Meteor infinite loop with Session variables - session

i'm rather new to Meteor and have a problem, where can't figure out how to solve it.
I want to store dates in a collection. I can pickup the place of the meeting using google maps, which gives me a String with the coordinates.
I reverse geocode the coordinates with jaymc:google-reverse-geocode which is basically working (i can console.log the results).
When using Session variables i can output the result, but they keep changing itself. The entrys get there result, then first and second entry change their result, then they change again and so on.
I tried to use ReactiveVar and ReactiveDict but with no result. I can't get any results returned from the reverseGeocode function.
Here's the code:
{{#each termine}}
<div class="listTermine">
<p class="title">{{title}}</p>
<p class="desc">{{desc}}</p>
<p class="location">{{getAddress}}</p>
<p class="dates">
<span class="glyphicon glyphicon-time" aria-hidden="true"></span>
{{formatDate startDate}} bis {{formatDate endDate}}
</p>
</div>
{{/each}}
Template.showTermine.helpers({
getAddress: function() {
var locArray = Termine.findOne({
"title": this.title
}, {
fields: {
locations: 1
}
});
latlngArray = locArray.locations.toString();
var latlong = latlngArray.split(",");
var lat = latlong[0];
var lng = latlong[1];
reverseGeocode.getLocation(lat, lng, function(location) {
Session.set('location', reverseGeocode.getAddrStr());
})
// commented out to prevent infinite loop
//return Session.get('location');
}
});

this is because a Reactive variable (like a Session variable) will cause the whole function it is included in to re-run each time it is changed.
So here you have the Session.set() in the same function as the Session.get(), so it will re-run the getAddress function each time Session.set() is called, which will re-run the thing in a loop.
Since you're returning the result in the same function, you really don't need a Session variable at all here:
you can simply:
reverseGeocode.getLocation(lat, lng, function(location) {
return reverseGeocode.getAddrStr();
})
if this doesn't work (because you're doing an asynchronous call to .getLocation), then you should do this call somewhere else
The best place to do this would be in the Template.mytemplate.onCreated() event
Template.showTermine.onCreated(function() {
var locArray = Termine.findOne({
"title": this.title
}, {
fields: {
locations: 1
}
});
latlngArray = locArray.locations.toString();
var latlong = latlngArray.split(",");
var lat = latlong[0];
var lng = latlong[1];
reverseGeocode.getLocation(lat, lng, function(location) {
Session.set('location', reverseGeocode.getAddrStr());
})});
Template.showTermine.helpers({
"getAddress": function() {
return Session.get("location");
}
});

The set is called inside the callback which will execute after the helper has returned the get already, this mean when it sets the variable the helper gets invalidated because of the change in the session value and reruns.
Couple of possible fixes:
Move code to set the var into the onCreated or onRendered methods and remove everything bar the return from your helper
Or
Ensure the session var is created as a null value initially and then add an if check to look at the value of the var before attempting to call the location service or set the var.
Reactive vars are defo the right way to go over sessions for repeated templates here to avoid namespace collisions in session and the same advice should work for reactive vars or sessions vars. Just avoid setting and getting anything reactive in the same helper without some checks to see if it is needed

Related

Nightwatch .execute() how to pass parameter to execute function, is it possible?

