I have this webshop, and on one page you see
products;
with a submitting form for a booking;
your order with its bookings;
with a removing link for a booking;
and an updating form for a booking.
Both the order.bookings and the products make potentially long lists on a html page.
The whole booking works by only a booking_controller.
What the booking_controller does:
Takings in the (new) params of a single booking or the destroy action.
Saves the new order.
Redirects to the store.
Works fine, just using ruby and html.erb.
Only problem, and this really needs to change, is that obviously after each redirect the browser goes to the top of the page. The browser isn't focussed. Or better to say, the browser should remain, but doesn't.
I get that your doing all these things on the server-side, so a page reload, or better to say, data-refresh, is necessary. What I don't want is building this whole thing again on the client-side (JS).
Can't I simply say something like: after data refresh redirect to exact same spot on page. Ignoring all the difficulties an asynchronous request would give, or am I exaggerating and is a little JS easy?
With Rails, using ajax is very easy however if you're not familiar with ajax at all it can be a bit daunting at first. Luckily there are many tutorials on the subject. Basically, add the remote: true option to your form_for statement and rails will automatically understand you want it to make a 'POST' request in JS format. It's important to realize that the incoming HTTP request is in JS format because you'll then need to specify handling that event in the controller. Such as:
def create
#Do whatever saving and processing you need here
respond_to do |format|
format.html { redirect_to some_path_here }
format.js { } #By not adding anything in the brackets here, you're telling rails to fetch a js view file that follows standard rails convention and so it should be named 'create.js.erb'
end
Then in your controller's views folder create the view file create.js.erb. In that file you'll want to refresh whatever part of the page needs updating which usually involves hiding the old div that was there and appending a partial in its place. I usually leave an empty div with an ID on the page (in this case your new_whatever_page.html.erb that I then call in the js.erb file to append a partial to:
In your create.js.erb add:
$("#the-id-of-the-div-in-your-new-view-page").html("<%= escape_javascript(render 'order_table') %> #This basically says, find the div on the current page with a matching id and then append the partial named _order_table.html.erb to it.
Now just make a partial named
_order_table.html.erb
in the same views folder and put whatever content you want to insert or update.
When a rails form fails on the the front end, how is the javascript handled? e.g. a numericality error fails or a required: true option is not fulfilled.
I would like to add a callback function to this. Is there any way to execute some javascript on the failure?
There is no javascript involved on the rendering of the errors on a rails form. The way the errors are displayed are determined by a function called field_error_proc, specifically ActionView::Base.field_error_proc. You can check Ryan Bates' railcast about it
If you are submitting your form via AJAX, you can attach a listener for the ajax:success event. Otherwise the only (ugly) way I can imagine is to do something like:
$(document).on('app:form-has-errors', function() { //do what you have to do} and on the view
<script>$(document).trigger('app:form-has-errors');</script> if the object in the form has errors (#your_object.errors.any?).
I don't think it is possible in another way since the submit and re-render on errors are complete http requests that will clear any events you might bind to the document.
Rails built in validation doesn't operate on the front end (client-side), it is done on the server.
If you want to do javascript validation you will need to find a gem for this or use a jQuery library, or write the validation code yourself.
The normal way form validation is done when using vanilla Rails is like this
The invalid form content is submitted to the controller
The controller uses the content to make the ActiveRecord object
The controller tries to save the object to the Database, kicking off a set of steps that starts with checking the object's validity
The model's validators say it's not valid and "decorate" the object with error messages specifying in which ways it is not valid.
The controller sees that the save failed and renders the view that had the original form in it, providing that view with the object, now with error messages.
The view when it renders the form checks the object for error messages, if it sees any it helpfully displays them to the user. It also populates the fields with the data that the user had previously entered that it gets from the object.
what is the difference between Html.BeginForm() and Ajax.Beginform() in MVC3. I just want to know the scenarios where I can use Html.BeginForm() and where I can use Ajax.Beginform().
Ajax
Won't redirect the form even you do a RedirectAction().
Will perform save , update and any modification operations asynchronously.
Validate the Form using FormMethods - OnSubmit. So you are abort the Post
This creates a form that submits its values using an asynchronous ajax request. This allows a portion of the page to be update without requiring that the entire page be refreshed.
Html
Will redirect the form.
Will perform operations both Synchronously and Asynchronously (With some extra code and care).
Html.BeginForm will always use RouteTable to detrmine the action attribute value.
This will create a form on the page that submits its values to the server as a synchronous HTTP request, refreshing the entire page in the process.
Html.BeginForm() will create a form on the page that submits its values to the server as a synchronous HTTP request, refreshing the entire page in the process.
Ajax.BeginForm() creates a form that submits its values using an asynchronous ajax request. This allows a portion of the page to be update without requiring that the entire page be refreshed.
