如何在Firebase中循环遍历数组?
问题描述：
我正在尝试从Firebase获取数据.但是我对此有点挣扎，这就是现在的样子
Im trying to get data from firebase. But im a bit struggling with that heres how it looks now
getusers() async {
var firestore = FirebaseFirestore.instance;
List listOfIds = [];
QuerySnapshot qn= await firestore
.collection('videos')
.get()
.then((QuerySnapshot querySnapshot) {
querySnapshot.docs.forEach((doc) {
setState(() {
});
});
});
if (!mounted) return;
_allResults =qn.docs;
我想要的是获取hashtasg数组字段，然后将其添加到_allresults中的qn.doc数据中.但是我该怎么做呢?这是我的火力基地，因此您可以看到它的外观
What I want is get the hashtasg array field and then add it to the qn.doc data in _allresults . But how can I do that ? Heres my firebase so you can see how it looks
最后一步，我想遍历how叫主题标签数组
And last step I wanna loop over the howle hashtag array
这是我的小部件
class Openalldocs extends StatefulWidget {
final TextEditingController searchinginput;
static const route = '/openalldocs';
const Openalldocs({Key key, this.searchinginput}) : super(key: key);
@override
_OpenalldocsState createState() => _OpenalldocsState();
}
class _OpenalldocsState extends State<Openalldocs> {
List _allResults = [];
List _resultsList = [];
Future resultsLoaded;
bool nosuerfound = false;
String searchresult;
@override
void initState() {
super.initState();
widget.searchinginput.addListener(_onsearchChanged);
setState(() {
nosuerfound = true;
});
}
@override
void dispose() {
widget.searchinginput.removeListener(_onsearchChanged());
super.dispose();
}
@override
void didChangeDependencies() {
widget.searchinginput.text;
resultsLoaded = getusers();
super.didChangeDependencies();
}
_onsearchChanged() {
setState(() {
nosuerfound = false;
});
searchResults();
}
searchResults() {
var showResults = [];
if (widget.searchinginput.text != "") {
for (var tripsnapshot in _allResults) {
var title = DatbaseService.instance
.videosfromsnapshot(tripsnapshot)
.hashtag1
.toLowerCase();
var title2 = DatbaseService.instance
.videosfromsnapshot(tripsnapshot)
.hashtag2
.toLowerCase();
var title3 = DatbaseService.instance
.videosfromsnapshot(tripsnapshot)
.hashtag3
.toLowerCase();
if (title.contains(widget.searchinginput.text.toLowerCase()) ||
title2.contains(widget.searchinginput.text.toLowerCase()) ||
title3.contains(widget.searchinginput.text.toLowerCase())) {
setState(() {
nosuerfound = true;
});
showResults.add(tripsnapshot);
}
}
} else {
setState(() {
nosuerfound = true;
});
showResults = List.from(_allResults);
}
setState(() {
_resultsList = showResults;
});
}
getusers() async {
var firestore = FirebaseFirestore.instance;
List listOfIds = [];
QuerySnapshot qn= await firestore
.collection('videos')
.get()
.then((QuerySnapshot querySnapshot) {
querySnapshot.docs.forEach((doc) {
setState(() {
_allResults.add(doc.data()["hashtag1"]);
});
});
});
if (!mounted) return;
searchResults();
return "Complete";
}
@override
Widget build(BuildContext context) {
final user = Provider.of<Userforid>(context);
if (nosuerfound == true) {
return ListView.builder(
itemCount: _resultsList.length,
itemBuilder: (BuildContext context, int index) {
return Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
// the AMOUNT is how many hashtags you want to show
for (var i = 0; i < _resultsList.length; i += 1) ...[
// the SizedBox will only exist between the elements in the list
// as before
if (i != 0) SizedBox(height: 6),
// create a builder to allow declaring a variable
Builder(
builder: (context) {
// declare the hashtag variable
final hashtag = 'hashtag${i + 1}';
return InkWell(
onTap: () {
// do something with the hashtag stored in the variable
// this will make it relative to the element in the list
},
child: Column(
children: <Widget>[
// why is there a Column inside another with only one child?
// I would recommend to remove it
Column(
children: [
HighlightedMatchesText(
searchString: widget.searchinginput.text,
// notice how I am using the hashtag variable here
// instead of a constant? ('hashtag1'), by the way
// the for loop will make the hashtag start at 0
// you can change it by increment in the declaration
// `final hashtag = 'hashtag${i+1}'`, if you want
// the existing behavior
content: _resultsList[index][hashtag],
),
],
),
// what is this? if it is to add more space between the items
// in the list, I recommend removing it from here, and add it
// to the first `SizedBox` in the for loop
// in case you do that, the Column that this widget belong
// would also only now contain one widget, so, there is no
// need to have it
SizedBox(height: 3),
],
答
您正确使用了Firestore方法， querySnapshot.docs 是该集合中您正在循环浏览的所有文档的数组使用 forEach -您只需要在 doc.data()上添加更多逻辑.
You are using the Firestore methods correctly, the querySnapshot.docs is an array of all documents in that collection that you are looping through with forEach - You only require further logic on the doc.data().
在这种情况下:将所有"hashtag1" 推入结果
in this case: push all "hashtag1" to the results
.then((QuerySnapshot querySnapshot) {
querySnapshot.docs.forEach((doc) {
setState(() {
_allResults.add(doc.data()["hashtag1"]);
});
});
更新建议的代码块
Future<String> getusers() async {
var firestore = FirebaseFirestore.instance;
List listOfIds = [];
QuerySnapshot qn= await firestore
.collection('videos')
.get();
for (var doc in qn.docs) {
setState(() {
_allResults.add(doc.data()["hashtag1"]);
});
}
});
});
if (!mounted) return "Error loading";
searchResults();
return "Complete";
}