How do i pass jinja2 data into javascript.
I have a Flask REST url as /logs/<test_case_name>
I am trying use .getJSON() to query the above URL and hence would want to pass the jinja2 data which has the testcasename to .getJSON function.
sample code:
<script type="text/javascript">
alert({{name}});
</script>
It doesn't work.
Any suggestions please?
Try with quotes:
alert("{{name}}");
other than encapsulating the variable in a string, an alternate is jquery for profit:
its generally a bad idea to mix template language with javascript. An alternative would be to use html as a proxy - store the name in an element like so
<meta id="my-data" data-name="{{name}}" data-other="{{other}}">
then in the javascript do
var djangoData = $('#my-data').data();
this has advantage in:
javascript no longer tied to the .html page
jquery coerces data implicitly
I know this is a kinda old topic, but since it attracts a lot of views I suppose some people are still looking for an answer.
Here's the simplest way to do it:
var name = {{name|tojson}};
It will 'parse' whatever 'name' is and display it correctly:
https://sopython.com/canon/93/render-string-in-jinja-to-javascript-variable/
This is how I did it
My html Element
<!--Proxy Tag for playlist data-->
<meta id="my_playlist_data" data-playlist="{{ playlist }}">
My script element
// use Jquery to get data from proxy Html element
var playlist_data = $('#my_playlist_data').data("playlist");
See .data() documenttation for more
I just figure I would add the solution I ended up using.
It has a few advantages over the other answers:
It is 100% valid javascript at the template level (no editor/lint errors).
Does not need any special HTML tag.
No dependencies (jquery, or otherwise).
let data = JSON.parse('{{ data | tojson }}');
you can try alert({{name|safe}});
<input type="hidden" name="token_idx" id="token_idx" value='{{token|safe }}'
let token_data = document.getElementById("token_idx").value;
Related
What is the recommended way to create dynamic URLs in Javascript files when using flask? In the jinja2 templates and within the python views url_for is used, what is the recommended way to do this in .js files? Since they are not interpreted by the template engine.
What basically want to do is:
// in comments.js
$.post(url_for('comment.comment_reply'));
Which is not possible.
But naturally, I can execute that in a template:
<script>
$.post(url_for('comment.comment_reply'));
</script>
What #dumbmatter's suggesting is pretty much considered a de facto standard way. But I thought there would be a nicer way of doing it. So I managed to develop this plugin: Flask-JSGlue.
After adding {{ JSGlue.include() }}, you can do the following in your source code:
<script>
$.post(Flask.url_for('comment.comment_reply', {article_id: 3}));
</script>
or:
<script>
location.href = Flask.url_for('index', {});
</script>
The Flask documentation suggests using url_for in your HTML file to set a variable containing the root URL that you can access elsewhere. Then, you would have to manually build the view URLs on top of that, although I guess you could store them similar to the root URL.
Was searching for a solution, them come up with this solution where
No add-on is required
No hard-coding URL
The key is to realise Jinja2 has the ability to render javascript out of the box.
Setup your template folder to something like below:
/template
/html
/index.html
/js
/index.js
In your views.py
#app.route("/index_js")
def index_js():
render_template("/js/index.js")
Now instead of serving the javascript from your static folder. You would use:
<script src="{{ url_for('index_js') }}"></script>
After all, you are generating the javascript on the fly, it is no longer a static file.
Now, inside of you javascript file, simply use the url_for as you would in any html file.
For example using Jquery to make an Ajax request
$.ajax({
url: {{ url_for('endpoint_to_resource') }},
method: "GET",
success: call_back()
})
#jeremy's answer is correct and probably the more common approach, but as an alternative answer, note that dantezhu wrote and published a flask extension that claims to do the exact url-route-map-to-javascript translation suggested in the comment.
I use this dirty and ugly trick:
"{{url_for('mypage', name=metadata.name,scale=93,group=2)}}"
.replace('93/group',scale+'/group')
where scale is the javascript variable I want to use for an AJAX request.
So, url_for generate an URL and JavaScript replace the parameter at runtime. The generated code is something like:
"/ajaxservive/mynam/scale/93/group/2".replace('93/group',scale+'/group')
which is pretty strange, but still can't find more elegant solutions.
In fact, looking at the code of the linked flask extension, it does the same thing but managing the general case.
In my case,
I was trying to dynamically create urls
I solved my issue as follows (Note: I've swapped out Angular's syntax to {[x]}:
<ul>
<li ng-repeat="x in projects">
{[x.title]}
{% set url = url_for('static',filename="img/") %}
<img src="{{url}}{[x.img]}">
</li>
</ul>
I was able to pass a dynamically created url route to a javascript function by using "tojson" with Jinja2 and Flask.
