TypeScript: Change type of element in JSON object

Question

I have a JSON object coming from a Firebase (Firestore) query.

let json = [{
  "historical_data": {
    "created_by": "HKyUyCuVj0g12htOsAPmGCcffBq2",
    "created_at": {
      "seconds": 1606403054,
      "nanoseconds": 416000000
    }
  }
}];

I need to update the created_at value to a Firestore server timestamp.

Therefore I would iterate and update the respective field like this:

for (var i in json) {
  var item = json[i];
  item.historical_data.created_at = firebase.firestore.FieldValue.serverTimestamp();
}

Although VS Code is giving me the following error message:

Type 'FieldValue' is missing the following properties from type '{ seconds: number; nanoseconds: number; }': "seconds", "nanoseconds"

I understand the error and why it's happening, so is there any way to update the JSON and change or cast the type of created_at to another one?

Zou Jeff · Accepted Answer · 2021-02-02 09:36:17Z

1

You can directly cast the return type of serverTimestamp with the as keyword in typescript:

interface CreateAt {
    seconds: number;
    nanoseconds: number;
}

for (var i in json) {
  var item = json[i];
  item.historical_data.created_at = 
    firebase.firestore.FieldValue.serverTimestamp() as CreateAt;
}

answered Feb 2, 2021 at 9:36

Zou Jeff

9331 gold badge9 silver badges16 bronze badges

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

Collectives™ on Stack Overflow

TypeScript: Change type of element in JSON object

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related