Please be patient - I am a beginner in programming. Tester for long time but programming is not my domain.
My test is:
from the backend I get some list with some element (e.g. 5 text strings)
I click some element on page which displayed those 5 elements (of course I don't know if listed elements are correct or not)
I need to check if list of elements displayed on ui is the list received from backend
Problem:
I cannot access the elements by Nightwatch api css selector, at least I could not manage (Angular app) to do it with Nightwatch
I found I could do it with .execute()
My code is (failing):
browser
.click(selector.HEADER.APPS_GRID, function () {
for (var app in appsList) {
let appShortName = appsList[app].shortName
let appLongName = appsList[app].longName
let appUrl = appsList[app].url
let appVisibility = appsList[app].visibility
browser.execute(function(app){
var appShortNameDisplayed = document.getElementsByClassName('logo-as-text')[app].innerText
var appLongNameDisplayed = document.getElementsByClassName('app-name')[app].innerText
return [appShortNameDisplayed, appLongNameDisplayed]
}, function(result){
console.log(result.value[0])
})
}
})
It fails in lines:
var appShortNameDisplayed = document.getElementsByClassName('logo-as-text')[app].innerText
var appLongNameDisplayed = document.getElementsByClassName('app-name')[app].innerText
unfortunately I have to make query with [app] - iterating by elements of object. If I skip [app].innerText I get some data like element-6066-11e4-a52e-4f735466cecf instead of text values displayed on page
I get error:
Error while running .executeScript() protocol action: TypeError: document.getElementsByClassName(...)[app] is undefined
Is it possible to pass the "app" param (counter) to the document query?
Or is it the way I have to make one query that will return as many data as necessary and then handle data returned in this block
function(result) {
console.log(result.value[0])
})
The fragment of html page is
<div _ngcontent-c8="" class="ep-app-icon mt-auto mb-auto text-center logo-as-text"> XXX </div>
... and I need to get this "XXX" text.
As your own comment suggests, there is an args argument to .execute that is an array. The array elements will be the arguments in the function passed to execute.
See https://nightwatchjs.org/api/commands/#execute
.executeAsync(function(){
var buttons=document.getElementsByTagName('button');
buttons[2].click();
return buttons;
},[],function(result){
console.log('done')
})
Try Async it works for sure

Is there a way to run code after knockoutjs render only knowing the binding context?

I'm working on a module in a CMS' backend. I'm trying to 'hook in' to their knockout bindings and run code when they are finished rendering. So far I've had no luck.
I have however, attached to the different data-components and obtained knockout data.
I've had many failed attempts, but so far, I have this which is returning a binding context.
var bindingContext = ko.contextFor(jQuery('div[data-component="customer_form.areas"]').get(0));
Does anyone know of a way I can use this to somehow attach an observer to watch for the rendering to finish? I'll admin, I'm new to knockout. I'm not creating the view models, nor the templates. I can't add the afterRender to the template like I think should be done.
Like you said, this should be done using afterRender. All other methods feel hacky, because you'll never know when knockout will re-render (parts of) the ui.
I can't think of a reason why you'd need such a work around, but who am I to judge..
The only approach I can think off, is to use the MutationObserver. Here's an example:
var bindingContextElement = document.querySelector("ul");
var renderThrottle = 300;
var renderCycle = null;
var onRenderComplete = function() {
var pre = document.createElement("pre");
var msg = new Date().toLocaleString() + ": finished rendering";
pre.appendChild(document.createTextNode(msg));
document.body.appendChild(pre);
}
// Observe mutations to element, call onRenderComplete after 300ms of no mutations
var observer = new MutationObserver(function(mutations) {
clearTimeout(renderCycle);
renderCycle = setTimeout(onRenderComplete, renderThrottle);
});
var config = {
childList: true
};
observer.observe(bindingContextElement, config);
ko.applyBindings({
items: ko.observableArray([1, 2, 3])
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<ul data-bind="foreach: items">
<li data-bind="text: $data"></li>
</ul>
<button data-bind="click: function() { items.push(items().length + 1)}">add</button>
This code listens to any mutations in the <ul> element, which is controlled by knockout. Once changes start happening to the element or its children, it attempts to log a "Rendered" message. It's only allowed to log this message if there are no further changes for 300ms.
Have a look at the docs to determine your config object and which elements to watch... And please keep in mind that things might get out of hand if stuff gets more complicated than this example...