To pass the dynmaic url from the html template to js, simply add '|tojson' at the end of your jinja statment to convert it to the appropriate format.
Instead of:
<script>
$.post(url_for('comment.comment_reply'));
</script>
Try:
<script>
var route = {{ url_for('comment.comment_reply')|tojson }};
yourJavaScriptFunction(route);
</script>
Then you will be able to use the route in your js functions as the correct route for whatever you need.
yourJavaScriptFunction(route){
console.log(route);
}
I was trying to call a FLASK route when a button is pressed. It should collect the response and update a div. The page should not reload.
I used jquery to do this.
Here's the code:
#app.route('/<name>')
def getContent(name):
return 'This is %s' % name
HTML:
<div id="mySpace" class="my-3">Count</div>
<button id="next_id" class="btn btn-primary">Press</button>
<script>
$('#next_id').click(function (){
$.get('/aroy', function(data, status){
$('#mySpace').html(data);
});
});
</script>
I suggest this:
<script src="{{ url_for('static', filename='js/jquery.js') }}" type="text/javascript">
</script>
Works fine for me
I am completely lost on this; I am using NodeJS to fetch a JSON and I need to pass the variable to my page and have JavaScript use the data.
app.get('/test', function(req, res) {
res.render('testPage', {
myVar: 'My Data'
});
That is my Express code (very simple for testing purposes); now using JADE I want to gather this data which I know to render on the page is simply
p= myVar
But I need to be able to gather this data in JavaScript (if possible within a .js file) but for now just to display the variable in an Alert box I have tried
alert(#{myVar})
And many others if anyone can help be much appreciated
Try the following:
alert('!{myVar}')
It's a good idea to JSON encode the data if is more than just a string.
alert('!{JSON.stringify(myVar)}')
As Timothy said:
<script type="text/javascript"> var myVar = #{JSON.stringify(myVar)}; </script>
This can also be done as follows in if you don't like to write HTML in Jade/Pug templates:
script
var myVar = !{JSON.stringify(myVar)};
var myVar2 = !{JSON.stringify(myVar2)};
Update: For Express 4 and Pug use script. instead of script so that it will be rendered as javascript instead of html.
Well, Javascript (and V8) has a built in function to render JSON from a object, and JSON happens to be syntactially compatible with Javascript.
So the easiest way to do what your trying to do would be:
<script type="text/javascript>var myVar = #{JSON.stringify(myVar)};</script>
And, yes, you can use HTML in a Jade template.
I know I'm a bit late to the party, but I actually wrote a module (JShare) a few months ago to solve this exact problem. Check it out: https://npmjs.org/package/jshare
You could leverage Now.js for this. It easily allows you to share variables client/server side real-time.
Check it out: http://www.nowjs.com/
I'm trying to make a variable (eventually to be replaced by more complex json selected from the database) accessible to client-side javascript. I wanted to load it when the page is rendered instead of an ajax call and its not going to be rendered via a template like ejs (I want to pass the data to an extjs store for a combobox). So I have a standart response I render:
function (req, res) {
res.render('index.html', {foo: ['a','b']});
}
and a blank html page I want to access foo:
<!DOCTYPE html>
<html>
<head>
<script type=text/javascript>
console.log(foo);
</script>
</head>
<body>
</body>
</html>
any ideas? I've thought of maybe writing the whole html page via res.send() (which has a few more things than the example above) but that seems like such a workaround for something that should be obvious to do...
Assuming the same array foo in your question above, here are a couple ways you could do this.
This one uses an EJS filter to write an array literal:
<script type="text/javascript">
var foo = ['<%=: foo | join:"', '" %>'];
</script>
This one encodes it as JSON, to later be parsed by your client-side javascript:
<script type="text/javascript">
// note the "-" instead of "=" on the opening tag; it avoids escaping HTML entities
var fooJSON = '<%-JSON.stringify(foo)%>';
</script>
IIRC, ExtJS can handle JSON directly as its data. If not, then you could use its JSON parser first and then hand it a local variable. If you weren't using ExtJS, you could use this to parse on the client: https://github.com/douglascrockford/JSON-js
If you choose to encode it as JSON, it would make it also make it easier to later switch back to AJAX for retrieving your data. In some cases, that would have an advantage. The page could load and display some data, along with a busy icon over the element for which you're loading data.
