A value of type 'Set<Row>' can't be assigned to a variable of type 'Widget-CodePudding

After running this inside my widget tree:

List<List<Widget>> widgets;
/***/
Column(
  children: [
    for (List<Widget> range in (widgets as List<List<Widget>>)) {
      Row(children: range),
    }
  ]
)

I got this error:

Error: A value of type 'Set<Row>' can't be assigned to a variable of type 'Widget'.

CodePudding user response：

Use this remove{ USED FOR THE FOR LOOP bracket

 for (List<Widget> range in (widgets as List<List<Widget>>))
        Row(children: range),

Set or map? The syntax for map literals is similar to that for set literals. Because map literals came first, {} defaults to the Map type. If you forget the type annotation on {} or the variable it’s assigned to, then Dart creates an object of type Map<dynamic, dynamicdart tour

Tip

Also we can use like this

Column(children: [
      ...widgets.map((e) {
        return Row(children: e);
      }),
      
    ]);

CodePudding user response：

That's because you try to affect something like [[...]] to column children instead of [], try something like that :

Column(children: widgets.map(element) => Row(children: element));