How to pull and use values within JSON object contained in separate JSON file using NextJS with Typescript

Question

I made a JSON file with multiple objects containing named values assigned to strings like this,

{
    "Obj1" : {
        "Val1": "Obj 1, Test Value 1",
        "Val2": "Obj 1, Test Value 2",
        "Val3": "Obj 1, Test Value 3"
    },
    "Obj2" : {
        "Val1": "Obj 2, Test Value 1",
        "Val2": "Obj 2, Test Value 2",
        "Val3": "Obj 2, Test Value 3"
    }
}

I needed to access each value in each object individually in Next JS, I tried to import and parse the data,

import data from '~/data.json';
const obj1: any = JSON.parse(data["Obj1"]); // Side Note: What type should this const be?
console.log(obj1.Val1); // Desired Output: " Obj1, Test Value 1 "

Although, when I attempted this I ran into this error, " Argument of type '{ Val1: string; }' is not assignable to parameter of type 'string'.ts(2345) "

I cannot find how to get around this error no matter what I do. Is my JSON or TS incorrect?

Alexxino · Accepted Answer · 2025-04-10 20:39:32Z

The issue is in the JSON.parse(data["Obj1"]); expression.

By doing JSON.parse(data["Obj1"]); you are actually calling JSON.parse on this object:

{
    "Val1": "Obj 1, Test Value 1",
    "Val2": "Obj 1, Test Value 2",
    "Val3": "Obj 1, Test Value 3"
}

However, JSON.parse requires a string as argument (and the string will be converted to an object). Example:

const obj = JSON.parse('{"name":"John", "age":30, "city":"New York"}');

Therefore, you can solve your problem and get the Val1 value by just doing:

import data from '~/data.json';

// In Next.js + TS, by default the `data` object should be already correctly typed as an object. 
// However, if this is not the case, you can type it manually with an interface 
// or with the object type Record<K, T> 
const obj1: Record<string, string> = data["Obj1"]; 

console.log(obj1["Val1"]); // Output: "Obj1, Test Value 1"

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