Calling a function when ng-repeat has finished

What I am trying to implement is basically a "on ng repeat finished rendering" handler. I am able to detect when it is done but I can't figure out how to trigger a function from it.
Check the fiddle:http://jsfiddle.net/paulocoelho/BsMqq/3/
JS
var module = angular.module('testApp', [])
.directive('onFinishRender', function () {
return {
restrict: 'A',
link: function (scope, element, attr) {
if (scope.$last === true) {
element.ready(function () {
console.log("calling:"+attr.onFinishRender);
// CALL TEST HERE!
});
}
}
}
});
function myC($scope) {
$scope.ta = [1, 2, 3, 4, 5, 6];
function test() {
console.log("test executed");
}
}
HTML
<div ng-app="testApp" ng-controller="myC">
<p ng-repeat="t in ta" on-finish-render="test()">{{t}}</p>
</div>
Answer:
Working fiddle from finishingmove: http://jsfiddle.net/paulocoelho/BsMqq/4/
var module = angular.module('testApp', [])
.directive('onFinishRender', function ($timeout) {
return {
restrict: 'A',
link: function (scope, element, attr) {
if (scope.$last === true) {
$timeout(function () {
scope.$emit(attr.onFinishRender);
});
}
}
}
});
Notice that I didn't use .ready() but rather wrapped it in a $timeout. $timeout makes sure it's executed when the ng-repeated elements have REALLY finished rendering (because the $timeout will execute at the end of the current digest cycle -- and it will also call $apply internally, unlike setTimeout). So after the ng-repeat has finished, we use $emit to emit an event to outer scopes (sibling and parent scopes).
And then in your controller, you can catch it with $on:
$scope.$on('ngRepeatFinished', function(ngRepeatFinishedEvent) {
//you also get the actual event object
//do stuff, execute functions -- whatever...
});
With html that looks something like this:
<div ng-repeat="item in items" on-finish-render="ngRepeatFinished">
<div>{{item.name}}}<div>
</div>
Use $evalAsync if you want your callback (i.e., test()) to be executed after the DOM is constructed, but before the browser renders. This will prevent flicker -- ref.
if (scope.$last) {
scope.$evalAsync(attr.onFinishRender);
}
Fiddle.
If you really want to call your callback after rendering, use $timeout:
if (scope.$last) {
$timeout(function() {
scope.$eval(attr.onFinishRender);
});
}
I prefer $eval instead of an event. With an event, we need to know the name of the event and add code to our controller for that event. With $eval, there is less coupling between the controller and the directive.
The answers that have been given so far will only work the first time that the ng-repeat gets rendered, but if you have a dynamic ng-repeat, meaning that you are going to be adding/deleting/filtering items, and you need to be notified every time that the ng-repeat gets rendered, those solutions won't work for you.
So, if you need to be notified EVERY TIME that the ng-repeat gets re-rendered and not just the first time, I've found a way to do that, it's quite 'hacky', but it will work fine if you know what you are doing. Use this $filter in your ng-repeat before you use any other $filter:
.filter('ngRepeatFinish', function($timeout){
return function(data){
var me = this;
var flagProperty = '__finishedRendering__';
if(!data[flagProperty]){
Object.defineProperty(
data,
flagProperty,
{enumerable:false, configurable:true, writable: false, value:{}});
$timeout(function(){
delete data[flagProperty];
me.$emit('ngRepeatFinished');
},0,false);
}
return data;
};
})
This will $emit an event called ngRepeatFinished every time that the ng-repeat gets rendered.
How to use it:
<li ng-repeat="item in (items|ngRepeatFinish) | filter:{name:namedFiltered}" >
The ngRepeatFinish filter needs to be applied directly to an Array or an Object defined in your $scope, you can apply other filters after.
How NOT to use it:
<li ng-repeat="item in (items | filter:{name:namedFiltered}) | ngRepeatFinish" >
Do not apply other filters first and then apply the ngRepeatFinish filter.
When should I use this?
If you want to apply certain css styles into the DOM after the list has finished rendering, because you need to have into account the new dimensions of the DOM elements that have been re-rendered by the ng-repeat. (BTW: those kind of operations should be done inside a directive)
What NOT TO DO in the function that handles the ngRepeatFinished event:
Do not perform a $scope.$apply in that function or you will put Angular in an endless loop that Angular won't be able to detect.
Do not use it for making changes in the $scope properties, because those changes won't be reflected in your view until the next $digest loop, and since you can't perform an $scope.$apply they won't be of any use.
"But filters are not meant to be used like that!!"
No, they are not, this is a hack, if you don't like it don't use it. If you know a better way to accomplish the same thing please let me know it.
