The return type 'Set<Text>' isn't a 'Widget', as required by the clos-CodePudding

The inner map function is causing the error in the title and I don't know how I can fix this. I want to make a calculation in the inner map function before returning the Widget.

 var rowOnee = Column(children: [
      ...stampRows.map((i) => Row(
            children: [
              ...[0,1,2,3,4].map((i) => {
                return Text("hi");
              })
            ],
          ))
    ]);

CodePudding user response：

There are a few ways to fix it. One way is to remove the arrow:

 var rowOnee = Column(children: [
      ...stampRows.map((i) => Row(
            children: [
              ...[0,1,2,3,4].map((i) {
                return Text("hi");
              })
            ],
          ))
    ]);

Or you could remove the curly brackets and return statement:

var rowOnee = Column(children: [
     ...stampRows.map((i) => Row(
           children: [
             ...[0,1,2,3,4].map((i) => Text("hi"))
           ],
         ))
   ]);

CodePudding user response：

This is not the correct way to write an anonymous function in dart:

(i) => {
  return Text("hi");
}

You can either do:

(i) {
  return Text("hi");
}

(i) => Text("hi"),

Note that the anonymous function has either => for single expression anonymous functions or {} for multiline anonymous functions, but not both.

When you have both, the {} is interpreted instead as a set literal.

That said, you really should use collection-for instead of combining ... and .map. I suggest rewriting your code as the following:

var rowOnee = Column(children: [
  for (var i in stampRows)
    Row(children: [
      for (var i in [0, 1, 2, 3, 4]) Text("hi")
    ]),
]);