This isn't to say there's anything inherently wrong with including all the data in the original request. It's just that sticking with JSON gives you the flexibility to choose later.
In EJS the following should work
<script type=text/javascript>
console.log( <%= foo %>);
</script>
I do recommend against dynamically generating JavaScript though as it breaks seperation of concerns and forces JavaScript to be on.
Edit:
Turns out the above doesn't work nicely for arrays. So simply encode your data in semantic HTML. Then enhance it with JavaScript. If the JavaScript must get data then store it somewhere more sensible like the cookie or retrieve it through ajax.
I'm using Django on Appengine. I'm using the django reverse() function everywhere, keeping everything as DRY as possible.
However, I'm having trouble applying this to my client-side javascript. There is a JS class that loads some data depending on a passed-in ID. Is there a standard way to not-hardcode the URL that this data should come from?
var rq = new Request.HTML({
'update':this.element,
}).get('/template/'+template_id+'/preview'); //The part that bothers me.
There is another method, which doesn't require exposing the entire url structure or ajax requests for resolving each url. While it's not really beautiful, it beats the others with simplicity:
var url = '{% url blog_view_post 999 %}'.replace (999, post_id);
(blog_view_post urls must not contain the magic 999 number themselves of course.)
Having just struggled with this, I came up with a slightly different solution.
In my case, I wanted an external JS script to invoke an AJAX call on a button click (after doing some other processing).
In the HTML, I used an HTML-5 custom attribute thus
<button ... id="test-button" data-ajax-target="{% url 'named-url' %}">
Then, in the javascript, simply did
$.post($("#test-button").attr("data-ajax-target"), ... );
Which meant Django's template system did all the reverse() logic for me.
The most reasonable solution seems to be passing a list of URLs in a JavaScript file, and having a JavaScript equivalent of reverse() available on the client. The only objection might be that the entire URL structure is exposed.
Here is such a function (from this question).
Good thing is to assume that all parameters from JavaScript to Django will be passed as request.GET or request.POST. You can do that in most cases, because you don't need nice formatted urls for JavaScript queries.
Then only problem is to pass url from Django to JavaScript. I have published library for that. Example code:
urls.py
def javascript_settings():
return {
'template_preview_url': reverse('template-preview'),
}
javascript
$.ajax({
type: 'POST',
url: configuration['my_rendering_app']['template_preview_url'],
data: { template: 'foo.html' },
});
Similar to Anatoly's answer, but a little more flexible. Put at the top of the page:
<script type="text/javascript">
window.myviewURL = '{% url myview foobar %}';
</script>
Then you can do something like
url = window.myviewURL.replace('foobar','my_id');
or whatever. If your url contains multiple variables just run the replace method multiple times.
I like Anatoly's idea, but I think using a specific integer is dangerous. I typically want to specify an say an object id, which are always required to be positive, so I just use negative integers as placeholders. This means adding -? to the the url definition, like so:
url(r'^events/(?P<event_id>-?\d+)/$', events.views.event_details),
Then I can get the reverse url in a template by writing
{% url 'events.views.event_details' event_id=-1 %}
And use replace in javascript to replace the placeholder -1, so that in the template I would write something like
<script type="text/javascript">
var actual_event_id = 123;
var url = "{% url 'events.views.event_details' event_id=-1 %}".replace('-1', actual_event_id);
</script>
This easily extends to multiple arguments too, and the mapping for a particular argument is visible directly in the template.
I've found a simple trick for this. If your url is a pattern like:
"xyz/(?P<stuff>.*)$"
and you want to reverse in the JS without actually providing stuff (deferring to the JS run time to provide this) - you can do the following:
Alter the view to give the parameter a default value - of none, and handle that by responding with an error if its not set:
views.py
def xzy(stuff=None):
if not stuff:
raise Http404
... < rest of the view code> ...
Alter the URL match to make the parameter optional: "xyz/(?P<stuff>.*)?$"
And in the template js code:
.ajax({
url: "{{ url views.xyz }}" + js_stuff,
... ...
})
The generated template should then have the URL without the parameter in the JS, and in the JS you can simply concatenate on the parameter(s).
Use this package: https://github.com/ierror/django-js-reverse
You'll have an object in your JS with all the urls defined in django. It's the best approach I found so far.
The only thing you need to do is add the generated js in the head of your base template and run a management command to update the generated js everytime you add a url
One of the solutions I came with is to generate urls on backend and pass them to browser somehow.
It may not be suitable in every case, but I have a table (populated with AJAX) and clicking on a row should take the user to the single entry from this table.
