I have an app that uses Backbone on the client side and Rails on the back end.
My Backbone code calls an underscore template in this manner:
var todo = Backbone.View.extend({
.
template : _.template( $('#todo_rows').html() ),
.
}
However, there's only one page on the site which would need to call this template, and the Backbone js loads on every page. That means that there will be a JS error on the other pages which don't have the "#todo_rows" underscore template defined.
One solution would be to create a blank "#todo_rows" template section for all the other pages, but this strikes me as a major hack and not the best way to deal with this problem.
What is the best way to disable the code to call a template in Backbone? It needs to be disabled if you are not on the home page OR if you are not logged in.
Underscore's template is happy with receiving an empty string as argument. As $('#todo_rows').html() returns null if the #todo_rows element does not exist, you can easily avoid the JS error by using the or-operator idiom:
template : _.template( $('#todo_rows').html() || '' ),
which means "use an empty string as dummy template if the real one is not available".
Another, Rails-specific workaround for this problem (and a neat approach in general) is to add the ejs gem to your project's Gemfile, which allows you to put each template in a separate .jst.ejs file in app/assets and have the Asset Pipleline compile it to a JST object that can be accessed by your view to get the template content:
templates/todo_rows.jst.ejs
<% // Your template (content of former "#todo_rows") here %>
todo_rows_view.js
//= require templates/todo_rows
var todo = Backbone.View.extend({
template : _.template(JST['templates/todo_rows']),
// ...
}
This avoids the roundtrip to the DOM and makes it possible to nicely organize the templates into multiple files, but has the drawback that the template string will be sent as part of the JavaScript code for every page including it.
Related
I've partial templates that are used by the show, edit and create form.
In the show-form I don't want them editable, it can be confusing for the user.
Is there a simple solution for this otherwise I need a different template for the show-form or... why use a template then.
I've tied this and created 2 scripts, one that disables and one that enables.
Script 1.
$(document).ready(function(){
$('.elements').attr('readonly',true);
$('.elements').prop('disabled',true);
});
Script 2.
$(document).ready(function(){
$('.elements').attr('readonly',false);
$('.elements').prop('disabled',false);
});
Then I stored those scripts in assets\javascript.
It worked good in show but both edit and create went read-only too.
It seems like everything that is put in this directory is automatically used in each form, because even though I removed the call from the forms, it was working.
Here I show where I originally added the script-call:
<asset:javascript src="myScript_1.js"/>
</body>
</html>
I was going to add it as a comment but then it started to get long and complicated to follow.
why store it in assets ?
simply add a function block to the templates that need it
_template1.gsp
<script>
$(document).ready(function(){
setReadOnly('${someDefinition}')
function setReadOnly(value) {
if (value==='READONLY') {
$('.elements').attr('readonly',true).prop('disabled',true);
}
}
})
</script>
If this function needs to be shared by a bunch of pages, you could add it to an assets / javascript file but rather than declare it in application.js call the js file <asset:javascript tags specificially on each page
and maybe a variable that you pass to template to say when it should be called
or put that above template1 as a master template and call in each of the other templates that needs the js file (So many options)
Now on the main controller doing action
def MyController {
def view() {
String mode='READONLY'
render view: 'index', model:[instance:params,mode:mode]
}
}
the in index.gsp
if js is there then it will pick up mode and set readonly for that controller action or pass that from one template to another, the controller does not have to define actual mode, the main master view page or index page could define mode too
Maybe you need to play/understand then implement you can't rush these things otherwise you will end up wasting time and rewriting
Just to ensure we are on the same page.
By default the application.js file in the javascript folder has a tree line enabled - this by default then reads in all js files. If you wish to manually call js in different places you will need to remove this line and declare each and every js file that you use like the other lines provided in that file.
So that is the price to pay (no more auto loading js files) until declared in application.js
But then most importantly as you have noticed these are global js functions and really nothing new should be going in there that hasn't got a function something() { } a function call.
They will then react when the actual function is called rather than how you had it which was open for call from any old page since it happened as documents opened regardless
I've worked a while now with Backbone.js, and one of the things I nowadays run into is; Sometimes you need to have serverside logic into a .eco.jst template
For example
an i18n translation (currently look at i18n.js gem for this)
a path a route without hardcoding it (somemodel_path(somemodel))
authorisation (for example, show a delete button if the user can destroy this model). Atm I solve this by passing in some rights object in the json that gets filled in.
