JSON query not working - 'Cannot read property '0' of undefined'

Coding Help
1

I have this code:

var options = { method: 'POST',
  url: 'https://app.nanonets.com/api/v2/ImageCategorization/LabelUrls/',
  headers:
  { 'cache-control': 'no-cache',
    'Authorization' : 'Basic ' + Buffer.from('MYAPIKEY' + ':').toString('base64'),
    'Content-Type': 'application/x-www-form-urlencoded' },
  form:
  { urls: message.attachments.first().url,
    modelId: '353cea12-4dcc-47ee-b139-dd345157b17d' } };

request(options, function (error, response,body) {
  if (error) throw new Error(error);
  console.log(body)
});

An example of what the console.log() shows is:

{"message":"Success","result":[{"message":"Success","prediction":[{"label":"sfw","probability":0.8503612},{"label":"nsfw","probability":0.14963877}],"file":"https://cdn.discordapp.com/attachments/746884075855282249/757723667051577434/B99.png"}]}

But this tells me that it ‘Cannot read property ‘0’ of undefined’:

  if(body.result[0].prediction[0].probability < body.result[0].prediction[1].probability){
	  message.remove()
	  message.channel.send("Please don't send NSFW images!")
  }

(It’s just under the console.log())
I tested with jsonquerytool.com and it’s right, but it gives me an error.
Anyone know how to fix this?
Any answers appreciated in advance :slight_smile:
Eddie

1 Like
2

I tried this:

var a = {
	"message": "Success",
	"result": [{
		"message": "Success",
		"prediction": [{
			"label": "sfw",
			"probability": 0.8503612
		}, {
			"label": "nsfw",
			"probability": 0.14963877
		}],
		"file": "https://cdn.discordapp.com/attachments/746884075855282249/757723667051577434/B99.png"
	}]
}

console.log(a["result"][0]["prediction"][0]["probability"]) //sfw probability, 0.8503612

Is there any way to JSONify the response body so the keys aren’t strings? Having all these brackets is kind of a pain…

3

Thanks for the speedy response :+1: :running_man:
Will try this out tomorrow. I assume the tool I used did what you suggested and somehow JSONified what I gave :slight_smile:

1 Like
4

What you need to figure out is the structure of the response body, which parts are a javascript object and which parts are a JSON string, which look like a javascript object when showing in the log.

For example, if the entire body is a string, you can do

bodyObj = JSON.parse(body)
bodyObj.result[0].prediction[0].probability

If body is an object and body.result is a string, you can do

resultObj = JSON.parse(body.result)
resultObj[0].prediction[0].probability
2 Likes
5

@mishavee Make sure that JSON.parse works - it only seems to parse strings like

"{key: "val"...}"

and doesn’t parse object Objects.

Screen Shot 2020-09-21 at 5.15.11 PM
Screen Shot 2020-09-21 at 5.15.11 PM1254×924 37.9 KB

6

Yes that’s the point of parse(), to convert a string to an object. If its already an object there’s no need to parse it.

The example you have is misleading, the constant is called “json” but its value is an object.

1 Like
7

Lol, yeah, I just edited the editor on JSON.parse() docs.
Too bad there’s nothing that converts string object keys…

8

Can you elaborate?

9

Like:

{
"key":value,
"key2": value,
}

Into

{
key: value, 
key2: value
}
10

I assume you want the result to be evaluated as javascript? In which case they would work the same.

Otherwise, what use would it be for?