(I am using django-restframework and Datatables).
Each entry from AJAX has the url attached:
class MyObjectSerializer(serializers.ModelSerializer):
url = SerializerMethodField()
# other elements
def get_url(self, obj):
return reverse("get_my_object", args=(obj.id,))
on loading ajax each url is attached as data attribute to row:
var table = $('#my-table').DataTable({
createdRow: function ( row, data, index ) {
$(row).data("url", data["url"])
}
});
and on click we use this data attribute for url:
table.on( 'click', 'tbody tr', function () {
window.location.href = $(this).data("url");
} );
I always use strings as opposed to integers in configuring urls, i.e.
instead of something like
... r'^something/(?P<first_integer_parameter>\d+)/something_else/(?P<second_integer_parameter>\d+)/' ...
e.g: something/911/something_else/8/
I would replace 'd' for integers with 'w' for strings like so ...
... r'^something/(?P<first_integer_parameter>\w+)/something_else/(?P<second_integer_parameter>\w+)/' ...
Then, in javascript I can put strings as placeholders and the django template engine will not complain either:
...
var url = `{% url 'myapiname:urlname' 'xxz' 'xxy' %}?first_kwarg=${first_kwarg_value}&second_kwarg=${second_kwarg_value}`.replace('xxz',first_integer_paramater_value).replace('xxy', second_integer_parameter_value);
var x = new L.GeoJSON.AJAX(url, {
style: function(feature){
...
and the url will remain the same, i.e something/911/something_else/8/.
This way you avoid the integer parameters replacement issue as string placeholders (a,b,c,d,...z) are not expected in as parameters
When I render a page using the Django template renderer, I can pass in a dictionary variable containing various values to manipulate them in the page using {{ myVar }}.
Is there a way to access the same variable in Javascript (perhaps using the DOM, I don't know how Django makes the variables accessible)? I want to be able to lookup details using an AJAX lookup based on the values contained in the variables passed in.
The {{variable}} is substituted directly into the HTML. Do a view source; it isn't a "variable" or anything like it. It's just rendered text.
Having said that, you can put this kind of substitution into your JavaScript.
<script type="text/javascript">
var a = "{{someDjangoVariable}}";
</script>
This gives you "dynamic" javascript.
CAUTION Check ticket #17419 for discussion on adding similar tag into Django core and possible XSS vulnerabilities introduced by using this template tag with user generated data. Comment from amacneil discusses most of the concerns raised in the ticket.
I think the most flexible and handy way of doing this is to define a template filter for variables you want to use in JS code. This allows you to ensure, that your data is properly escaped and you can use it with complex data structures, such as dict and list. That's why I write this answer despite there is an accepted answer with a lot of upvotes.
Here is an example of template filter:
// myapp/templatetags/js.py
from django.utils.safestring import mark_safe
from django.template import Library
import json
register = Library()
#register.filter(is_safe=True)
def js(obj):
return mark_safe(json.dumps(obj))
This template filters converts variable to JSON string. You can use it like so:
// myapp/templates/example.html
{% load js %}
<script type="text/javascript">
var someVar = {{ some_var | js }};
</script>
A solution that worked for me is using the hidden input field in the template
<input type="hidden" id="myVar" name="variable" value="{{ variable }}">
Then getting the value in javascript this way,
var myVar = document.getElementById("myVar").value;
As of Django 2.1, a new built in template tag has been introduced specifically for this use case: json_script.
https://docs.djangoproject.com/en/stable/ref/templates/builtins/#json-script
The new tag will safely serialize template values and protects against XSS.
Django docs excerpt:
Safely outputs a Python object as JSON, wrapped in a tag,
ready for use with JavaScript.
There is a nice easy way implemented from Django 2.1+ using a built in template tag json_script. A quick example would be:
Declare your variable in your template:
{{ variable|json_script:'name' }}
And then call the variable in your <script> Javascript:
var js_variable = JSON.parse(document.getElementById('name').textContent);
It is possible that for more complex variables like 'User' you may get an error like "Object of type User is not JSON serializable" using Django's built in serializer. In this case you could make use of the Django Rest Framework to allow for more complex variables.
new docs says use {{ mydata|json_script:"mydata" }} to prevent code injection.
a good exmple is given here:
{{ mydata|json_script:"mydata" }}
<script>
const mydata = JSON.parse(document.getElementById('mydata').textContent);
</script>
For a JavaScript object stored in a Django field as text, which needs to again become a JavaScript object dynamically inserted into on-page script, you need to use both escapejs and JSON.parse():
var CropOpts = JSON.parse("{{ profile.last_crop_coords|escapejs }}");
Django's escapejs handles the quoting properly, and JSON.parse() converts the string back into a JS object.
