Develop Reference

how to update model field data when Javascript event occurs

I'm doing on a Django Project.
There is a post model, and the post has 'likes' field. When a user clicks the Like button on a post, I want to increase the number of the Likes of the post.
I want to solve the problem only with Django without REST framework(DRF)
what can I do?

You have to make an endpoint that javascript can be directed to. Create a view that will do the process:
def add_like(request, post_id):
# here you can create process that will find Post object by provided id
return JSONResponse(...) # however not needed, you can create some response with status 201
Then obviously url pointing to that view:
urlpatterns = [
path('add_like/<int:post_id>', my_app.add_like),
]
Then anytime you will post to i.e. /add_like/1, it will activate the process in add_like view. You can put there more variables (like user who is liking).

Mvc use string on multiple page

I'm making a patient web app. When user add new patient, I want to keep this patient information(name, surname, phone etc.) I created a static class for patient info values. I set datas on this class. How can I get this info on another views?
This is info class: https://imgur.com/a/LnncS3S
I tried access on view like that:
#{Dentilog.Models.patientinfo.patient_id}
I getting data on views like that (I already set data values on form input)
https://imgur.com/a/h4JprXO
and in controller: https://imgur.com/a/225dBe6
I dont have any problem for getting data. How can use that data on another page?

Redux - Remove object from store on http response error

Consider the following flow:
I have a page with a list of "products" and a modal to create a single "product". I open the modal, fill the form and submit the form.
At this point, I dispatch an action CREATING_PRODUCT, add the product to the store and send the http request to the server.
I close the modal and display the list of results with the new product.
Let's suppose I receive an error response from the server.
Desired behavior:
I would like to display an error, remove the project from the list, re-open the modal and display the form already filled.
Question
How can I find that project and remove it the list? I don't have an id (or a combination of unique properties) to find that project in the store. I don't see a clean way to link a request/response to that "product" object in the store.
Possible solution
The client adds a "requestId" into the project before adding it to the store. On response error, I dispatch a generic "CREATE_ERROR" and I remove the project with that requestId from the store.
Extra
Same problem with edit and delete. For example during a delete should I keep a reference to the deleted project with the requestId in the store, until the http request is successful?
I bet it is a problem with a common solution, but I can't find examples.
Thanks!

In general, your Redux store should be modeled somewhat like a relational database, in that every time you have a list of data models, each element of the list should have its own identifier. This helps a lot when dealing with more complex data schemes.
You should probably store your projects as an object, something like:
{
// ...other store properties
projects: {
"_0": { // ... project properties }
"_1": { // ... project properties }
// ...more projects...
},
}
This way, whenever you need to mess with an existing project, you can just reference its id and use projects[id] to access that project. This would also solve the edit and delete cases, as you could just pass the IDs around as handles.
I like this short piece on why your Redux store should be mostly flat and why data should always have identifiers very much. It also talks about using selectors to "hide" your IDs away, which may or may not be useful for you.
In your case, as you are getting IDs from a server, you could have an ID prefix which indicates unsaved values. So your projects object would become something like:
projects: {
"_0": { // ... }
"_1": { // ... }
"UNSAVED_2": { // ... }
}
This way, you could easily identify unsaved values and handle them when an error occurs, still get the benefits of generating temp IDs on the client-side in order to revert changes on error, and also warn your user if they try to leave your app while their data still hasn't been synchronized - just check if there are any "UNSAVED" IDs :)
When you get a response from the server, you could change the "UNSAVED_suffix" ID to an actual ID.

Backbone.model.save(): POST(create) / PUT(update) logic doesn't match application logic - how to avoid PUT in certain situations?

I'm creating an Web-Application (Frontend and Backend, so both are under my control) using Backbone and Pyramid, being connected via a RESTful API.
During development I encountered a problem several times by now, where Backbone PUTs (=updates) a new model, while it actually should POST (=create) it.
Backbone decides whether to POST or UPDATE a model depending of the presence of an ID-field (if no ID present in the current model: -> POST/create | if so: PUT/update).
However I encountered several situations by now, where this behaviour doesn't match my application logic.
Let's say our main model (and its objects being persistently saved in a relational database in the backend) is called Foo, having fields like id, field_1, field_2.
Example #1: Creating a template or preview of Foo: Before creating (=POSTing) an object of Foo, I can create and show a preview to the user and/or save it as a template.
While doing so, the backend (in case of the preview: temporarily) adds the object to the database and returns the full model - including an ID in its HTTP response - back to Backbone.
Template- and Preview-objects of Foo are (temporarily) saved into the same table, as final objects (column type indicates its type (0 = final/live, 1 = preview, 2 = template)).
When now - after previewing / saving as template - trying to actually CREATE an object of Foo, the Backbone model already has the ID field set and actually PUTs and updates the template or not-anymore-existing preview, instead of POSTing and therewith creating a new Foo inside the database (as intended).
=> solution #1: calling POST /json/preview does not return the ID field, so Backbone doesn't get confused.
=> solution #2: overriding parse() of Foo in Backbone-model to kick out ID field from response
.=> kinda works
Example #2: Having a Periodic model, which refers to a Foo-template. Intention of a Periodic is to offer the user the possibility of semi-automatically creating a new Foo object based on a Foo-template every X months.
Now there is a call GET /json/periodics, which returns all Periodic-objects with its nested Foo-objects (Foo-templates), including their IDs, e.g. [{'interval': 12, template_id: 42, template: { 'id': 42, field_1: 'foo', field_2: 'bar', .. } , { .. } , .. ].
On the frontend the user now can periodically confirm (or skip) creating a new Foo-object, by issuing: periodics[X].template.save() which however again PUTs and therewith updates the Foo-model, instead of POSTing and creating a new one (as intended).
Here again (as in example 1), I could strip out the ID field of Foo - either in the backend or frontend.
However there are situations, where I need the id-field of templates, e.g. when actually editing them, so here I'd need two calls (GET /json/templates_WITHOUT_FOO-IDs and GET /json/templates_WITH_FOO-IDs). which also sounds far from right.
Question is: What's the right (and consistent) way of avoiding Backbone falsely assuming a model should be PUT instead of POSTed in certain situations / views?

