isLoading without setState? Flutter (CircularProgressIndicator)-CodePudding

I tried

setState(() {isLoading = true})
//do something
setState(() {isLoading = false})

in the onTab(){}

but with setState the data like pdfFile and pdfController gets overridden and the app is not pushing to a new route.

Well, my question is: How to show a loading animation to user and if the loading stuff is finished, push to the screen with the downloaded data? Maybe I need something without setState? What possibilities we have?

body: StreamBuilder(
        stream: firebase.base
            .collection('xxx')
            .doc(firebase.auth.currentUser!.uid)
            .collection("xxx")
            .snapshots(),
        builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
          if (snapshot.hasData) {

            final liste = snapshot.data!.docs;
               return Column(
              children: [
                Container(
                  height: 400,
                  child: ListView.builder(
                    padding: const EdgeInsets.all(8),
                    itemCount: liste.length,
                    itemBuilder: (BuildContext context, int index) {
                      Map data = snapshot.data!.docs[index].data() as Map;
                     String fileName = data['fileName'];
                     String url = data['url'];
                      return GestureDetector(
                        onTap: () async {
                          http.Response pdfFile =
                              await http.get(Uri.parse(url));

                          final pdfController = PdfController(
                              document:
                                  PdfDocument.openData(pdfFile.bodyBytes));

                          Navigator.push(
                              context,
                              MaterialPageRoute(
                                  builder: (context) =>
                                      PdfViewScreen(pdfController, fileName)));
                        },

CodePudding user response：

You can use else expression after curly bracket. Or use only return Center(child: CircularProgressIndicator()); after if

CodePudding user response：

Perhaps the follow logic works for you:

onTap only redirects the user to PdfViewScreen. In PdfViewScreen you use a FutureBuilder to resolve http.get(Uri.parse(url)) after which the FutureBuilder will return the PDFviewer that you use. In the FutureBuilder you can then show a progressIndicator