How to fetch data from firestore documents from a collection and store in the list

Question

I have a list of a document ids and I want to fetch the data of those documents from Firestore and display it using the FutureBuilder.

contestList = [awebnmsdfjkeeer23,324cdas4asdf, 34sdfasgadsg]
Future<void> fetchUsergameData() async {

    contestList.forEach((element) async{ 
        await Firestore.instance.collection('LiveGames').document('$element')
            .get().then((dss) {
                if(dss.exists) {
                    tempgame.add(dss.data["GameData"]);
                    temproom.add(dss.data["Room"]);
                    temptitle.add(dss.data["Title"]);
                    temp = tempgame + temproom + temptitle;
                    joinedContests.add(temp);
                }
            }).then((value) => {});
        });

        print(joinedContests);

    }
}

I have used the above function to get the data and try to store in the list, like one document data in list. But i am getting the blank list of the data. How to get the whole document and display it using the FutureBuilder in flutter

I am quite confused with the first line. Are those supposed to be strings or variables? Either way, you won't need '$element' just element. Maybe that's why you are not getting the document (wrong/uninteded id). — VLXU

Ajordat Ajordat · Accepted Answer · 2020-06-15T12:52:47

It looks like you have multiple different issues on your code:

contestList has invalid keywords. 324cdas4asdf and 34sdfasgadsg are not valid variable names as they both start with a number, which is not a valid variable name. If they are supposed to be the ids that you want to retrieve they must be enclosed by ", which will make them strings.
You are trying to access the document using '$element' as if it were a bash variable, but there are two problems there: it's not done like that and there no need to do it. element already holds the value as a string so it just has to be accessed as is.
You are calling the method then twice without doing anything the second time. This shouldn't be a concern, but it simply doesn't do anything and can me omitted.

Below you will see an edited version of your code fixing all the aforementioned mistakes.

contestList = ["awebnmsdfjkeeer23", "324cdas4asdf", "34sdfasgadsg"]
Future<void> fetchUsergameData() async {

    contestList.forEach((element) async{ 
        await Firestore.instance.collection('LiveGames').document(element)
            .get().then((dss) {
                if(dss.exists) {
                    tempgame.add(dss.data["GameData"]);
                    temproom.add(dss.data["Room"]);
                    temptitle.add(dss.data["Title"]);
                    temp = tempgame + temproom + temptitle;
                    joinedContests.add(temp);
                }
            });
        });

        print(joinedContests);

    }
}

On another note, it's unknown to us the type of tempgame, temproom and temptitle but judging by how you are accessing it you may simply want to do something like this:

tempgame = dss.data["GameData"];
temproom = dss.data["Room"];
temptitle = dss.data["Title"];
temp = tempgame + temproom + temptitle;
joinedContests.add(temp);

How to fetch data from firestore documents from a collection and store in the list

1 Answers