Query a single document from Firestore in Flutter (cloud_firestore Plugin)

Question

Edit: This Question is outdated, and I am sure, new documentation and more recent answers are available as of now.

I want to retrieve data of only a single document via its ID. My approach with example data of:

TESTID1 {
     'name': 'example', 
     'data': 'sample data',
}

was something like this:

Firestore.instance.document('TESTID1').get() => then(function(document) {
    print(document('name'));
}

but that does not seem to be correct syntax.

I was not able to find any detailed documentation on querying firestore within flutter (dart) since the firebase documentation only addresses Native WEB, iOS, Android etc. but not Flutter. The documentation of cloud_firestore is also way too short. There is only one example that shows how to query multiple documents into a stream which is not what i want to do.

Related issue on missing documentation: https://github.com/flutter/flutter/issues/14324

It can't be that hard to get data from a single document.

UPDATE:

Firestore.instance.collection('COLLECTION').document('ID')
.get().then((DocumentSnapshot) =>
      print(DocumentSnapshot.data['key'].toString());
);

is not executed.

score 88 · Answer 1 · edited Jun 14 '20 at 04:27

88

but that does not seem to be correct syntax.

It is not the correct syntax because you are missing a collection() call. You cannot call document() directly on your Firestore.instance. To solve this, you should use something like this:

var document = await Firestore.instance.collection('COLLECTION_NAME').document('TESTID1');
document.get() => then(function(document) {
    print(document("name"));
});

Or in more simpler way:

var document = await Firestore.instance.document('COLLECTION_NAME/TESTID1');
document.get() => then(function(document) {
    print(document("name"));
});

If you want to get data in realtime, please use the following code:

Widget build(BuildContext context) {
  return new StreamBuilder(
      stream: Firestore.instance.collection('COLLECTION_NAME').document('TESTID1').snapshots(),
      builder: (context, snapshot) {
        if (!snapshot.hasData) {
          return new Text("Loading");
        }
        var userDocument = snapshot.data;
        return new Text(userDocument["name"]);
      }
  );
}

It will help you set also the name to a text view.

edited Jun 14 '20 at 04:27

Harsh J

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answered Nov 28 '18 at 10:52

Alex Mamo

130,605
17
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2

The error you pointed out is true but is not the main problem. According to AndroidStudio: `the getter for DocumentReference is not defined`. So `document().get()` is invalid as well. I find there is a lack of information on the basic syntax of these queries. I have even read the [specification](https://pub.dartlang.org/documentation/firebase_firestore) – blandaadrian Nov 28 '18 at 12:26
7

You should also use `await`. Please see my updated answer. Does it work now? – Alex Mamo Nov 28 '18 at 12:38
I did vote +1, but it will only appear publicly when i earn enough reputation.. **Is there any documentation or resource on this, you can recommend?** – blandaadrian Nov 28 '18 at 13:31
1

Regarding Firebase, official docs. Regarding Firebase and Flutter I don't know. – Alex Mamo Nov 28 '18 at 13:33
1

I tried the realtime stream and I get this error `The argument type 'Stream' can't be assigned to the parameter type 'Stream'.`. Any idea ? – Théo Champion Feb 06 '19 at 02:07
@ThéoChampion Please post another question for that problem with its own [MCVE](https://stackoverflow.com/help/mcve) so me and other Firebase developers can help you. – Alex Mamo Feb 06 '19 at 08:46
there are some typos in the code arent they? document('name') should be document['name'] as far as i understand how documents work with firestore – Logemann Oct 01 '19 at 18:52
if I try to pass `userDocument` to a new page as an argument I cannot do `userDocument["name"]` on the second page. I get an error because `name` doesn't exist (but it's `Instance of 'DocumentSnapshot'`) – Dani Nov 28 '19 at 11:22
@Dani Without seeing your code, I cannot be much of a help. So please post another fresh question, so I and other Firebase developers can help you. – Alex Mamo Nov 28 '19 at 11:33
It's exactly the same as the code above van sending the params instead: `var userDocument = snapshot.data; Navigator.of(context).pushNamed( '/my-set', arguments: userDocument );` – Dani Nov 28 '19 at 11:46
3