Html.BeginForm() will use simple posting on page, it means your page will be refreshed when you post your form.
when Ajax.BeginForm() will use ajax posting on page, it means your page will not be refreshed when you post your form.
#Html.BeginForm is used to post the data by full page refresh whereas #Ajax.BeginForm performs Post back function and allows some portion of Html to be reloaded rather than overall page refresh.
In an effort to have everything translateable in our website ( including the error messages for the validations ), we switched almost all of our forms to remote forms. While this helps with the ability to translate error messages, we have encountered other problems, like:
if the user clicks on the submit button multiple times, the action gets called multiple times. If we have a remote form for creating a new record in the database, and assuming that the user's data is valid, each click will add a new object ( with the exact same contents ). Is there any way of making sure that such things cannot happen?
Is there somewhere I could read about remote forms best practices? How could I handle the multiple clicks problem? Is switching all the forms to remote forms a very big mistake?
There is a rails 3 option called :disable_with. Put this on input elements to disable and re-label them while a remote form is being submitted. It adds a data-disable-with tag to those inputs and rails.js can select and bind this functionality.
submit_tag "Complete sale", :disable_with => "Please wait..."
More info can be found here
Easy, and you can achieve that in many ways depending your preferences:
Post the form manually simply using an ajax request and while you wait for the response disable/hide (or whatever you need) the form to ensure the user can't keep doing posts as crazy. Once you get the response from the server, again you can allow the user to post again (cleaning the form first), or show something else or redirect it to another page or again whatever you need.
Use link_to :remote=>true to submit the form and add a callback function to handle the response and also to disable/hide (or whatever you need) the form when it's submitted
Add a js listener to the form to detect when it's submitted and then disable/hide/whatever the form
As you see, there are lots of different ways to achieve what you need.
EDIT: If you need info about binding or handling a form submit from js here you'll find very easy and interesting examples that may help you to do what I suggested you! jQuery Submit
I have remote forms extensively myself, and in most cases I would avoid them. But sometimes your layout or UX demands for on-the-fly drop-down forms, without reloading or refreshing the complete page.
So, let me tackle this in steps.
1. Preventing Normal form double-post
Even with a normal form, a user could double-click your button, or click multiple times, if the user does not get a clear indication that the click has been registered and the action has started.
There are a lot of ways (e.g. javascript) to make this visible, but the easiest in rails is this:
= f.button :submit, :disable_with => "Please wait..."
This will disable the button after the first click, clearly indicating the click has been registered and the action has started.
2. Handling the remote form
For a remote form it is not that much different, but the difference most likely is: what happens afterward ?
With a remote form you have a few options:
In case of error: you update the form with the errors.
you leave the form open, allowing users to keep on entering the data (I think this is your case?)
you redirect the users to some place.
Let me handle those cases. Please understand that those three cases are completely standard when doing a normal form. But not when doing a remote call.
2.1 In case of error
For a remote form to update correctly, you have to do a bit more magic. Not a lot, but a bit.
When using haml, you would have a view called edit.js.haml which would look something like
:plain
$('#your-form-id').replaceWith('#{j render(:partial => '_form') }');
What this does: replace the complete haml with only the form. You will have to structure your views accordingly, to make this work. That is not hard, but just necessary.
2.2 Clearing the form
You have two options:
* re-render the form completely, as with the errors. Only make sure you render the form from a new element, not the just posted one!!
* just send the following javascript instead:
$('#your-form-id').reset();
This will blank the form, and normally, that would effectively render any following clicking useless (some client validation could block posting until some fields are filled in).
2.3 Redirecting
Since you are using a remote form, you can't just redirect. This has to happen client-side, so that is a tad more complicated.
Using haml again this would be something like
:plain
document.location.href = '#{#redirect_uri}';
Conclusion
To prevent double (triple, quadruple, more) posts using remote forms you will have to
disable the button after first click (use :disable_with)
clear the form after succesful submission (reset the form or render with a new element)
Hope this helps.
The simplest solution would be to generate a token for each form. Then your create action could make sure it hasn't been used yet and determine whether the record should be created.
Here's how I would go about writing this feature. Note that I haven't actually tested this, but the concept should work.
1.
Inside the new action create a hash to identify the form request.
def new
#product = Product.new
#form_token = session["form_token"] = SecureRandom.hex(15)
end
2.
Add a hidden field to the form that stores the form token. This will be captured in the create action to make sure the form hasn't been submitted before.
<%= hidden_field_tag :form_token, #form_token %>
3.