Rendering a html helper like simple_form or S3_file_uploader (atm I solve this with rendering it serverside, and put the display on none)
As you know, .eco get parsed by node.js, so I can't call ruby in the eco files. Most of these problems I solve by basicly creating a "data" object in the head. Similar to this:
window.data = {
some_translation = "<%= t('cool') %>",
<%= "can_destoy_model = true," if can?('destroy', Model) %>
post_edit_link = "<%= post_path(#post) %>
}
Besides this being bulky (this is just an example, normally this would be more ordened or I add a html5 data attribute to some dom element), It's time consuming, sometimes you have to recreate complete business logic which otherwise would be a oneliner in rails (take for example the S3_file_uploader, which requires encoded amazon policyfile and a token)
What are your thoughts about this? Should I perhaps not use .eco (although I like templates in seperate files instead of poluting the view). Would I able to use serverside logic if I for instance used mustache or handlebars and which gem would you recommend if so?
My experience with Backbone.js is kind of limited, but I've managed to setup an environment with logic-less templates using the following gems:
handlebars_assets
haml_assets
And a bunch of other stuff, even a mini-framework I'm currently working on (you can find it here)
I picked this approach for building Single Page Applications using Backbone.
Basically, the haml_assets gem provides sprockets with the ability to parse .haml files, this is not needed but I love HAML syntax. The handlebars_assets gem provides means to parse Handlebars templates, both on the server-side and the client-side. You can use Ruby code inside the templates and you would solve both the i18n and the path methods problems you mentioned.
I've found these tools to be excellent to help DRY an application's templates, and it can really save you from adding logic inside templates. If you use Backbone Views to take, for example, decisions on whether to show a delete button or not, you can keep the logic inside the Backbone View, and use that logic to render the proper Handlebars template (or partial).
Using your example:
Coffeescript:
class ProjectShowView extends Backbone.View
template: (context) -> HandlebarsTemplates['projects/show'](context)
deleteButtonTemplate: (context) -> HandlebarsTemplates['projects/shared/delete_button'](context)
render: (canDelete = false) ->
#$el.html(#template(#model.toJSON()))
#$('.delete_button_container').append(#deleteButtonTemplate()) if canDelete
#
The example is quite primitive and basic, but can hopefully point in the right direction. I hope it helps!
I think I'm trying to use Backbone in an unintended way, and I couldn't really find much on it. Basically I have a Rails app that is serving up the views. I want to keep the regular navigation (as in page reloading), but let backbone see the route and setup certain parts of the templates on that page, handle the models, and all of that good stuff. So basically I'm using Backbone to handle all of my complicated javascript without making it a "single page app". Would enabling PushState break my absolute paths in older browsers? eg: "http://localhost:3000/projects" matching the route "projects".
PushState will not work in old browsers like IE6, but you could use different technique, for example you could use jQuery selectors and check whether you're on the particular page:
if ($('#login-page').length > 0) {
// we're on the login page
// ..initialize login page related backbone collections and views
}
..or you could store action/controller name somewhere in the html using data attribute: <body data-action="edit" data-controller="post"> and check it in javascript va4 $body = $('body'); if ($body.data('action') == 'edit' && $body.data('controller') == 'posts') {} etc.
..or you could have separate js file for each action/controller pair and include it on demand.
I'm trying to get the hang of the whole asset pipeline thing, and read the guide and several tutorials about them. But one thing that doesn't become quite clear is wether I should view my javascript asset files as a library or a place to put code that is actually run i.e. $(document).ready. Because by default all the javascript files are included, and it would be weird to have several $(document).ready's in there, not to mention that you don't want the $(document).ready function for every page to be run in the first place. What would be the way to go at this? Use my asset files as a library and put actual calls in my views (ugly)? Or is there a better way to do this?
I too ran into this issue. In a large project you can have somebody put code into document ready to, for example, add a click function to each li within a div with class container.
Now we could all argue that the above code would be too generic and of course may affect li tags in other parts of the application, but the bigger the project, the more likely it is that you will run into a conflict like this leading to unexpected behaviour.
