Add object to JSON file before ]

Question

It's probably something ridiculous I'm missing out, but when I add an object to my json file with NodeJs it adds it (obviously?) at the end of the file and so after ]

var file = './data/questions.json';    
fs.appendFile(file, ', ' + JSON.stringify(req.body), function (err) {
    console.log(err);
});

result is something like this:

[
{'id':1, 'name':'Tom'}
], {'id':2, 'name':'Jerry'}

The result seems to be good for me. Do you have the full code? — Praveen Kumar Purushothaman, Jan 15 '16 at 14:10
You would be better off parsing the JSON, modifying the object and then restringing it. — alex, Jan 15 '16 at 14:11
It's doing exactly what you are asking it to. You need to actually parse the js, add the object, then stringify it again and save it to the file. — James Coyle, Jan 15 '16 at 14:12
Obviously it's doing what I tell it to do, that's why I'm here: to ask what I'm doing wrong. — Greg, Jan 15 '16 at 14:14
This might help you http://stackoverflow.com/questions/18884840/adding-a-new-array-element-to-a-json-object — Simon Legg, Jan 15 '16 at 14:15
@Greg Please show more code. What is the input (`req.body`)? — Maru, Jan 15 '16 at 14:16
@MarcoAlka Judging by the result `req.body` is `{'id':2, 'name':'Jerry'}` — Simon Legg, Jan 15 '16 at 14:18
The one that is added after `]`obviously. I wouldn't worry about the `req.body` it's a valid `object` that is added to the `JSON` file but at the wrong place — Greg, Jan 15 '16 at 14:18
@PraveenKumar I'm trying at the moment, I'll give update in a sec — Greg, Jan 15 '16 at 14:23

Praveen Kumar Purushothaman · Accepted Answer · 2016-01-15T14:57:28.120

6

If the file already has an array in it already, what you need is:

var file = './data/questions.json';
// get the contents of the file
var fileContents = do_something_to_get_contents;
// convert to js object
fileContents = JSON.parse(fileContents);
// push the array
fileContents = fileContents.push(req.body);
// update the file contents by stringify
fs.replaceFile(file, JSON.stringify(fileContents), function (err) {
    console.log(err);
});

I am not so good in Node JS. So I am assuming the following:

do_something_to_get_contents gets the file contents.
replaceFile Replace this with a function that writes fresh contents to the file.

edited Jan 15 '16 at 14:57

answered Jan 15 '16 at 14:16

Praveen Kumar Purushothaman

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I think it's fine that you're not good with node.js if the OP didn't have any node code. – Blubberguy22 Jan 15 '16 at 14:17
@Blubberguy22 Thanks buddy... `:)` – Praveen Kumar Purushothaman Jan 15 '16 at 14:18
@Greg Did you just copy and paste? – Praveen Kumar Purushothaman Jan 15 '16 at 14:43
I did most of the parts, except where I had to "do something" – Greg Jan 15 '16 at 14:45
@Greg `fs.replaceFile` is pseudo too! Kindly replace that with the real function... – Praveen Kumar Purushothaman Jan 15 '16 at 14:46
You're not 'so good in Node Js' yet give me a solution full of pseudos. I'm as new to Node as you so how should I know what's right and wrong. – Greg Jan 15 '16 at 14:52
@Greg You must read the **two points** that say: `So I am assuming the following:` It clearly mentions: `do_something_to_get_contents` and `replaceFile` are pseudo codes!!! Can't you even understand that? – Praveen Kumar Purushothaman Jan 15 '16 at 14:53
To me that reads: "replaceFile: the function that writes contents to the file" – Greg Jan 15 '16 at 14:55
@Greg Really sorry. I will update it to make it clear. – Praveen Kumar Purushothaman Jan 15 '16 at 14:57
@Greg Any positive news? Updates? – Praveen Kumar Purushothaman Jan 15 '16 at 15:22

Blubberguy22 · Answer 2 · 2016-01-15T14:24:07.537

2

You need to parse the JSON file to add to it. Try something like this:

var file = './data/questions.json';
var fileData = get_data_from_file
var jData = JSON.parse(file);
jData.push({'id':2, 'name':'Jerry'});
var newFileData = JSON.stringify(jData);
//put the data back into the file

edited Jan 15 '16 at 14:24

answered Jan 15 '16 at 14:17

Blubberguy22

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Er, no. `JSON.parse(file)` will attempt to parse `./data/questions.json`, not the **contents** of the file. You'll need to read it first. And I guess the OP also wants the resulting JSON-encoded data to be written to a file. – jcaron Jan 15 '16 at 14:22
@jcaron Good point, my bad, I didn't notice that. I'll fix it, thanks. – Blubberguy22 Jan 15 '16 at 14:23

Add object to JSON file before ]

2 Answers2