本文介绍了如何将Firestore文档列表绑定到Flutter中的下拉菜单?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我在下拉菜单和Firestore方面遇到问题,如何将从Firestore检索到的文档列表绑定到DropdownButton?当前,我遇到此错误:
I'm having a problem regarding dropdown menus and firestore, how can I bind a list of documents retrieved from firestore to a DropdownButton? Currently I'm having this error:
The argument type '(Map<dynamic, dynamic>) → DropdownMenuItem<String>' can't be assigned to the parameter type '(DocumentSnapshot) → dynamic'.
我的小部件中的代码.dart:
Code from my widget .dart:
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
class MessageList extends StatelessWidget {
MessageList({this.firestore});
final Firestore firestore;
var _mySelection;
@override
Widget build(BuildContext context) {
return StreamBuilder<QuerySnapshot>(
stream: firestore.collection('preciso-modelos').snapshots(),
builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (!snapshot.hasData) return const Text('Loading...');
return new DropdownButton<String>(
isDense: true,
hint: new Text("Select"),
value: _mySelection,
onChanged: (String newValue) {
print (_mySelection);
},
items: snapshot.data.documents.map((Map map) {
return new DropdownMenuItem<String>(
value: map["id"].toString(),
child: new Text(
map["name"],
),
);
}).toList(),
);},
);
}
}
谢谢!
推荐答案
new StreamBuilder<QuerySnapshot>(
stream: Firestore.instance.collection('categories').snapshots(),
builder: (context, snapshot){
if (!snapshot.hasData) return const Center(
child: const CupertinoActivityIndicator(),
);
var length = snapshot.data.documents.length;
DocumentSnapshot ds = snapshot.data.documents[length - 1];
_queryCat = snapshot.data.documents;
return new Container(
padding: EdgeInsets.only(bottom: 16.0),
width: screenSize.width*0.9,
child: new Row(
children: <Widget>[
new Expanded(
flex: 2,
child: new Container(
padding: EdgeInsets.fromLTRB(12.0,10.0,10.0,10.0),
child: new Text("Category",style: textStyleBlueBold,),
)
),
new Expanded(
flex: 4,
child:new InputDecorator(
decoration: const InputDecoration(
//labelText: 'Activity',
hintText: 'Choose an category',
hintStyle: TextStyle(
color: primaryColor,
fontSize: 16.0,
fontFamily: "OpenSans",
fontWeight: FontWeight.normal,
),
),
isEmpty: _category == null,
child: new DropdownButton(
value: _category,
isDense: true,
onChanged: (String newValue) {
setState(() {
_category = newValue;
dropDown = false;
print(_category);
});
},
items: snapshot.data.documents.map((DocumentSnapshot document) {
return new DropdownMenuItem<String>(
value: document.data['title'],
child: new Container(
decoration: new BoxDecoration(
color: primaryColor,
borderRadius: new BorderRadius.circular(5.0)
),
height: 100.0,
padding: EdgeInsets.fromLTRB(10.0, 2.0, 10.0, 0.0),
//color: primaryColor,
child: new Text(document.data['title'],style: textStyle),
)
);
}).toList(),
),
),
),
],
),
);
}
);
这篇关于如何将Firestore文档列表绑定到Flutter中的下拉菜单?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!