me writing the logic in get. So now I have this define: {
dimensionList: {
get: function(filteredDimensions) { instead of define: {
dimensionList: {
get: function() {

Chris Gomez

@akagomez

Can you share your get function? Or maybe summarize it? I wonder if it’s actually necessary for your case.

opolyo01

@opolyo01

get: function(filteredDimensions) {
if(filteredDimensions){
return filteredDimensions;
}
else{//logic for returning original set of dimensions

Basically, I have search that filters for the list of dimensions to show

Chris Gomez

@akagomez

The reason I ask is that get is meant to describe a value that is made up of other values. And since that value is dependent on other values, the get function will only be evaluated when one of those dependent values are changed. In other words, map.attr(‘list’) won’t call get because none of its dependent values have changed. However, when you pass a value to the can.compute like this.. map.attr(‘computedProp’, anotherList) the compute re-evaluates due to the new lastSetVal.

Aside: In your original example you do this.scope.dimensionList(). That’s the incorrect way to read the value. What you should do instead is this.scope.attr(‘dimensionList’).

Okay, so you want an initial list, and you’d like to filter it on keyup?

opolyo01

@opolyo01

yeah

Chris Gomez

@akagomez

Gotcha.

opolyo01

@opolyo01

I am thinking to create a searchTerm compute that would be used inside of get for dimensionList

and then change searchTerm inside of the keyUp event

Chris Gomez

@akagomez

You can define a default with the value method. Provide it a function and it will populate that value for all new instances of the map if one isn’t passed when calling new.. new CustomMap(props).

That’s not a bad idea either.

opolyo01

@opolyo01

I am just trying to figure out where to throw this searchTerm variable

in the past I would simply do this.searchTerm = can.compute("")

but with can.Component.. would it belong in my can.Map

Chris Gomez

@akagomez

Yeah, in your view model.

(or scope if you haven’t made the change)

opolyo01

@opolyo01

Thanks, it works. Now I need to add "change, blur" on top of keyUp event and I am all set

Chris Gomez

@akagomez

Great! In the meantime, I put together this demo: http://jsbin.com/vusuzu/1/edit?js,console

I'm currently working on a much easier way to derive a bound, filtered list from another, so stay tuned: https://github.com/canjs/can-derive

opolyo01

@opolyo01

pretty useful

opolyo01

@opolyo01

Is it the correct way defining the same handler for multiple events

'.search-dimension keyup': this.searchTermChanged,
'.search-dimension change': this.searchTermChanged,
'.search-dimension blur': this.searchTermChanged,

        searchTermChanged: function(el, ev){
            var searchTerm = el.val();
            this.scope.attr('searchTerm', searchTerm);
        },

somehow it only works only if I do -- '.search-dimension keyup': function(el, ev)

Chris Gomez

@akagomez

@opolyo01 'el event

Whoops…

’el event’: ‘handler’

opolyo01

@opolyo01

nice

'.search-dimension keyup': 'searchTermChanged',
'.search-dimension change': 'searchTermChanged',
'.search-dimension blur': 'searchTermChanged',
'.search-dimension search': 'searchTermChanged',

works

Alex

@whitecolor

is is possible to to like this

//refere tho current item as "item", not {.} or this
{{item}}

Alexis Abril

@alexisabril

Any reason why binding to a list internally would be a bad idea?

var Person = can.Map.extend({
  define: {
    items: {
      set: function(val) {
        val.bind('change', console.log);
        return val;
      }
    }
  }
});

I believe we clean up those bindings when a new “items” list is set and when the instance of person is destroyed, but can’t recall offhand #lazyweb

Alexis Abril

@alexisabril

also, should the can.List change event be adding nested properties to the index argument?

var list = new can.List();

list.bind(‘change’, function(ev, index) {});

var foo = new can.Map({ name: ‘foo’ });
list.push(foo); //index is 0, expected

foo.attr(‘name’, ‘bar’); //index is 0.name, I would expect 0

http://jsbin.com/cuqato/1/edit?js,output

Chris Gomez

@akagomez

@alexisabril For your second example (“0.name”), that seems right to me. Since the “name” property changed on the item in the “0” index position.

Isn’t that argument called “attr”, not “index”? Context matters.

Alexis Abril

@alexisabril

@akagomez that’s true, we do document “index” as where the change took place. perhaps my issue is with calling it “index” in the docs: “0.name” isn’t the index

http://canjs.com/docs/can.List.prototype.attr.html#section_Events

Chris Gomez

@akagomez

Yeah. Understandable. In a simple list, “attr” would look like “index”.

Alexis Abril

@alexisabril

What’s everyone’s approach to abstracting out arbitrary data from a model?

For instance, suppose a user model:

{ id: 0, name: ‘Alexis’ }

However, in the template we would also want:

{ isEditing: false }

You wouldn’t want to add that attribute directly to the model as it has no benefit being sent back to the server(just view noise).

The elegant answer is inheritable defines(I think), but I’m curious what everyone’s approach has been thus far.

opolyo01

@opolyo01

@alexisabril I just usually have some _.map somewhere in controller code that being passed to the template. It is probably better to abstract in the UI model class like you do.

Well, I am currently stuck with another issue that might not be can.js related, but part of can.js application that uses clientState

$.extend(true, {}, this.constructor.defaults, overrides)
jquery.js:300 Uncaught RangeError: Maximum call stack size exceeded
at Function.jQuery.extend.type (http://localhost:8126/bower_components/jquery/dist/jquery.js:300:16)

Has anyone ever had this issue? I simply extending two objects.. overrides has a property of clientState that is pretty big in size for some states

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