How to parse JSON objects with identifiers into typescript?

Question

I have a large json object that looks like this:

{
     "item1": {
         "key1": "val1",
         "key2": "val2",
         "key3": [
             "val4",
             "val5",
         ]
    },
    {
     "item2": {
         "key1": "val1",
         "key2": "val2",
         "key3": [
             "val3",
             "val4",
         ]
    }

    ... etc ...
}

I created an interface:

interface MyObj {
    key1: string;
    key2: string;
    key3: string[];
}

Then try to parse the json:

const myObj[]: {string: Myobj[]} = JSON.parse(response);

But I get the error SyntaxError: Unexpected token o in JSON at position 1. I have checked response in a json validator and it passes.

I want to parse response into an array of MyObj.

key3 is not an object, it's array right? how you are getting data in key-value pair inside array? — Rahul Sharma
– Rahul Sharma, Commented Jul 16, 2019 at 11:13
typescript can't cause runtime errors - your response is not a well formed JSON. — thedude
– thedude, Commented Jul 16, 2019 at 11:18

Jed Richards · Accepted Answer · 2019-07-16 11:21:48Z

1

Few things going wrong here, your type definition here isn't using correct TypeScript syntax

const myObj[]: {string: Myobj[]} = JSON.parse(response);
           ^^^^^^^^^^^^^^^^^^^^^
             This looks weird

Also your response object is malformed, key3 is invalid (halfway between an array and object).

Anyway, try defining the type for the response first, and then parsing:

type MyObj = {
  key1: string
  // etc ...
}

type Response = {
  [key: string]: MyObj
}

const data:Response = JSON.parse(response)

answered Jul 16, 2019 at 11:21

Jed Richards

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4 Comments

alex87 Over a year ago

Ah, I typed out the array incorrectly. I have fixed it now. I tried your suggestion but still getting the same error.

Jed Richards Over a year ago

My suggestion is incomplete, so I'm not sure what you've tried or what your error is ...

Jed Richards Over a year ago

Btw your error SyntaxError: Unexpected token o in JSON at position 1 has nothing to do with TypeScript, it sounds like your actual JSON file is malformed.

alex87 Over a year ago

The json is fine. It was static json so I just wrote a python script to format it as a TypeScript array of objects.

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