How to call async function one by one in the initState function with Flutter

Question

Assume that I would like get the data from the backend server, and I called the API by post method at the initState. I would like to call the following function one by one.

Map response = {};
Map response2 = {};

void initState() {
   callAPI_1();
   callAPI_2();
   ShowData();
}

void callAPI_1() async {
   .
   .
   .
   HttpClientResponse responseBody = await request.close();

   this.setState((){
      response = responseBody;
   });
}


void callAPI_2() async {
   .
   .
   .
   HttpClientResponse responseBody2 = await request2.close();

   this.setState((){
      response2 = responseBody2;
   });
}

void ShowData() {
   print(response);
   print(response2);
}

Expecting the order of the programming flow should be initState -> callAPI_1 -> callAPI_1 -> ShowData;

Any suggestion of how to achieve it?

Create another async function and call it from initState, something like that — Saurabh K. Sharma
– Saurabh K. Sharma, Commented Apr 12, 2021 at 7:09

Jahidul Islam · Accepted Answer · 2021-04-12 07:09:23Z

2

Try this

Map response = {};
Map response2 = {};

void initState() {
   asyncMethod();
   
}
asyncMethod() async{
await callAPI_1();
await callAPI_2();
await  ShowData();


void callAPI_1() async {
   .
   .
   .
   HttpClientResponse responseBody = await request.close();

   this.setState((){
      response = responseBody;
   });
}


void callAPI_2() async {
   .
   .
   .
   HttpClientResponse responseBody2 = await request2.close();

   this.setState((){
      response2 = responseBody2;
   });
}

void ShowData() {
   print(response);
   print(response2);
}

answered Apr 12, 2021 at 7:09

Jahidul Islam

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Comments

Sam Chan · Accepted Answer · 2021-04-12 08:13:10Z

2

You can use SchedulerBinding.instance.addPostFrameCallback

like

@override
  void initState() {
    SchedulerBinding.instance.addPostFrameCallback((_) async {
      await callAPI_1();
      await callAPI_2();
      ShowData();
    });
  }

answered Apr 12, 2021 at 8:13

Sam Chan

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