AngularJS binding between variables - javascript

I've got a list of users which I retrieve from my service. When I select any user I can see and edit info (email, roles, etc). The problem is that I don't want these changes to affect user's data in the list, I want to update data only after saving (clicking a button).
Now I'm using two variables:
$scope.selected - currently selected user
$scope.editable - variable for storing the data I'm editing
And I exchange data like this:
$scope.initEditable = function ()
{
$scope.editable = {};
$.extend($scope.editable, $scope.selected);
}
Looks like a terrible solution. What is the proper way to do it?

Actually, this is the Angular-way of approaching this problem, you are on the right track. In scenarios like yours one would typically:
Copy an item upon selection (edit start) - this is what you do with editable
Have 2-way data binding changing a copy (or an original element)
Upon edit completion we can propagate changes from a copy to the original
The nice things about this pattern is that we can easily:
Offer the 'cancel' functionality where users can revert their changes
Be able to compare a copy and the original and drive parts of the UI based on this comparison (for example, we could disable a 'Save' button if there were no changes)
So, I don't think at all that this approach is terrible. The only suggestion I could have is to use angular's angular.copy method instead of $.extend.

Related

How to pass an array from javascript to php

So i've been asked to remake some registration forms. The way its supposed to work is, that an interpreter chooses X amount of languages in the first select box. Then based on the selections of languages, the user must specify from which languages they can translate from/to.
I want to store this data in a key/value array, with the key being "LanguageFrom" and Value being another array, of "LanguagesTo". This is how i have solved this:
function btnTest() {
var fromArray = $('.freelancerLanguagesFrom').map(function() {
return $(this).val();
}).get();
var toArray = $('.freelancerLanguagesTo').map(function() {
return $(this).val();
}).get();
var tempArray = {};
tempArray[fromArray] = toArray;
}
This method is being called with an "onclick" function in the html part. The user should specify which languages he can translate to for each of the chosen languages in the first box,
I am aware that this probably isn't the ideal approach, but im still an inexperienced developer, and i'd love to hear your take on another approach.
Now comes my problem:
1) How do i make it so the array wont overwrite the existing array with each button click, and instead just add to the array?
2) How do i process this array on the server side (php), so that i can store the values in my database?
3) Is it possible to skip the flow where the user has to press the save(gem) button after each language he has chosen?
edit: Question 1 and 3 are now solved, my only problem is accessing the array i made in js, on the php side
1) tempArray exists only in the scope of the btnTest() function. Declare it outside (in the global scope), initialize it as {} and don't reset it every time you click the button. The way you get the fromArray variable may require some tweaking depending on whether the "from" list can accept a multiple selection or not.
2) Ajax may help. Create a php endpoint to receive the request and call it using ajax. You can work on the array using JSON. Send your data using JSON.stringify(tempArray) and read it using json_decode() in your php script, or simply set the request headers as "application/json" to have it done automatically for you.
3) I personally wouldn't automate this process. Let's say I have 4 languages, Italian, English, French and Chinese.
I have selected a desirable state of languages I can handle:
Italian -> English, French
But I also know how to translate French in Italian so I click, in the from list, French, and I get
French -> English
Which is an undesirable state, for me, because I don't know how to do that. Especially if I were to select many languages, I'd get, inbetween 2 states I want to save, an indefinite amount of states I don't want to save.
If you still want to do so, you need to move the even listener from the button to the list(s), with the onchange event.
I'd also suggest you do your event binding trough jQuery, if you aren't already.
Hope this helped.

Clone sapUi5 json model and stop binding

I have seen a similar question, but in my case it doesn't work.
I have a JSON model, called data, which corresponds to a SAPUi5 form with comboboxes. I want to copy the state of the model the first time I open my application and keep it like that. After that I want to use it to reset my form and bring the comboboxes back to their default values.
When I first start my application:
this.getView().setModel(new JSONModel(data)); //create the original model
//copy the original model (copyModel is global variable
copyModel = $.extend({}, data);
Until here everything is fine. The two models are exactly the same. After that I have a button and a reset Function:
resetP: function(){
this.getView().setModel(new JSONModel(copyModel));
console.log(copyModel);
}
The first time I select something in the comboboxes and click the reset button and run the reset function, the copymodel is the right one. Same with the original data model. When I change again the selected value of the combobx, the copyModel, starts taking the selected value. Somehow it's overwritten. I don't know what I am doing wrong. Are there any suggestions? I have also tried to use JSON.strignify instead of extend.
JSON models be default have two way binding. So when you are triggering events like selectionChange on the ComboBox, because of two way binding, the set data to the model keeps getting updated. Also Javascript has objects by reference, so it is the original copyModel object that gets updated.
You can prevent this by setting a copy of the copyModel to the JSON model.
Another thing I would like to mention is that do not keep setting the model again and again.
You can just update the data that is set to the model and update the model.
This can be done in 2 ways.
a.
resetP: function(){
this.getView().getModel().setData(copyModel);
console.log(copyModel);
}
b. You could also update the required property and do a
this.getView().getModel().updateBindings();
We use jQuery.extend(true, {}, object_to_copy); in this way to create a "deep copy" from the object we want an independed copy from.

