Receiving these errors in Future builder and Future List

Question

I am facing this error, even though I have written the 'if statement'.

I also tried adding an 'else statement' like else{return Text(" "); } but then it completely ignores the 'if statement' and shows only the else statement in the Output, which is a Text widget.

I am also facing this error in the file 'db_helper.dart' when writing await dbClient!.query('cart');

a tool-tip: next time try to attach code in text form instead of code screenshots. Good Luck. — Munsif Ali, Feb 07 '23 at 18:09

score 0 · Accepted Answer · answered Feb 07 '23 at 17:17

0

The solution to the first error is return something both in if and else condition like this:

if(snapshot.hasData){
   return Expanded();
 }else{
  return Text("");
 }

and for the 2nd error make the code like this:

final List<Map<String, Object?>> queryResult=await dbClient!.query("cart");

answered Feb 07 '23 at 17:17

Munsif Ali

1,839
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try this and let me know if it is solving your problem or not. – Munsif Ali Feb 07 '23 at 17:17
The second one now gives the error "_CastError (Null check operator used on a null value)" – Shahzain Ahmed Feb 07 '23 at 17:29
which part is causing the issue? – Munsif Ali Feb 07 '23 at 17:32
final List> queryResult=await dbClient!.query("cart"); this one is giving the exception "_CastError (Null check operator used on a null value)" – Shahzain Ahmed Feb 07 '23 at 17:34
Yes this is the value " var dbClient = await db; " – Shahzain Ahmed Feb 07 '23 at 17:37
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/251696/discussion-between-munsif-ali-and-shahzain-ahmed). – Munsif Ali Feb 07 '23 at 17:47

score 0 · Answer 2 · answered Feb 07 '23 at 17:18

0

The issue with your first snippet is that you return a Widget only when snapshot.hasData, to solve this after that return outside of the if case, either return a SizedBox or a CircularProgressIndicator that will show loading until the Future yilds data.

The second snippet indicates that your return type does not match with the type of queryResult, so you can change the type of queryResult to List<Map<String, Object?>> and this will most probably fix all your errors.

answered Feb 07 '23 at 17:18

esentis

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The second snippet I changed to `List>` now it gives an exception on `final List> queryResult=await dbClient!.query("cart");` the exception is `_CastError (Null check operator used on a null value)` – Shahzain Ahmed Feb 07 '23 at 17:42
That error may be because of this `dbClient!` and the bang operator (!). – esentis Feb 07 '23 at 18:00

Receiving these errors in Future builder and Future List

2 Answers2