got it. Passing now `userDocument.dat`, which is the actual map (https://stackoverflow.com/questions/56721694/convert-firestore-documentsnapshot-to-map-in-flutter) – Dani Nov 28 '19 at 12:16
Thank you @AlexMamo , you answer is helpful .. Thanks a lot – Sana'a Al-ahdal Feb 04 '20 at 11:13
@AlexMamo for me I am getting this question issue with Builder. can you look into my gist. I have attached code output. and printed document. https://gist.github.com/surapuramakhil/5dbbc060c92557c18ecab6e2dc9b9cbd – Akhil Surapuram May 24 '20 at 22:35
@AkhilSurapuram You should post a new question using its own [MCVE](https://stackoverflow.com/help/mcve), so I and other Firebase developers can help you. – Alex Mamo May 25 '20 at 08:56
I believe "Firestore.instance..." has been deprecated in favor of "FirebaseFirestore.instance..." per documentation at https://firebase.flutter.dev/docs/migration/#firestore – Mark Gavagan Mar 03 '21 at 20:02

CopsOnRoad · Accepted Answer · 2021-06-06T16:11:44.333

Null safe code (Recommended)

You can either query the document in a function (for example on press of a button) or inside a widget (like a FutureBuilder).

In a method: (one time listen)

var collection = FirebaseFirestore.instance.collection('users');
var docSnapshot = await collection.doc('doc_id').get();
if (docSnapshot.exists) {
  Map<String, dynamic>? data = docSnapshot.data();
  var value = data?['some_field']; // <-- The value you want to retrieve. 
  // Call setState if needed.
}

In a FutureBuilder (one time listen)

FutureBuilder<DocumentSnapshot<Map<String, dynamic>>>(
  future: collection.doc('doc_id').get(),
  builder: (_, snapshot) {
    if (snapshot.hasError) return Text ('Error = ${snapshot.error}');

    if (snapshot.hasData) {
      var data = snapshot.data!.data();
      var value = data!['some_field']; // <-- Your value
      return Text('Value = $value');
    }

    return Center(child: CircularProgressIndicator());
  },
)

In a StreamBuilder: (always listening)

StreamBuilder<DocumentSnapshot<Map<String, dynamic>>>(
  stream: collection.doc('doc_id').snapshots(),
  builder: (_, snapshot) {
    if (snapshot.hasError) return Text('Error = ${snapshot.error}');

    if (snapshot.hasData) {
      var output = snapshot.data!.data();
      var value = output!['some_field']; // <-- Your value
      return Text('Value = $value');
    }

    return Center(child: CircularProgressIndicator());
  },
)

Can we get the subcollection along with the document by any of these methods? — who-aditya-nawandar, Dec 30 '21 at 16:51

score 26 · Answer 3 · edited Oct 02 '20 at 10:07

26

If you want to use a where clause

await Firestore.instance.collection('collection_name').where(
    FieldPath.documentId,
    isEqualTo: "some_id"
).getDocuments().then((event) {
    if (event.documents.isNotEmpty) {
        Map<String, dynamic> documentData = event.documents.single.data; //if it is a single document
    }
}).catchError((e) => print("error fetching data: $e"));

edited Oct 02 '20 at 10:07

Qiniso

2,587
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answered May 03 '20 at 16:05

thilinaj

369
3
6

I was looking for this – Krishna Shetty May 11 '20 at 02:58
how to use it later to get value from the fetched document? – Harsh J Jun 13 '20 at 04:02
@Harsh Jhunjhunuwala You can use it as a Map. Eg: if you want to retrieve a field called name from the document, var name = documentData["name"]; – thilinaj Jun 14 '20 at 16:41
1

it says "A value of type 'Map Function()' can't be assigned to a variable of type 'Map" – MwBakker Dec 20 '20 at 17:59
can this be cast to custom model? – Muhammad Aiman Bin Kamal Jun 10 '21 at 05:10

score 12 · Answer 4 · edited Sep 04 '20 at 09:10

12

This is simple you can use a DOCUMENT SNAPSHOT

DocumentSnapshot variable = await Firestore.instance.collection('COLLECTION NAME').document('DOCUMENT ID').get();

You can access its data using variable.data['FEILD_NAME']

edited Sep 04 '20 at 09:10

Arghya Sadhu

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answered Sep 04 '20 at 07:14

