Flutter 如何使用列表来创建类似的小部件 白色implicit-case 和implicity-dynamic 设置为false

Question

I'm trying to be better about typing in flutter/dart. To force this, I made an analysis_options.yaml with:

 analyzer:
  strong-mode:
    implicit-casts: false
    implicit-dynamic: false

and that works great, but I have a hard time with code like the following:

Widget build(BuildContext context) {

    return Column(
      children: [...widgetList()]);
  }

  widgetList(){
     List<Map<String,dynamic>> defineWidgets = [
      {"text":"beer", "color": Colors.blue}, // <-- Missing type arguments for map literal. Try adding an explicit type like 'dynamic' or enable implicit dynamic in your analysis options.
      {"text":"wine", "color": Colors.red},
    ];
    List<Widget> finalWidgets =[];
    for(int i = 0; i < defineWidgets.length; i++ ){
      finalWidgets.add(
        Expanded(child:Container(
          child:Text(defineWidgets[i]['text']), // <-- the argument type 'dynamic' can't be assigned to the parameter type 'String'
          color:defineWidgets[i]['color']
        ))
      );
    }
    return finalWidgets;
  }

I tried using cast() to no avail. Is there a way to do this of function without setting implicit-casts and implicit-dynamic to true?

Answer 1

The error "Missing type arguments for map literal. Try adding an explicit type like 'dynamic' or enable implicit dynamic in your analysis options." seems to require you to cast <String,dynamic> on each Map entry for defineWidgets . Though the code you've provided seems to work fine on DartPad. The declaration could look something similar to.

List<Map<String,dynamic>> pricing = [
  <String, dynamic>{"name":"beer", "price": 5},
  <String, dynamic>{"name":"wine", "price": 10},
];
  
for(Map<String,dynamic> product in pricing){
  print('${product['name']} Price: ${product['price']}');
}

As for Text(defineWidgets[i]['text']) , the Widget can only handle String value. But since we're fetching a dynamic value from Map<String, dynamic> , we need to cast the value as a String for the Widget to know that value is indeed a String.

`Text(defineWidgets[i]['text'] as String)`