Here is what I'm doing very easily:
I modified my base.html file for my template and put that at the bottom:
{% if DJdata %}
<script type="text/javascript">
(function () {window.DJdata = {{DJdata|safe}};})();
</script>
{% endif %}
then when I want to use a variable in the javascript files, I create a DJdata dictionary and I add it to the context by a json : context['DJdata'] = json.dumps(DJdata)
Hope it helps!
For a dictionary, you're best of encoding to JSON first. You can use simplejson.dumps() or if you want to convert from a data model in App Engine, you could use encode() from the GQLEncoder library.
Note, that if you want to pass a variable to an external .js script then you need to precede your script tag with another script tag that declares a global variable.
<script type="text/javascript">
var myVar = "{{ myVar }}"
</script>
<script type="text/javascript" src="{% static "scripts/my_script.js" %}"></script>
data is defined in the view as usual in the get_context_data
def get_context_data(self, *args, **kwargs):
context['myVar'] = True
return context
I was facing simillar issue and answer suggested by S.Lott worked for me.
<script type="text/javascript">
var a = "{{someDjangoVariable}}"
</script>
However I would like to point out major implementation limitation here.
If you are planning to put your javascript code in different file and include that file in your template. This won't work.
This works only when you main template and javascript code is in same file.
Probably django team can address this limitation.
I've been struggling with this too. On the surface it seems that the above solutions should work. However, the django architecture requires that each html file has its own rendered variables (that is, {{contact}} is rendered to contact.html, while {{posts}} goes to e.g. index.html and so on). On the other hand, <script> tags appear after the {%endblock%} in base.html from which contact.html and index.html inherit. This basically means that any solution including
<script type="text/javascript">
var myVar = "{{ myVar }}"
</script>
is bound to fail, because the variable and the script cannot co-exist in the same file.
The simple solution I eventually came up with, and worked for me, was to simply wrap the variable with a tag with id and later refer to it in the js file, like so:
// index.html
<div id="myvar">{{ myVar }}</div>
and then:
// somecode.js
var someVar = document.getElementById("myvar").innerHTML;
and just include <script src="static/js/somecode.js"></script> in base.html as usual.
Of course this is only about getting the content. Regarding security, just follow the other answers.
I have found we can pass Django variables to javascript functions like this:-
<button type="button" onclick="myJavascriptFunction('{{ my_django_variable }}')"></button>
<script>
myJavascriptFunction(djangoVariable){
alert(djangoVariable);
}
</script>
I use this way in Django 2.1 and work for me and this way is secure (reference):
Django side:
def age(request):
mydata = {'age':12}
return render(request, 'test.html', context={"mydata_json": json.dumps(mydata)})
Html side:
<script type='text/javascript'>
const mydata = {{ mydata_json|safe }};
console.log(mydata)
</script>
you can assemble the entire script where your array variable is declared in a string, as follows,
views.py
aaa = [41, 56, 25, 48, 72, 34, 12]
prueba = "<script>var data2 =["
for a in aaa:
aa = str(a)
prueba = prueba + "'" + aa + "',"
prueba = prueba + "];</script>"
that will generate a string as follows
prueba = "<script>var data2 =['41','56','25','48','72','34','12'];</script>"
after having this string, you must send it to the template
views.py
return render(request, 'example.html', {"prueba": prueba})
in the template you receive it and interpret it in a literary way as htm code, just before the javascript code where you need it, for example
template
{{ prueba|safe }}
and below that is the rest of your code, keep in mind that the variable to use in the example is data2
<script>
console.log(data2);
</script>
that way you will keep the type of data, which in this case is an arrangement
There are two things that worked for me inside Javascript:
'{{context_variable|escapejs }}'
and other:
In views.py
from json import dumps as jdumps
def func(request):
context={'message': jdumps('hello there')}
return render(request,'index.html',context)
and in the html:
{{ message|safe }}
There are various answers pointing to json_script. Contrary to what one might think, that's not a one size fits all solution.
For example, when we want to pass to JavaScript dynamic variables generated inside a for loop, it's best to use something like data-attributes.
See it in more detail here.
If you want to send variable directly to a function by passing it as a parameter then try this
<input type="text" onkeyup="somefunction('{{ YOUR_VARIABLE }}')">
As from previous answers the security can be improved upon