How to find the string from string array in firestore

Question

I have a list of documents and each document has a field of a string array named "fav", it has more than 50k emails, there are almost 1000 documents and in each document's "fav" array has variable length including 50k, 20k,10, etc. I was fetching all documents

 Firestore.instance.collection("save").snapshots();

through StreamBuilder

StreamBuilder(
      stream: Firestore.instance.collection("save").snapshots();,
      builder: (context, snapshot) {
        if (!snapshot.hasData)
          return Text("Loading Data.............");
        else {
          listdata = snapshot.data.documents;

          return _buildBody(snapshot.data.documents);
        }
      },
    )

Now How I can search my required email from each document's field "fav"? I have to perform an operation after finding the required id in the array locally.

Question isn't clear, can you add more details. If you want to fetch all the items where `fav` contains `abc@gmail.com` then you can do something like `.where("fav", arrayContains: "abc@gmail.com")`. But if you have those many emails (like in thousands), better to use collections for storing emails. — Chenna Reddy, Sep 30 '19 at 07:51
Question related to that: https://stackoverflow.com/questions/51924896/firestore-flutter-array-contains — Francis Rodrigues, Dec 18 '19 at 23:32
It was fixed on Github issue. I strongly recommend you to check the Flutter Github repository before asking for help here. ;) — Francis Rodrigues, Dec 18 '19 at 23:34

score 1 · Answer 1 · answered Oct 05 '19 at 06:24

1

The question is not very clear, but for my understanding, this is what you are looking for

Firestore.instance.collection('save')
.where('fav', arrayContains: 'abc@gmail.com').snapshots()

answered Oct 05 '19 at 06:24

Viddyut Khanvilkar

295
3
11

In current version you should implement this way: `where(string, whereFilterOp, value)`. Check it out here: https://github.com/flutter/flutter/issues/20489#issuecomment-419241219 – Francis Rodrigues Dec 18 '19 at 23:37

score 0 · Answer 2 · answered Oct 05 '19 at 00:24

The question is not very clear, but for my understanding, you want to find one e-mail in the array field. This array is contained on each document, and all the documents are "streamed" in a collection of snapshots.

Contains Method: https://api.dartlang.org/stable/2.0.0/dart-core/Iterable/contains.html

bool contains (
Object element
)

Returns true if the collection contains an element equal to element.

This operation will check each element in order for being equal to element, unless it has a more efficient way to find an element equal to element.

The equality used to determine whether element is equal to an element of the iterable defaults to the Object.== of the element.

Some types of iterable may have a different equality used for its elements. For example, a Set may have a custom equality (see Set.identity) that its contains uses. Likewise the Iterable returned by a Map.keys call should use the same equality that the Map uses for keys.

Implementation

bool contains(Object element) {
  for (E e in this) {
    if (e == element) return true;
  }
  return false;
}

How to find the string from string array in firestore

2 Answers2