Backbone's save and fetch methods just make calls to the Backbone.sync
method, which in turn is just a wrapper for an ajax call. you can pass
in ajax parameters using the save function without having to actually
extend it. basically ends up being something like this:
model.save({attributes you want to save}, {type:'POST', url: 'apiurl/model/:id/played'});
You would have to do this every time though so it is probably better practice to extend Backbone.sync for your model.
The Backbone website has a bit of information about what I'm talking about as far as the Backbone sync and save taking ajax options. There are also a few examples I've seen on extending sync but I can't seem to track them down at the moment.

Authentication with devise rails using backbone

I am new to backbone.js. I am developing a rails application using "backbone-on-rails" gem. I have included 3 models and rendering views uisng backbone. It worked fine. Now i want to add authentication to my app using devise, after the user has signed in only my app needs to be rendered otherwise i need to redirect to login page.
I have added devise gem for it.
Can someone please help me on how can i check whether user has signed in or not, if user hasn't logged in need to redirect to devise sign_in page using backbone?
Thanks in Advance

Backbone's a frontend-only framework, so it doesn't have a concept of authentication. All the source code is sent to the web browser, and all the network connections are plain to see, so a malicious user can trick your app into thinking it's logged in, even if it isn't. So you'll still need to check access permissions on the server.
What you can do, though, is have your Backbone app detect whether it thinks it's logged in, and change its display based on that. For instance, you could use Devise's user_signed_in? helper to add a data attribute on your body tag, and hook into that. Something like this in your app/views/layouts/application.html.erb:
<body data-user-signed-in="<%= user_signed_in? ? "true" : "false" %>">
And then, maybe your Backbone router is going to look something like this:
myApp.Routers.Router = Backbone.Router.extend({
routes: {"": "showFrontPage"},
isSignedIn: function() {
return $('body').data('user-signed-in') === "true";
},
showFrontPage: function() {
var view;
if (this.isSignedIn()) {
view = new myApp.Views.MainAppView();
} else {
view = new myApp.Views.SignInView();
}
view.render();
}
});
Alternatively, you could look directly for a session cookie. That seems a bit more brittle to me, though; if the name of your application changes, or Rails changes how it names its cookies, your app's going to break. But in that case, your isSignedIn() function is going to look more like this:
isSignedIn: function() {
return document.cookie.indexOf("_Railsappname_session") > -1;
}
If you want to check your user at various points of your app, you could easily write a controller method that returns the result of user_signed_in? as a JSON object. But it's better not to rely on this; rather than calling /user/is_signed_in and then /posts/create, far better to do one call to /posts/create and have that return a 401 Unauthorized if the user's not logged in.
As for logging in itself, you can adapt Devise to work via JS so you can login via AJAX, but it's not as straightforward as you might hope. There's a tutorial here.

I needed to implement a backbone login in rails with devise. Note that for my purposes I did not need user registration as well, since I wanted to have just one admin user, created manually in the terminal by me.
Basically as long as you make an AJAX post request to the right devise route, devise will handle the login for you (assuming of course you went through the devise setup process correctly).
In Backbone you can make this post request using a new model save.
This tutorial helped me set up my Backbone model and view (FYI: the tutorial also goes over what you need to do in order to add registration functionality).
The tutorial had some more advance backbone setup (for example it uses backbone.marionette and backbone.modelbinder) which although very useful, I did not want to get into. Below is my simplified version of the tutorial to the bare core of what you need.
Create a model with the urlRoot that matches your devise login route. For most people that go with the standard User model, the urlRoot route below should work. Note my code is written in coffeescript
class MyCoolBackboneApp.Models.UserSession extends Backbone.Model
urlRoot: '/users/sign_in.json'
defaults:
email: ""
password: ""
toJSON: ->
{ user: _.clone(#attributes) }
Note that devise expects the params to be wrapped inside 'user' which is why we had to overwrite the toJSON method
Then in your view, all you need to do is save the model together with the login credentials. Of course every person might have a different success and failure callback, but here is a very basic implementation:
events:
'submit form': 'login'
initialize: =>
#model = new MyCoolBackboneApp.Models.UserSession()
render: =>
$(#el).html( #template() )
#
credentials: ->
{
email: #$('#email').val(),
password: #$('#password').val(),
remember_me: 1
}
login: (event)->
event.preventDefault()
#model.save(#credentials(),
success: (userSession, response) =>
window.location.href = "/"
error: (userSession, response) =>
message = $.parseJSON(response.responseText).error
alert(message)
)
You should also read this tutorial about how to set up devise ajax authentication.
After you complete the above tutorial, you should be able to save your UserSession model with the right credentials (as I do in the view) and login successfully (assuming you have a saved existing user in your Database). You'll know you've logged in successfully when you get redirected to your success callback.
Then in the controllers in the rest of your app, you should be able to use the devise helpers: user_signed_in? or current_user etc etc.
(If you are logged in but get an undefined method error for these helpers, try to add: include Devise::Controllers::Helpers to your controllers).
Finally Alex P's response can then walk you through how to use the user_signed_in? boolean in your Backbone views.