SWAG Assassin YT

273
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6

I can't "the operator '[]' isn't defined for the type 'Map Function()'. " – MwBakker Dec 20 '20 at 18:06
To access the data you must write variable.data()['FIELD_NAME']. I had the same problem and the () was missing. – Marci Nov 07 '21 at 14:13

jo3ght · Answer 5 · 2021-01-12T10:01:22.053

6

Update FirebaseFirestore 12/2021

StreamBuilder(
          stream: FirebaseFirestore.instance
              .collection('YOUR COLLECTION NAME')
              .doc(id) //ID OF DOCUMENT
              .snapshots(),
        builder: (context, snapshot) {
        if (!snapshot.hasData) {
          return new CircularProgressIndicator();
        }
        var document = snapshot.data;
        return new Text(document["name"]);
     }
  );
}

edited Jan 12 '21 at 10:01

answered Dec 30 '20 at 04:39

jo3ght

111
1
5

How can you take out a certain piece of information using this? Lets Say my collection is books Document is Harry Potter And under that i have table with Title Author Description, how would i print the author? – s3v3ns Feb 03 '21 at 10:02
Widget _buildBookItem(BuildContext context, int index, AsyncSnapshot snapshot) { final doc = snapshot.data.docs[index]; return Text(print(doc.author)); }; – jo3ght Feb 04 '21 at 04:26

score 3 · Answer 6 · answered Jan 11 '21 at 07:11

3

This is what worked for me in 2021

      var userPhotos;
      Future<void> getPhoto(id) async {
        //query the user photo
        await FirebaseFirestore.instance.collection("users").doc(id).snapshots().listen((event) {
          setState(() {
            userPhotos = event.get("photoUrl");
            print(userPhotos);
          });
        });
      }

answered Jan 11 '21 at 07:11

Ronny K

3,641
4
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Is this a Future Query or a Stream Query? The return is a Future, but isn't the snapshots query for Stream? I'm confused. – dontknowhy Feb 04 '21 at 04:15

score 2 · Answer 7 · edited Jan 05 '22 at 17:15

Use this code when you just want to fetch a document from firestore collection , to perform some operations on it, and not to display it using some widget (updated jan 2022 )

   fetchDoc() async {

   // enter here the path , from where you want to fetch the doc
   DocumentSnapshot pathData = await FirebaseFirestore.instance
       .collection('ProfileData')
       .doc(currentUser.uid)
       .get();

   if (pathData.exists) {
     Map<String, dynamic>? fetchDoc = pathData.data() as Map<String, dynamic>?;
     
     //Now use fetchDoc?['KEY_names'], to access the data from firestore, to perform operations , for eg
     controllerName.text = fetchDoc?['userName']


     // setState(() {});  // use only if needed
   }
}

score 1 · Answer 8 · edited May 22 '21 at 03:41

Simple way :

StreamBuilder(
          stream: FirebaseFirestore.instance
              .collection('YOUR COLLECTION NAME')
              .doc(id) //ID OF DOCUMENT
              .snapshots(),
        builder: (context, snapshot) {
        if (!snapshot.hasData) {
          return new CircularProgressIndicator();
        }
        var document = snapshot.data;
        return new Text(document["name"]);
     }
  );
}

avill blbn · Answer 9 · 2022-05-29T16:54:20.000

1

        var  document = await FirebaseFirestore.instance.collection('Users').doc('CXvGTxT49NUoKi9gRt96ltvljz42').get();
        Map<String,dynamic>? value = document.data();
        print(value!['userId']);

edited May 29 '22 at 16:54

answered May 29 '22 at 12:52

avill blbn

121
1
4

Please include an explanation with your answer to help users understand how this answers the question – Freddy Mcloughlan May 31 '22 at 01:26

score 1 · Answer 10 · edited Oct 14 '22 at 07:20

1

You can get the Firestore document by following code:

future FirebaseDocument() async{

    var variable = await FirebaseFirestore.instance.collection('Collection_name').doc('Document_Id').get();
    print(variable['field_name']); 
}

edited Oct 14 '22 at 07:20

ClaudiaR

3,108
2
13
27

answered Oct 05 '22 at 10:26

Umesh Rajput

218
1
11

score -3 · Answer 11 · edited Sep 25 '21 at 08:16

-3

Use this simple code:

Firestore.instance.collection("users").document().setData({
   "name":"Majeed Ahmed"
});

edited Sep 25 '21 at 08:16

ZygD

22,092
39
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answered Sep 25 '21 at 07:23

Majeed Ahmed

9
3

Query a single document from Firestore in Flutter (cloud_firestore Plugin)

11 Answers11

Null safe code (Recommended)

Linked

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