Flutter error : An expression whose value can be 'null' must be null-checked before it can be dereferenced

Question

I want to Open Drawer in flutter and used Scaffold key and was working before but after the flutter upgrade, I am getting this error:

An expression whose value can be 'null' must be null-checked before it can be dereferenced.
Try checking that the value isn't 'null' before dereferencing it.

My code goes like this:

I declared a Global Scaffold key GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey(); then called it by flat button

FlatButton.icon(
                     label: Text("filter",style: style2.copyWith(color:Colors.lightGreenAccent[400],fontWeight: FontWeight.bold),),
                     onPressed: (){
                      _scaffoldKey.currentState.openEndDrawer();
                     },
),

Paresh Mayani · Accepted Answer · 2021-02-03 07:13:34Z

4

An expression whose value can be 'null' must be null-checked before it can be dereferenced. Try checking that the value isn't 'null' before dereferencing it.

=> The statement is saying when using a nullable variable or expression, be sure to handle null values. For example, you can use an if statement, the ?? operator, or the ?. operator to handle possible null values.

Refer the official documentation for more details: https://dart.dev/null-safety#using-variables-and-expressions

And so you should use ?. operator for handling the possible null value of the currentState:

_scaffoldKey.currentState?.openEndDrawer();

answered Feb 3, 2021 at 7:13

Paresh Mayani

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Akif · Accepted Answer · 2021-02-03 07:02:16Z

2

You can change your method like this:

_scaffoldKey.currentState?.openEndDrawer();

answered Feb 3, 2021 at 7:02

Akif

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