Accessing sub-collection in snapshot.data

Question

Hello, I build one ListView with a FutureBuilder. But I need to access a sub-collection, then a document and get a field from the document. But returns null, how do I do that?

For example: To get the field test of the document, I do: snapshot.data[index].data["test"]

but to enter the sub_collection, Document and obtain the field of test, I can’t do it the normal way (which is used by Hasura)

snapshot.data[index].data["sub_collection"]["document"]["test"]

My code so far

getEstablishments:

    Future getEstabelecimentos() async {

  var firestore = Firestore.instance;

  QuerySnapshot dados =
      await firestore.collection("estabelecimentos").getDocuments();

  return dados.documents;
}

Futurebuilder:

Container(
            child: FutureBuilder(
                future: getEstabelecimentos(),
                builder: (_, snapshot) {
                  if (snapshot.connectionState == ConnectionState.waiting) {
                    return new Column(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        SizedBox(height: 15),
                        Center(
                          child: CircularProgressIndicator(
                            valueColor: new AlwaysStoppedAnimation<Color>(
                                Colors.blue),
                          ),
                        )
                      ],
                    );
                  } else {
                    return Container(
                        decoration: BoxDecoration(
                          borderRadius: const BorderRadius.only(
                              topLeft: Radius.circular(30),
                              topRight: Radius.circular(30)),
                          color: Colors.white,
                        ),
                        child: Column(
                          children: <Widget>[
                            Container(
                              color: Colors.white,
                              child: ListView.builder(
                                  shrinkWrap: true,
                                  physics: NeverScrollableScrollPhysics(),
                                  itemCount: snapshot.data.length,
                                  itemBuilder: (_, index) {
                                    print(snapshot.data[index].data["name"]);
                                    print(snapshot.data[index].data["category"]);
                                    return GestureDetector(
                                      child: makeItem(nome: snapshot.data[index], categoria: snapshot.data[index].data["categoria"], checkins: snapshot.data[index].data["sub_colecao"]["documento"]['teste']),
                                      onTap: () => {},
                                    );
                                  }),
                            ),
                          ],
                        ));
                  }
                }),
          )