d3 js - loading json without a http get

Question

I am learning d3. There are certain ways of loading the data in d3 js. But all of them seem to make a HTTP GET. In my scenario, I already have the json data in a string. How can I use this string instead of making another http request? I tried to look for documentation for this but found none.

This works:

d3.json("/path/flare.json", function(json) {
    //rendering logic here
}

Now, if I have:

//assume this json comes from a server (on SAME DOMAIN)
var myjson = '{"name": "flare","children": [{"name": "analytics","children": [{"name": "cluster","children": [{"name": "MergeEdge", "size": 10 }]}]}]}'; 

How do I use already computed 'myjson' in d3 & avoid a async call to server? Thanks.

Manicdepressive

What is it that you want to do with the object? Also, why would you hard-code that as a string instead of as a plain JavaScript object? – Rupert

@Rupert The server returns it as a model attribute in the response. So I have the string. For eg, the json I have corresponds to the code in mbostock.github.com/d3/ex/bubble.html Thats the logic that goes in there – Manicdepressive

See also #20941354 – Marginalia

Answer 1

Simply replace d3.json call with

json = JSON.parse( myjson );

IE:

var myjson = '{"name": "flare","children": [{"name": "analytics","children": [{"name": "cluster","children": [{"name": "MergeEdge", "size": 10 }]}]}]}';

// d3.json("/path/flare.json", function(json) { #delete this line

    json = JSON.parse( myjson ); //add this line

    //rendering logic here

//} #delete this line

UPDATE 09/2013

Original code has changed. So varname json should be root:

// d3.json("flare.json", function(error, root) { #delete this line

    root = JSON.parse( myjson ); //add this line

    //rendering logic here

//} #delete this line

Lickspittle

Got that part. Can you let me know how to use this parsed 'json' object to render the graph (without making a GET reqeust) found here mbostock.github.com/d3/ex/bubble.html The example uses d3.json("../data/flare.json", function(json) which makes a http call. Any pointers to docs/examples will help too. Thanks. – Manicdepressive

@Manicdepressive replace line 14 with json = JSON.parse( myjson ); and delete line 33. Try it – Lickspittle

Tried it. Worked perfectly! Now I see what is happening... Thank you!! – Manicdepressive

Thanks, I had similar situation. Of course obvious now that it works but your guidance was helpful since I am still getting my bearings with d3. – Jablonski

wait, how exactly is the variable json being passed to d3 library? Can you explain what is happening here? – Tace

The original comment wasn't clear, but the new variable "json" takes the place of the "graph" variable in the callback 'function(error, graph)'. – Hypoplasia

All this code does is it tells you how to parse a json string to a json object. If you want to see how to tie that data with d3, see @dardo's answer below. – Works

Answer 2

The answer from chumkiu worked great for me but needed a couple of tweaks - in the latest version of the d3 bubble chart, you need to define root rather than json, as in

 root = JSON.parse( myjson );

Alternatively, you could replace "root" with "json" in the rest of the code of course. :-)

For anyone coming to this answer with questions about d3 node-link trees that utilize local data sets, this answer worked great for me - many thanks to the contributors on this page.

Heparin

Answer 3

According to this example:

http://phrogz.net/JS/d3-playground/#StockPrice_HTML

Here they are storing the graph data within the variable $data, and setting it via the .data($data) function.

I'd apply this method to whatever graph you are using.

Obelia

This might work; They have a similar example here: github.com/mbostock/d3/wiki/Selections#wiki-data – Tace