'Future<int>'实例

Question

Future<int> getCountTodo(int taskId) async {
Database db = await this.db;
List<Map<String, dynamic>> x = await db.rawQuery('SELECT COUNT (*) from $todoTable where taskId=$taskId');
// List<Map<String, dynamic>> x = await db.rawQuery('SELECT  COUNT(*),t.title FROM todo_table td, task_table t WHERE t.id=td.taskId GROUP BY taskId');
int result = Sqflite.firstIntValue(x);
print('Todo inside task: $result');
return result;
}
Text (
// '${1}'+" ITEM", 
DatabaseHelper.instance.getCountTodo(task.tasklist[index].id).toString(),
style: TextStyle(
fontSize: 14.0,
color: Colors.grey,
fontWeight: FontWeight.bold),
)

如何在文本小部件中获得计数结果。我正在获取Future的实例。

Answer 1

最好使用将来时态:

FutureBuilder(
future: DatabaseHelper.instance.getCountTodo(task.tasklist[index].id),
builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.waiting: return Text('Loading....');
default:
if (snapshot.hasError)
return Text('Error: ${snapshot.error}');
else if (snapshot.data==null)
return Text('Loading....');
else
return Text('${snapshot.data}');
}
},
)

)