topic Re: deferred action for graphic in Web AppBuilder Custom Widgets Questions

deferred action for graphic

LefterisKoumis — Sun, 12 Dec 2021 09:21:18 GMT

What is the best way to wait for this graphic to load?

Line 1, 2 and 3 are loaded (See console.log)

But line 6 suggest not yet, everything is null (see console.log)

I tried

all(features).then(function (results) {

but it didn't work...

Thanks.

console.log(layerSettings.options.geom)
console.log(layerSettings.options.symbol)
console.log(layerSettings.options.attr)
var graphic = new esri.Graphic(layerSettings.options.geom, layerSettings.options.symbol, layerSettings.options.attr);
features.push(graphic)
console.log(features))‍‍‍‍‍‍

Re: deferred action for graphic

LefterisKoumis — Sun, 12 Dec 2021 09:21:20 GMT

I modified the code to use promise but still line 16 in the console.log shows the i symbol which means that the graphic was still not ready!

console.log(layerSettings.options.geom)
console.log(layerSettings.options.symbol)
console.log(layerSettings.options.attr)
var graphic = new esri.Graphic();
promise1 = graphic.setGeometry(layerSettings.options.geom)
promisesArray.push(promise1)
promise2 = graphic.setAttributes(layerSettings.options.attr)
promisesArray.push(promise2)
promise3 = graphic.setSymbol(layerSettings.options.symbol)
promisesArray.push(promise3)

                    
var handleAllPromises = Promise.all(promisesArray);
handleAllPromises.then(function (values) {
    features.push(graphic)
    console.log(graphic)                        
    console.log("All the promises are resolved", values);
});
handleAllPromises.catch(function (reason) {
     console.log("One of the promises failed with the following reason", reason);
 });‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: deferred action for graphic

RobertScheitlin__GISP — Thu, 18 Oct 2018 13:09:27 GMT

Lefteris,

The setGeometry, setAttributes and setSymbol all return a graphic Not a deferrred (promise) so you can not use them as promises like you are attempting to. Your timing issue seems to be that layerSettings.options is not ready when you are attempting to use it. You need to figure out how to wait for this object. How exactly is this object being created?

Re: deferred action for graphic

LefterisKoumis — Thu, 18 Oct 2018 16:31:02 GMT

Understood. The layerSettings is an object created from reading a local json file. However, it can have a lot of elements depending the polygon that is stored in the file. So, the layerSettings.options needs to be complete before it can be used.

Re: deferred action for graphic

RobertScheitlin__GISP — Thu, 18 Oct 2018 16:36:10 GMT

Lefteris,

So it sounds like you need to put the json reading portion inside a deferred.

Re: deferred action for graphic

LefterisKoumis — Sun, 12 Dec 2021 09:21:23 GMT

I located the problem in JSON.parse. The console.log still shows the i symbol. Perhaps the sessionsString is too large to be parsed?

sessionsToLoad = JSON.parse(sessionsString);
                    
console.log(sessionsToLoad);‍‍‍

Re: deferred action for graphic

RobertScheitlin__GISP — Fri, 19 Oct 2018 12:48:33 GMT

Lefteris,

Since the JSON.parse does not return a deferred or any indication when it is done reading you will have to make a loop that checks for the json to be done pasing by looking at the result sessionsToLoad and looking for a particular hasOwnProperty or just add a setTimeout.

Re: deferred action for graphic

LefterisKoumis — Sun, 12 Dec 2021 09:21:25 GMT

THis is proven harder than I thought. I did just that, added a property at the end and run a timeout function until it reads that last property but still I get the i symbol!

What I don't understand is that JSON.parse() is a synchronous method, meaning that once it's called it will execute fully, before code execution continues. Why the console.log is not complete?

sessionsToLoad = JSON.parse(sessionsString);
                    
console.log(sessionsToLoad);

Re: deferred action for graphic

RobertScheitlin__GISP — Tue, 23 Oct 2018 12:28:27 GMT

Lefteris,

Sorry I don't have an answer to that.

Re: deferred action for graphic

LefterisKoumis — Wed, 24 Oct 2018 00:21:44 GMT

On another website, it was stated that examining objects via console.log happens in an asynchronous manner. That explains it.

Re: deferred action for graphic

RobertScheitlin__GISP — Wed, 24 Oct 2018 12:43:25 GMT

So are you still having issues then?