Converting a JSON string into an object

Question

I have a string object which is as follows:-

[{"TradeId":123423,"TradeDate":"2017-12-11T18:30:00.000Z","Commodity":"AL","Side":"Buy","Qty":100,"Price":2000,"Location":"NY"},
{"TradeId":123428,"TradeDate":"2017-12-15T18:30:00.000Z","Commodity":"AL","Side":"Buy","Qty":100,"Price":2000,"Location":"NY"}]

I want to use this as an array on which map can be invoked. How can this be achieved.

I did JSON.parse() of this string, but I get an error stating the following:-

Unexpected token o in JSON at position 1

When I do

JSON.parse('[{"TradeId":123423,"TradeDate":"2017-12-11T18:30:00.000Z","Commodity":"AL","Side":"Buy","Qty":100,"Price":2000,"Location":"NY"},
    {"TradeId":123428,"TradeDate":"2017-12-15T18:30:00.000Z","Commodity":"AL","Side":"Buy","Qty":100,"Price":2000,"Location":"NY"}]')

note the quotes ('') , from my node terminal, it works!!!

please note that I get this string from a websocket.

My end goal is to use this string as an Array on which I can use the map operation

socket.on('getdata', (msg) => {
    console.log("getdata",msg);
    //TradesActions.loadTrades(msg)
    myStore.dispatch(TradesActions.loadTrades(JSON.parse(msg.toString())))
})

After it is dispatched above(react+redux), its used is some component as follows:-

trades.map((trade, index) => {...})

Thanks, Amar

The error indicates that the value is already an object. See for yourself: JSON.parse([{}]). — Felix Kling
– Felix Kling, Commented Jan 2, 2018 at 12:05
But get this error when I try to do trades,map(...) trades.map is not a function — Amar Dev
– Amar Dev, Commented Jan 2, 2018 at 12:07

Cerbrus · Accepted Answer · 2018-01-02 12:08:29Z

3

JSON.parse assumes that whatever you pass to it is a string.

Your data is already an object. JSON.parse will cast said object to a string, then try to parse it. Basically, something like this:

JSON.parse(obj.toString())

Casting a object to string like that returns "[object Object]"

Now guess where the "Unexpected token o in JSON at position 1" error gets its "o" from?

TL;DR: Don't use JSON.parse. Your data already is an object.

answered Jan 2, 2018 at 12:08

Cerbrus

73.3k19 gold badges137 silver badges151 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Amar Dev Over a year ago

My String is an array of objects, but I am unable to call the map function on it, typeof says that it is a string

Amar Dev · Accepted Answer · 2018-01-04 06:40:25Z

0

I was able to solve this.

The problem was not here, but in the part of the code that was getting the message from rabbitMQ using amqplib.

After getting the message I did a JSON.parse(msg.content) instead of msg.content.toString() and it resolved the issue!! Thanks a lot everyone for their time and effort.

answered Jan 4, 2018 at 6:40

Amar Dev

1,4793 gold badges21 silver badges40 bronze badges

Collectives™ on Stack Overflow

Converting a JSON string into an object

2 Answers 2

1 Comment

Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Related