In the create action you can make sure the form token matches between the session and params variables. This will give you a chance to see if this is the first or second submission.
def create
# delete the form token if it matches
if session[:form_token] == params[:form_token]
session[:form_token] = nil
else
# if it doesn't match then check if a record was created recently
product = Product.where('created_at > ?', 3.minutes.ago).where(title: params[:product][:title]).last
# if the product exists then show it
# or just return because it is a remote form
redirect_to product and return if product.present?
end
# normal create action here ...
end
Update: What I have described above has a name, it is called a Synchronizer (or Déjà vu) Token. As described in this article, is a proper method to prevent a double submit.
This strategy addresses the problem of duplicate form submissions. A synchronizer token is set in a user's session and included with each form returned to the client. When that form is submitted, the synchronizer token in the form is compared to the synchronizer token in the session. The tokens should match the first time the form is submitted. If the tokens do not match, then the form submission may be disallowed and an error returned to the user. Token mismatch may occur when the user submits a form, then clicks the Back button in the browser and attempts to resubmit the same form.
On the other hand, if the two token values match, then we are confident that the flow of control is exactly as expected. At this point, the token value in the session is modified to a new value and the form submission is accepted.
I hate to say it, but it sounds like you've come up with a cure that's worse than the disease.
Why not use i18n for translations? That certainly would be the 'Rails way'...
If you must continue down this route, you are going to have to start using Javascript. Remote forms are usually for small 'AJAXy things' like votes or comments. Creating whole objects without leaving the page is useful for when people might want to create lots of them in a row (the exact problem you're trying to solve).
As soon as you start using AJAX, you have to deal with the fact that you'll have to get into doing some JS. It's client-side stuff and therefore not Rail's speciality.
If you feel that you've gone so far down this road that you can't turn back, I would suggest that the AJAX response should at least reset the form. This would then stop people creating the same thing more than once by mistake.
From a UI/UX point of view, it should also bring up a flash message letting users know that they successfully created the object.
So in summary - if you can afford the time, git reset and start using i18n, if you can't, make the ajax callback reset the form and set a flash message.
Edit: it just occurred to me that you could even get the AJAX to redirect the page for you (but you'd have to handle the flash messages yourself). However, using a remote form that then redirects via javascript is FUGLY...
I've had similar issues with using a popup on mouseover, and not wanting to queue several requests. To get more control, you might find it easier to use javascript/coffeescript directly instead of UJS (as I did).
The way I resolved it was assigning the Ajax call to a variable and checking if the variable was assigned. In my situation, I'd abort the ajax call, but you would probably want to return from the function and set the variable to null once the ajax call is completed successfully.
This coffeescript example is from my popup which uses a "GET", but in theory it should be the same for a "POST" or "PUT".
e.g.
jQuery ->
ajaxCall = null
$("#popupContent").html " "
$("#popup").live "mouseover", ->
if ajaxCall
return
ajaxCall = $.ajax(
type: "GET"
url: "/whatever_url"
beforeSend: ->
$("#popupContent").prepend "<p class=\"loading-text\">Loading..please wait...</p>"
success: (data) ->
$("#popupContent").empty().append(data)
complete: ->
$"(.loading-text").remove()
ajaxCall = null
)
I've left out my mouseout, and timer handling for brevity.
You can try something like that for ajax requests.
Set block variable true for ajax requests
before_filter :xhr_blocker
def xhr_blocker
if request.xhr?
if session[:xhr_blocker]
respond_to do |format|
format.json, status: :unprocessable_entity
end
else
session[:xhr_blocker] = true
end
end
end
Clear xhr_blocker variable with an after filter method
after_filter :clear_xhr_blocker
def clear_xhr_blocker
session[:xhr_blocker] = nil
end
I would bind to ajax:complete, (or ajax:success and ajax:error) to redirect or update the DOM to remove/change the form as necessary when the request is complete.
Here is my use case
I have a search model with two actions search_set and search_show.
1 - A user loads the home page which contains a search_form, rendered
via a partial (search_form).
2 - User does a search, and the request goes to search_set, the search
is saved and a redirect happens to search_show page which again
renders the search_form with the saved search preferences. This search
form is different than the one if step1, because it's a remote form
being submitted to the same action (search set)
3 - Now the user does another search, and the search form is submitted
via ajax to the search_set action. The search is saved and executed
and now I need to present the result via rjs templates (corresponding
to search_show). I am told that if the request is xhr then I can't
redirect to the search_show action? Is that right? If yes, how do I
handle this?
Here is my controller class
http://pastie.org/993460
Thanks
That's right. Either make the request non-XHR and redirect as normal, or you could try rendering the URL you want to redirect to as text or part of a JSON object which your AJAX request then uses to call document.location.href = [whatever] (but this seems hacky).
Right now what's happening is your XHR request is returning the result of the redirect, and not actually redirecting the page that made the XHR request.