Question 75702 in Flutter Question posted in
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How can I upload a map with nested maps in a list as values to Firestore via dart code? – Flutter

I am using the Firestore Database. And I want to add collections and data via dart code.

This is basically how my map looks:

Map map = {
  'key1': <Map>[],
  'key2': <Map>[],
  'key3': <Map>[],
}

I basically want my firebase database structure to look like:

collectionName -> key1 -> Map1 -> "nestedMapKey1":"value"
                                  "nestedMapKey2":"value"
                          
                          Map2 -> "nestedMapKey1":"value"
                          Map3 -> etc.
                  
                  key2 -> Map1
                          Map2
                          Map3

                  key3 -> Map1 
                          Map2

I tried things like that but that’s obviously not the result I want like above.

void uploadCourses(){
    for (var k in coursesMap.keys){
      for (var v in coursesMap[k]){
        FirebaseFirestore.instance.collection('courses').doc('$k').collection('$k').add(v);
      }
    }
  }

I guess what I want is this:

FirebaseFirestore.instance.collection('courses').collection('$k').add(v);

Which is not supported. Are there any other ways to do it? Or can I simply not fill a collection with a collection?

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2

Answers


  1. 0

    Firestore’s data model starts with a number of collections at the top. Then each collection has a number of documents, which in turn can each have a number of subcollections, which each can have a number of documents, etc.

    There is no way to nest subcollections directly under a collection. You will always need a document in between.

    If I don’t have a need for multiple documents, I typically create one with an easy name, such as default and nest my subcollections under that.

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  2. 0

    Just consider each key as a document and each map as attributes of your doc. Latter it is possible to add or edit the maps individually using update.

    // Create our initial doc
db.collection("users").doc("frank").set({
  name: "Frank",
  favorites: {
    food: "Pizza",
    color: "Blue",
    subject: "Recess"
  },
  age: 12
}).then(function() {
  console.log("Frank created");
});

// Update the doc without using dot notation.
// Notice the map value for favorites.
db.collection("users").doc("frank").update({
  favorites: {
    food: "Ice Cream"
  }
}).then(function() {
  console.log("Frank food updated");
});
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