CODEWITHSUNDEEP
node.jsjsontypescript
serkanz
serkanz

Reputation: 451

Import Array from JSON File into Typescript File

I have a JSON file which contains an array object as such : 

[
  {
    "VergiNo": "XXXXXXX"
  },
  {
    "VergiNo": "YYYYYY"
  },
  {
    "VergiNo": "ZZZZZZ"
  }
]

and I import this JSON file to my Typescript file 

import * as firmalar from "../firmalar.json";

const firmaPromises = firmalar.map((firma) => firma.VergiNo + "XYZ");

Above code gives no syntax error, however when I run the application and debug it, firmalar object is seen as object not an array, so it doesn't process map method.

Is there anything wrong that I'm doing here?

Upvotes: 6

Views: 6801

Answers (4)

Piran
Piran

Reputation: 7328

To import the JSON data, you should use:

import firmalar from "../firmalar.json";

This will import it without changing it, and you'll get an array.

When you did the import with * as firmalar it tries to convert the JSON into a module, which is a kind of Object. Inspecting it you'll see it has Object style accessors, so that firmalar[0] will work, but firmalar.length will not.

Upvotes: 10

serkanz
serkanz

Reputation: 451

I ended up with using require() to get JSON and cast it to my object after that like this : 

// eslint-disable-next-line @typescript-eslint/no-var-requires
const firmalar = require("./firmalar.json");

// eslint-disable-next-line @typescript-eslint/consistent-type-assertions
const firmalarArray: { VergiNo: string }[] = firmalar;

Now it works as expected. This post helped me to find the solution.

Upvotes: 2

d-h-e
d-h-e

Reputation: 2548

I would try to parse the JSON. That should return you an array.

import * as firmalar from "../firmalar.json";

const firmalarArray = JSON.parse(firmalar);
const firmaPromises = firmalarArray.map((firma) => firma.VergiNo + "XYZ");

Upvotes: 1

Roberto Zvjerković
Roberto Zvjerković

Reputation: 10137

You're importing a whole module.

You can either import only that constant:

import { yourArray } from "../firmalar.json";

Or extract the array from the module:

const firmalarArray = JSON.parse(firmalar.yourArray);

Upvotes: 1

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