How to create instance in for loop?

Question

I fetched data from API. storing data is very slow because inside my for loop insert data. How to create its instance before for loop or in class level?

storeWoDescription(String url,String token) async {
  final response = await http.get(
    '${url}/v1.0/WoDescription',
    headers: {'Authorization': 'Bearer ${token}'},);
  final jsonResponse = json.decode(response.body);
  WoDescription model = WoDescription.fromJson(jsonResponse);
  int length = model.data.length;

  for(int i=0; i<length; i++) {
    var data = DataWoDescription(
      i: model.data[i].i,
      d: model.data[i].d,
      e: model.data[i].e,
      w: model.data[i].w,
      a: model.data[i].a,
      r: model.data[i].r,
      t: model.data[i].t,
      du: model.data[i].du,
      s: model.data[i].s,
      ra: model.data[i].ra,
      cul: model.data[i].cul,
    );
    await HelperDefCatMaster().insertWoDescription(data);
  }
}

CopsOnRoad · Accepted Answer · 2019-04-11 12:47:35Z

1

This should be a better way to instantiate your database helper.

var helper;

void main() async {
  helper = await HelperDefCatMaster(); // instantiate it just once and use it everywhere. 
}

storeWoDescription(String url, String token) async {

  final response = await http.get(
    '${url}/v1.0/WoDescription',
    headers: {'Authorization': 'Bearer ${token}'},
  );
  final jsonResponse = json.decode(response.body);
  WoDescription model = WoDescription.fromJson(jsonResponse);
  int length = model.data.length;

  for (int i = 0; i < length; i++) {
    var data = DataWoDescription(
      i: model.data[i].i,
      d: model.data[i].d,
      e: model.data[i].e,
      w: model.data[i].w,
      a: model.data[i].a,
      r: model.data[i].r,
      t: model.data[i].t,
      du: model.data[i].du,
      s: model.data[i].s,
      ra: model.data[i].ra,
      cul: model.data[i].cul,
    );
    await helper.insertWoDescription(data);
  }
}

answered Apr 11, 2019 at 12:47

CopsOnRoad

271k97 gold badges702 silver badges471 bronze badges

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

7 Comments

user11065582 Over a year ago

I added helper in my main method, but when using await helper.insertWoDescription(data); in function helper is null

user11065582 Over a year ago

after click button i called function like this: await HelperDefCatMaster().deleteWoDescription(); await storeWoDescription(_url,tokens); Is it correct way?

user11065582 Over a year ago

still slow. why is that

CopsOnRoad Over a year ago

First, the helper should not be null for sure. I don't know how you did that and did you miss something. Second, the solution I posted is a good practice of initialising database, so don't use your 2nd comment. Don't instantiate it in for loop, don't use HelperDefCatMaster() everywhere. It should be just one time call.

user11065582 Over a year ago

where do I call this function? storeWoDescription()

|

Collectives™ on Stack Overflow

How to create instance in for loop?

1 Answer 1

7 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Related