How do read data from firestore and display it in my mobile app

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Flutter

I'am using flutter in making my mobile app. I wanted to display specific data from my database in firebase into my app. The problem is that when I run hasData the output says it has no data but I already have some data inputted in my collection in firestore. How do I resolve this?

StreamBuilder<QuerySnapshot>(
                  stream: FirebaseFirestore.instance
                      .collection('customers')
                      .snapshots(),
                  builder: (
                    BuildContext context,
                    AsyncSnapshot<QuerySnapshot> snapshot,
                  ) {
                    if (snapshot.hasData) {
                      var data = 'No Data';
                      return Text(data);
                    }
                    if (snapshot.connectionState == ConnectionState.waiting) {
                      var data = 'Loading';
                      return Text(data);
                    }
                    final data = snapshot.requireData;
                    return ListView.builder(
                        itemCount: data.size,
                        itemBuilder: (context, index) {
                          return Container(
                            child: Column(
                              children: [
                                detailsWidget(
                                  icon: Icons.person,
                                  field: 'Name',
                                  value: '${data.docs[index]['name']}',
                                ),
                                detailsWidget(
                                  icon: Icons.oder,
                                  field: 'Order',
                                  value: '${data.docs[index]['order']}',
                                ),
               
                              ],
                            ),
                          );
                        });
                  }),

What I have tried:

I tried using Document Snapshot but the error always says I have null value or type null is subtype of String