Develop Reference

JSON to JS with Django: SyntaxError: missing : after property id

I'm attempting to get a JSON file into a script. I can't seem to be able to get it there by serving it from the filesystem so I made a view that returns the JSON data to the page like so:
def graph(request, d): #d.data is the file in the database
data = json.load(d.data)
return render(request, 'temp/template.html', {'json': data})
In my JS:
var j = {{ json|safe }};
When I look at the source for the JS it shows the data in this format:
{u'people': [{u'name': u'steve'}, {u'name': u'dave'}]}
Which I read shouldn't be a problem. I don't have any variables called 'id' and yet I get the error in the title pointing to the provided line of JS.
Why could this be? Also how do I then use the objects from the JSON in my script?

Solved by using simplejson:
import simplejson as json
And everything else as above. This is because the built in json.dumps returns an array of unicode like:
{u'people': [{u'name': u'steve'}, {u'name': u'dave'}]}
When using simplejson that shouldn't be a problem.

passing JSON data and getting it back

I'm new to passing objects through AJAX, and since I am unsure of both the passing and retrieving, I am having trouble debugging.
Basically, I am making an AJAX request to a PHP controller, and echoing data out to a page. I can't be sure I'm passing my object successfully. I am getting null when printing to my page view.
This is my js:
// creating a js filters object with sub arrays for each kind
var filters = {};
// specify arrays within the object to hold the the list of elements that need filtering
// names match the input name of the checkbox group the element belongs to
filters['countries'] = ["mexico", "usa", "nigeria"];
filters['stations'] = ["station1", "station2"];
filters['subjects'] = ["math", "science"];
// when a checkbox is clicked
$("input[type=checkbox]").click(function() {
// send my object to server
$.ajax({
type: 'POST',
url: '/results/search_filter',
success: function(response) {
// inject the results
$('#search_results').html(response);
},
data: JSON.stringify({filters: filters})
}); // end ajax setup
});
My PHP controller:
public function search_filter() {
// create an instance of the view
$filtered_results = View::instance('v_results_search_filter');
$filtered_results->filters = $_POST['filters'];
echo $filtered_results;
}
My PHP view:
<?php var_dump($filters);?>
Perhaps I need to use a jsondecode PHP function, but I'm not sure that my object is getting passed in the first place.

IIRC the data attribute of the $.ajax jQuery method accepts json data directly, no need to use JSON.stringify here :
data: {filters: filters}
This way, you're receiving your json data as regular key/value pairs suitable for reading in PHP through the $_POST superglobal array, as you would expect.

http://blog.teamtreehouse.com/beginners-guide-to-ajax-development-with-php
When you use ajax the page is not reloaded so the php variable isn't of use.
You may want to look for a tutorial to help. I put one at the beginning as I don't see how to format this on my tablet
you will need to json_encode your response as the tutorial shows
you may want to print to a log on the server when you are in the php function and make it world readable so you can access it via a browser
I like to use the developer tools in Chrome to see what is actually returned from the server

using and storing json text in JavaScript

I'm making a 2D, top-down Zelda-style web single player rpg...
I'd like to store dialog in JSON format...
Currently I'm getting the json as an external javascript file. The json is stored as such in js/json.js:
function getJson() {
var json = {
"people" :
[
{//NPC 1 - rescue dog
etc...
Then I use it in my main game javascript file as such <script src="js/json.js"></script>..`
var json = getJson();
Then use it as such:
Labels[index].text = json.people[index].dialogs.start.texts[0];
Does it matter if I keep the json as a js file in a javascript function? Or should it be stored as a .txt file then parsed?
Thanks!

It does not matter but JSON data is also JavaScript so store it as .js and later on you can add more data related functions to it if needed, btw your data file already has a getJSON function so it doesn't make sense to store it as .txt
On the other hand if an API is serving this data it need not have any extension at all.

It's better off storing the data in pure JSON format and retrieving it via jQuery.getJSON() or an XMLHttpRequest, if you're using vanilla JavaScript. Otherwise, it looks like you're adding getJson() to the global scope, which may result in a conflict if you have another getJson() defined elsewhere.
So you could have a dialog.json that looks almost the same as what you have now, just without the unnecessary getJson() function:
{
"people" :
[
{//NPC 1 - rescue dog
...
}
]
}
If you choose to use jQuery:
var dialog;
$.getJSON('json/dialog.json', function(data) {
dialog = data;
// Asynchronous success callback.
// Now dialog contains the parsed contents of dialog.json.
startGame();
});
Keeps your data separate from your logic.

Passing Python Objects to JavaScript through Django Template Variable

I have been able to pass primitive types such as integers like this, but I would like to pass more complicated objects, such as some the Django models that I have created. What is the correct way of doing this?

I know I'm a little late to the party but I've stumbled upon this question in my own work.
This is the code that worked for me.
This is in my views.py file.
from django.shortcuts import render
from django.http import HttpResponse
from .models import Model
#This is the django module which allows the Django object to become JSON
from django.core import serializers
# Create your views here.
def posts_home(request):
json_data = serializers.serialize("json",Model.objects.all())
context = {
"json" : json_data,
}
return render(request, "HTMLPage.html",context)
Then when I'm accessing the data in my html file it looks like this:
<script type = 'text/javascript'>
var data = {{json|safe}}
data[0]["fields"].ATTRIBUTE
</script>
data is a list of JSON objects so I'm accessing the first one so that's why it's data[0]. Each JSON object has three properties: “pk”, “model” and “fields”. The "fields" attribute are the fields from your database. This information is found here: https://docs.djangoproject.com/es/1.9/topics/serialization/#serialization-formats-json

For Django model instances in particular, you can serialize them into JSON and use the serialized value in your template context.
From there, you can simply do:
var myObject = eval('(' + '{{ serialized_model_instance }}' + ')');
or
var myObject = JSON.parse('{{ serialized_model_instance }}');
if using JSON-js (which is safer).
For Python objects in general see How to make a class JSON serializable

passing an javascript object from cakephp view to controller

I am developing a website using cakephp, and I'd like to pass a javascript object in view back to the controller. I know that using a form could be easier but I need to do this customized.
So here's the object ('annotation' and 'article_id' are real column names in the database, annotation and article_id are both variables containing data):
var postdata = {
'annotation' : annotation,
'article_id' : article_id
};
What method in the view should I use? Is it .post?
And how should I program the corresponding controller to correctly receive the object and extract data from it?

You probably want to do an ajax request.