KnockoutJS: Stop a particular property from setting dirty flag

With some help from StackOverflow community I was able to get my dirty flag implementation to work, based on this example: http://www.knockmeout.net/2011/05/creating-smart-dirty-flag-in-knockoutjs.html
It does exactly what I want, except for a single use case that I don't know how to solve.
Basically I have a select menu that gets automatically populated from the database. This select menu also has an option to make an Ajax call to my back end and have the list of options refreshed, database updated and return the result. This is where things get hairy for me.
First method works fine, however, it has to re-index and re-apply my entire viewModel and takes about 2-3 seconds, running on a local machine with 16gigs of ram and SSD.
jsondata.component.available_tags = result.available_tags;
ko.mapping.fromJS(jsondata, viewModel);
Second method also works, and pretty much instantaneous, however, it sets of isDirty() flag, which I would like to avoid, because this data is already coming from the database and I wont need to save it. I can not use isDirty.reset() method either, because if isDirty was set by something else before I clicked an menu option to update available_tags, it will reset that too. Which I would also like to avoid.
viewModel().component.available_tags(result.available_tags);
My question is: With the first method, can I force UI refresh with ko.mapping.fromJS() on a particular element and not entire dataset? Or, with a second method, can I avoid setting isDirty flag set when available_tags are updated? The twist is that I still need to keep available_tags as an observable, so the select menu is automatically generate/updated.
UPDATE: I was able to update mapping for that one single element with
ko.mapping.fromJS(result.available_tags, {}, viewModel().component.available_tags);
but that immediately set off isDirty flag... Argh
In addition to Tomalak's suggestions, which I totally agree with, maybe the toJSON method can help you out in similar cases where you don't want to split the model. If your dirty flag implementation uses ko.toJSON as a hash function, as Ryan Niemeyer's does, you can give your model (on which the dirty flag is active) a toJSON method, where you do something like this:
function MyObjectConstructor() {
this.someProperty = ko.observable();
this.somePropertyNotUsedInDirtyFlag = ko.observable();
}
MyObjectConstructor.prototype.toJSON = function () {
var result = ko.toJS(this);
delete result.somePropertyNotUsedInDirtyFlag;
return result;
};
Please be aware that this is also used to serialize the object in some other occassions, such as ajax calls. It's generally a handy function for removing computeds and such from your objects before using them in a different context.

Checking for any dirty Backbone model data within collection

I have a requirement to "nag" a user about unsaved changes when they switch between different Backbone collection models (by clicking on a table row). I've googled for "check backbone model dirty data" (for instance) and not found anything definitive.
I accomplished this using underscore's "some" and isEqual functionality, in a manner such as the following, "some()" being sufficient to determine if there are any un-saved changes (as opposed to what those precise changes might be), in particular because the model attribute is actually an array of objects.
var anyDirty = _.some(myCollection.models, function(model) {
return !_.isEqual(model.get('nodes'), model.previousAttributes()['nodes]);
});
I am new to Backbone and am wondering if this is an accepted sort of approach for adhoc checking for dirty model data. Or, does Backbone provide some sort of built in functionality for this purpose, that my initial attempts at googling did not reveal?
I have another attribute I need to monitor in addition to 'nodes', so I'm switching to using changedAttributes(): http://backbonejs.org/#Model-changedAttributes:
var anyDirty = _.some(myCollection.models, function(model) {
return model.changedAttributes();
});
What may make this an imperfect solution is that it seems like it will return an object of changedAttributes even if the attribute got changed back to it's original value. So it almost seems that what I need in the long run is to take a snapshot of the original data and compare against that. Still though, using model.changedAttributes() is a more concise alternative to what I first posted.

With Backbone.js, how to Bind to an array's changes w/o needing to manually trigger?

I'm creating an invitation dialog that allows users to enter emails. Currently in the model I am creating an array to hold the emails:
initialize : function() {
this.model.set({
invite_email_array : new Array()
});
}
And then I'm adding/removing items in the view like so:
this.model.get('invite_email_array').push('email#domain.com');
Then problem is the binder is not being triggered when I either add or remove an email from the model. Here is my binder:
binder : function() {
model.on("change:invite_email_array", onInviteEmailArrayChange() )
}
The only way I was able to get the binding to trigger was to trigger it manually when I make updates.. an ugly hack
this.model.trigger("change:invite_email_array");
Any suggestions on a better way to maintain a list of emails and then be able to bind to the object on add/removes?
Thanks
In the example you give, you're bypassing set by altering the array directly. In order to trigger the change, you would need to set the altered array after pushing the new e-mail. Something to the effect of:
var arr = _.clone(this.model.get('invite_email_array'));
arr.push('email#domain.com');
this.model.set({ invite_email_array: arr });
As soon as you've introduced an array, however, it may be worth considering whether the view's design is really reflecting its intent. Collections (or arrays) of anything often signal that it's time to consider simplifying models or views. Even though a single e-mail seems too trivial assign to its own view/model, it may make sense to track an array of e-mails as a collection of "invitation" views and watch for changes accordingly.

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