NodeJS + JSON + jQuery: send JSON-object form Node-backend to jQuery-frontend

Question

I'm trying to send JSON-object form MongoDB to page with ejs template engine. Here's the response form my DB (a JSON-object):

"suppliers": [
    {
        "lastname": "lastname1",
        "firstname": "firstname1",
        "middlename": "middlename1",
        "mobtel": "mobtel1",
        "worktel": "worktel1",
        "email": "email1"
    },
    {
        "lastname": "lastname2",
        "firstname": "firstname2",
        "middlename": "middlename2",
        "mobtel": "mobtel2",
        "worktel": "worktel2",
        "email": "email2"
    }
]

As I get i from DB as an object, I have to stringify it to str to send as a var for EJS Template engine:

var myJSONText = JSON.stringify(doc.suppliers);
profile["suppliers"] =myJSONText;
...
res.render('profile.ejs',{profile:profile});

On front-end I get a plain string with json-data. I parse it via jQuery to an object:

var jsonObject = jQuery.parseJSON('<%= profile.suppliers %>');
for (var i=0; i<jsonObject.length; i++){
    //trying to show field 'name' for every supplier
    alert(jsonObject[i]['lastname']);
}

...and it doesnt work, but should to alert me twice. I've tried to inspect a plain-text JSON-string, comming to front-end, and found out such symbols:

[{&quot;lastname&quot;: &quot; ...

It seems that jQuery.parseJSON is not able to create a valid object from such string. What I'm doing wrong? Thanks!

UPDATE: Well, I've turned my code into:

NodeJS code:

profile["suppliers"] =doc.suppliers;
res.render('profile.ejs', { profile:profile });

jQuery code:

for (var i=0; i<'<%= profile.suppliers %>'.length; i++){
//trying to show field 'name' for every supplier
alert('<%= profile.suppliers %>'[i]['lastname']);
}

and it gives me never-ending loop of undefined alerts.

UPDATE 2: I've updated my source code, so:

NodeJS:

var myJSONText = JSON.stringify(doc.suppliers);
profile["suppliers"] =myJSONText;
res.render('profile.ejs',{profile:profile});

Client:

var jsonObject = <%- profile.suppliers %>;
$.each(jsonObject, function(item) {
    alert(item.lastname);
});

Generated source code:

var jsonObject = [{"lastname":"lastname1","firstname":"firstname1","middlename":"middlename1","mobtel":"mobtel1","worktel":"worktel1","email":"email1"},{"lastname":"lastname2","firstname":"firstname2","middlename":"middlename2","mobtel":"mobtel2","worktel":"worktel2","email":"email2"}];

Seems to be ok, but still gives me undefined alerts. Hoever, it alerts only twice, that means that it parses JSON correctly and just cannot get access to lastname property?

Why do you have to stringify your JSON in the first place? EJS should handle the object fine. — Wes Johnson
– Wes Johnson, Commented Jun 11, 2012 at 20:01
@WesJohnson: It needs to be stringified so that it can be inserted into the javascript file. However, it does not need to be parsed at the other end. — Eric
– Eric, Commented Jun 11, 2012 at 20:27
This part of your code is broken: i<'<%= profile.suppliers %>'.length. You're iterating over the length of a string, not an array of objects. — Wes Johnson
– Wes Johnson, Commented Jun 11, 2012 at 20:39

Eric · Accepted Answer · 2012-06-11 20:27:07Z

9

As you correctly diagnosed, "s are being inserted into your JSON. This renders it invalid, preventing it being decoded.

This is because in ejs, <%= ... %> does html output escaping, hence the ". You need to use <%- profile.suppliers %> to avoid this.

There's no need to use JSON.parse on the client: JSON is already valid javascript code, so can be inserted straight into the code, rather than being stored as a string literal.

var jsonObject = <%- profile.suppliers %>;
$.each(jsonObject, function() {
    alert(this.lastname);
});

edited Jun 11, 2012 at 20:27

answered Jun 11, 2012 at 20:21

Eric

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7 Comments

f1nn Over a year ago

Thank you, I'll try your solution if Wes' and Terry's variant without stringifying object to plain text will not work

f1nn Over a year ago

Thanks, I got it, however it doesn't work. If I use your code directly, script doesn't work. If I use quotes (var jsonObject = '<%- profile.suppliers %>';), it still gives me an never-ending loop of undefined alerts.

f1nn Over a year ago

Let me note, that I dont stringify object on backend-side now

f1nn Over a year ago

Oh, I've just saw your comment that I must stringify JSON-object.

Eric Over a year ago

@IlyaRusanen: Does it work now then? Have a look at the source code it generates if it doesn't.

|

Terry · Accepted Answer · 2012-06-11 20:17:39Z

0

As Wes is eluding to, I think you're doing unnecessary stringifying/parsing.

Try this:

var suppliers = // your JSON source

$(suppliers).each(function() {
   alert(this.lastname);
});

answered Jun 11, 2012 at 20:17

Terry

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3 Comments

f1nn Over a year ago

I've tried var suppliers = '<%= profile.suppliers %>'; $(suppliers).each(function() { alert(this.lastname); }); but no luck :(

Terry Over a year ago

I'm not familiar with ejs, but if Eric's suggestion works I would expect the code I posted to parse it correctly.

f1nn Over a year ago

Oh, I didn't see Eric's comment about the necessity of stringifying my object.

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