Summarizing
This is a hack, and using it in the wrong way is dangerous, use it only for applying styles after the ng-repeat has finished rendering and you shouldn't have any issues.
If you need to call different functions for different ng-repeats on the same controller you can try something like this:
The directive:
var module = angular.module('testApp', [])
.directive('onFinishRender', function ($timeout) {
return {
restrict: 'A',
link: function (scope, element, attr) {
if (scope.$last === true) {
$timeout(function () {
scope.$emit(attr.broadcasteventname ? attr.broadcasteventname : 'ngRepeatFinished');
});
}
}
}
});
In your controller, catch events with $on:
$scope.$on('ngRepeatBroadcast1', function(ngRepeatFinishedEvent) {
// Do something
});
$scope.$on('ngRepeatBroadcast2', function(ngRepeatFinishedEvent) {
// Do something
});
In your template with multiple ng-repeat
<div ng-repeat="item in collection1" on-finish-render broadcasteventname="ngRepeatBroadcast1">
<div>{{item.name}}}<div>
</div>
<div ng-repeat="item in collection2" on-finish-render broadcasteventname="ngRepeatBroadcast2">
<div>{{item.name}}}<div>
</div>
The other solutions will work fine on initial page load, but calling $timeout from the controller is the only way to ensure that your function is called when the model changes. Here is a working fiddle that uses $timeout. For your example it would be:
.controller('myC', function ($scope, $timeout) {
$scope.$watch("ta", function (newValue, oldValue) {
$timeout(function () {
test();
});
});
ngRepeat will only evaluate a directive when the row content is new, so if you remove items from your list, onFinishRender will not fire. For example, try entering filter values in these fiddles emit.
If you’re not averse to using double-dollar scope props and you’re writing a directive whose only content is a repeat, there is a pretty simple solution (assuming you only care about the initial render). In the link function:
const dereg = scope.$watch('$$childTail.$last', last => {
if (last) {
dereg();
// do yr stuff -- you may still need a $timeout here
}
});
This is useful for cases where you have a directive that needs to do DOM manip based on the widths or heights of the members of a rendered list (which I think is the most likely reason one would ask this question), but it’s not as generic as the other solutions that have been proposed.
I'm very surprised not to see the most simple solution among the answers to this question.
What you want to do is add an ngInit directive on your repeated element (the element with the ngRepeat directive) checking for $last (a special variable set in scope by ngRepeat which indicates that the repeated element is the last in the list). If $last is true, we're rendering the last element and we can call the function we want.
ng-init="$last && test()"
The complete code for your HTML markup would be:
<div ng-app="testApp" ng-controller="myC">
<p ng-repeat="t in ta" ng-init="$last && test()">{{t}}</p>
</div>
You don't need any extra JS code in your app besides the scope function you want to call (in this case, test) since ngInit is provided by Angular.js. Just make sure to have your test function in the scope so that it can be accessed from the template:
$scope.test = function test() {
console.log("test executed");
}
A solution for this problem with a filtered ngRepeat could have been with Mutation events, but they are deprecated (without immediate replacement).
Then I thought of another easy one:
app.directive('filtered',function($timeout) {
return {
restrict: 'A',link: function (scope,element,attr) {
var elm = element[0]
,nodePrototype = Node.prototype
,timeout
,slice = Array.prototype.slice
;
elm.insertBefore = alt.bind(null,nodePrototype.insertBefore);
elm.removeChild = alt.bind(null,nodePrototype.removeChild);
function alt(fn){
fn.apply(elm,slice.call(arguments,1));
timeout&&$timeout.cancel(timeout);
timeout = $timeout(altDone);
}
function altDone(){
timeout = null;
console.log('Filtered! ...fire an event or something');
}
}
};
});
This hooks into the Node.prototype methods of the parent element with a one-tick $timeout to watch for successive modifications.
It works mostly correct but I did get some cases where the altDone would be called twice.
Again... add this directive to the parent of the ngRepeat.
Very easy, this is how I did it.
.directive('blockOnRender', function ($blockUI) {
return {
restrict: 'A',
link: function (scope, element, attrs) {
if (scope.$first) {
$blockUI.blockElement($(element).parent());
}
if (scope.$last) {
$blockUI.unblockElement($(element).parent());
}
}
};
})
Please have a look at the fiddle, http://jsfiddle.net/yNXS2/. Since the directive you created didn't created a new scope i continued in the way.
$scope.test = function(){... made that happen.