I for one am uncomfortable with a whole bunch of document ready functions running for each and every page loaded. My solution is not necessarily the perfect one, but it's one that I have taken up and will share with you.
In the body tag of each page I add data elements signifying the controller and the action. I then have one document ready script that looks for a class named after the controller with the name Ready appended e.g. HomeReady. It will then call a method on this class (presuming it exists) named after the action. So in your asset coffee file you could write:
class #HomeReady
#index: ->
alert("Hello")
#show: ->
alert("Goodbye")
This allows control right down to the action level. When I came across your question I decided to package this solution into a gem as I have already used it in several projects. You can find it at: https://github.com/intrica/rails_document_ready
If you absolutely don't want a certain piece of initialization code to be run unless the current page is a specific controller/action, then you can try adding an empty element on the page with an id built from that info like "posts_index" using these two helpers:
"#{controller_name}_#{action_name}"
Then in your javascript you can wrap the code inside an if statement that checks for the existence of an element with the appropriate id.
edit: Here's an example of the js partial that I mentioned in the comments.
show.html.haml
= render 'map'
map.html.erb (I normally use haml but it's easier to write js in erb)
<script src='http://www.google.com/jsapi' type='text/javascript'></script>
<script type='text/javascript'>
...
</script>
It's probably not as clean as it could be and it doesn't get the benefits of being part of the asset pipeline but I don't mind because it's only something that gets included on a specific page.
We have an editor template that contains approx 40 lines of jquery. I tried dropping this script into a <asp:Content> block to keep all of the javascript in one location within the page. However, I get the following error message content controls have to be top-level controls in a content page.
Is there any way to get this working so we don't have script dotted around our final output pages or could someone recommend the best practice for storing javascript used within ASP.NET MVC templates? At the moment I'm thinking of pulling the code into a separate file and referencing it within the master page but this means it gets pulled into every page which isn't really ideal.
Thanks in advance.
It would be easier for later maintenance, if you keep the javascript into a separate file and reference it where ever it is needed. Also, if you feel that placing all script into a single file will increase unnecessary loading of scripts, where not needed, then break the scripts into separate files based on functionality/modules in which it is useful etc. strategy and then reference them instead.
Also, it was said that always, keep/reference the scripts at the bottom of the page so that page loading will be faster.
as siva says, bottom of the page is the 'ideal'. however, as for seperate files. this is only going to be practical as long as you don't reference asp.net elements from the page - ie:
<asp:Content ContentPlaceHolderID="jsCode" ID="jsCode1" runat="server">
<script type="text/javascript">
$(document).ready(function() {
getPoundsData();
});
function getPoundsData() {
var id = $("#ID").val();
var URL = '<%=Url.Action("GetPounds", "FundShareholder")%>';
var params = { id: id };
if (id != null)
SendAjaxCache("#" + $("#ShareholderID option:selected").text() + " RSP#", URL, params, null, ListDataShareholderPounds);
}
function ListDataShareholderPounds(data) {
if (data.length != 0) {
$('#shareholderPounds').html("");
$('#shareholderPounds').show();
$('#shareholderPounds').html(data);
}
};
</script>
</asp:Content>
notice the:
var URL = '<%=Url.Action("GetPounds", "FundShareholder")%>';
part in the js. what 'we' do is to add a content section to the master page at the very bottom to hold our js stuff. however, this only works inside the ViewPage (aspx) object. the ascx pages are 'ignorant' of any master page content sections.
We are currently working on systemizing the process whereby we save 'partial' js files with asp.net references inside them and then inject them into the page-flow via a filterattribute. we're at an early stage with this but the nice thing about this approach is that the partial js is treated as a file and is therefore cached for future visits to that page.
anyway, that's our current approach, would be interested to discover if peeps are using any similar mechanisms to inject js that contains asp.net object references.
cheers...
[edit] - here's a heads up on the approach i'm talking about (this wasn't our original inspiration, but is quite similar, tho is webforms, rather than mvc) - http://www.west-wind.com/WebLog/posts/252178.aspx or this one which IS mvc: http://poundingcode.blogspot.com/2009/12/injecting-javasript-into-aspnetmvc-with.html.
Finally found the article that inspired our 'search' in this: ASP.NET MVC routing and paths is js files plus http://codepaste.net/p2s3po