HTML data from multiple ajax requests to javascript array

I'm trying to pre-load some html content using AJAX and jQuery. The AJAX callback function adds the data to an associative array. I'm fine if I do each request individually:
var contentArray = new Object();
var urlA = "includes/contentA.php";
var urlB = "includes/contentB.php";
var urlC = "includes/contentC.php";
$.get(urlA, function(htmlA) {
contentArray["A"] = htmlA;
});
$.get(urlB, function(htmlB) {
contentArray["B"] = htmlB;
});
$.get(urlC, function(htmlC) {
contentArray["C"] = htmlC;
});
Since I am likely to have a few of these (more than three), I tried to do it a for loop:
var contentArray = new Object();
var pages = new Object();
pages["A"] = "includes/contentA.php";
pages["B"] = "includes/contentB.php";
pages["C"] = "includes/contentC.php";
for (var key in pages) {
var URL = pages[key];
$.get(URL, function(html) {
contentArray[key] = html;
});
}
However, this doesn't work. contentArray only has one property containing html data, rather than three. I'm knew to jQuery, particularly the AJAX stuff, so both explanations and solutions (similar or different-method-same-result) are welome.
By the way, I'm aware that one larger AJAX request is preferable to multiple small ones, but I'm trying to retain compatibility for users without JS enabled, and the current php includes are convenient. Any suggestions as how I might satisfy both these requirements are also very welcome.
Thanks.
The callback function for an AJAX request doesn't run until the request returns. In your case each callback function will use key as it exists in the current context, and since there's no key variable in it's local scope it will use the nearest it can find, the key in your for loop.
The problem is by the time the AJAX requests return, the for loop has been fully iterated over and key is equal to the last key in the array. Thus each of the callback functions will receive the same key, overwriting the previous value in your contentArray.
If you're using jQuery 1.5.1 or above a quick and dirty solution (one that doesn't involve changing the current structure of your PHP files) might be to try the following:
for (var key in pages) {
var URL = pages[key];
$.ajax({
url: URL,
xhrFields: {
'customData': key
},
success: function(html, statusText, jqXHR) {
contentArray[jqXHR.customData] = html;
}
});
}
I haven't tested that but according to the documentation page it should work. All you're doing is using the request object created by jQuery to pass your variable along to the callback function.
Hope that helps

MVC: Set value in autocomplete on Edit

In our MVC application we use jQuery autocomplete control on several pages. This works fine on Create, but I can't make it work on Edit.
Effectively, I don't know how to make the autocomplete controls preload the data from model and still behave as an autocomplete in case the user wants to change the value.
Also how can I make sure that the value is displayed in the same format that is used in Create calls?
All our autocomplete controls have corresponding controllers and all parse Json results.
Let's Try this! Alright Do this:
Suppose you had a list of countries you needed to filter
Auto Complete knows how to some default things by default but suppose you really wanted CountryName and also you know every keypress does an ajax call to the URL you specify.
Create an action method like so:
public ActionResult LookupCountry(string q, int limit)
{
var list = GetListOfCountries(q, 0, limit);
var data = from s in list select new {s.CountryName};
return Json(data);
}
Here is the Jquery:
$(document).ready( function() {
$('#txtCountryName').autocomplete('<%=Url.Action("LookupCountry", "MyController") %>', {
dataType: 'json',
parse: function(data) {
var rows = new Array();
for(var i=0; i<data.length; i++){
rows[i] = { data:data[i], value:data[i].CountryName, result:data[i].CountryName};
}
return rows;
},
formatItem: function(row, i, n) {
return row.CountryName;
},
width: 300,
mustMatch: true,
});
});
Here is the Html
<html><head></head><body>#Html.TextBox("txtCountryName",Model.CountryName)</body></html>
Basically, The magic is in the call to LookUpCountry
The GetCountriesList(string query, int startindex, int limit)
Returns MyCountries.Where(c => c.CountryName.SubString(startindex, limit).Contains(query)).ToList();
So you are making your own trimming function because JQuery has no idea what CountryName is or how to trim it. How ever if it was a javascript object I am not quite sure but do
var jsonString = #Html.GetListOfCountries() //Or Model.Countries.ToJSONString()
var json = JSON.stringify(jsonString); //also JSON.Parse(jsonString) if stringify won't work
which would return the necessary countries as a Html Helper Extension method. And perhaps as a list of javascript objects it would be smart enough to handle it that way in it's native language. However the first approach works for me.

Resources