My menu item tree looks is shown below:
menuItem
J1
-description:"Tasty milk shake!"
-img:"assets/images/milkshake.JPG"
-itemName:"Milk Shake"
-price:20
-varieties
-var1:"Chocolate"
-var2:"Vanilla"
-var3:"Strawberry"
I want to get just the item IDs (J1, J2, J3 ect.) but not all the information such as 'itemName'
final DatabaseReference _dbRef = FirebaseDatabase.instance.ref();
final items = await _dbRef.child('menuItem').get();
if (items.exists) {
String? itemID = items.value.toString();
}
items.values returns all the information for an item and items.key returns only 'menuItem'.
How can I just get the IDs only?
With the Realtime Database queries done via the Client SDKs are deep: They always return the entire subtree.
This is a key difference with Firestore for which queries are shallow: They only return documents in a particular collection or collection group and do not return subcollection data.
However, with the Realtime Database REST API you can use a query parameter named shallow, which "limits the depth of the data returned at a location". I've never used it but it seems that it will fulfill your requirement.
Another solution would to denormalise your data and maintain, in parallel to the menu items, a list of menu IDs in a specific DB node.
As Renaud explained in his answer, all read operations in the Firebase Realtime Database SDKs return complete branches of the tree, and can't be used to just read the keys.
That said, you can use just the keys from the data you read with:
final DatabaseReference _dbRef = FirebaseDatabase.instance.ref();
final items = await _dbRef.child('menuItem').get();
items.forEach((child) => {
console.log(child.key);
})
The above will still retrieve the entire menuItem branch of your database, but only show the keys under that node (so J1 from the sample you shared).
Related
I have a collection in firebase called "community" and "users". All user records have a field "joinedCommunity" (a list of all joined communities).
I'm trying to figure a code that when a community is deleted, all user records are updated to only remove the community reference from "joinedCommunity" field list.
building this in flutterflow using custom action
onTap on a button in UI, the code is included as one of the actions before community document is deleted.
Future userRecordUpdate(DocumentReference community) async {
final instance = FirebaseFirestore.instance;
final batch = instance.batch();
var collection = instance.collection('users');
batch.update(collection, {
"joinedCommunity": FieldValue.arrayRemove([community])
});
await batch.commit();
}
You're using a CollectionReference, when what you want is a DocumentReference. As per the documentation, WriteBatch.update only works on a DocumentReference.
I have a few suggestions:
Try updating the field without using a WriteBatch. Use a for loop and a regular DocumentReference.update() call.
Then, update your code to use a WriteBatch to update the field. Also, keep in mind a batch is limited to 500 operations.
Finally, consider the security implications of allowing a client to be able to update any User document. You should probably update your security rules so that a user document can only be modified by that user. This code is probably something that should run in a Firebase Cloud Function that gets triggered whenever a community document is deleted.
the following code worked -
Future userRecordUpdate(DocumentReference community) async {
final instance = FirebaseFirestore.instance;
final batch = instance.batch();
var collection = instance.collection('users');
var snapshots =
await collection.where("joinedCommunity", arrayContains:
community).get();
for (var doc in snapshots.docs) {
batch.update(doc.reference, {
"joinedCommunity": FieldValue.arrayRemove([community])
});
}
await batch.commit();
}
On the explore page, I get() the entire users collection to create a user list and search results. Inside each of those user documents is a collection posts that I also need to get to create a GridView of each post. I want to reuse that users collection QuerySnapshot instead of fetching each posts collection again to save money. Is this possible?
Here is my current function:
void fetchUsers() async {
final userRef = FirebaseFirestore.instance.collection('users');
final QuerySnapshot result = await userRef.get();
final docs = result.docs.asMap();
docs.forEach((index, value) {
final profile =
ProfileObject.fromJson(value.data() as Map<String, dynamic>);
usersList.add(UserSearchResult(profile, value.id));
/// Below is the code for getting the posts, not working, need ideas
final QuerySnapshot postsResult = value.get('posts');
final posts = postsResult.docs.asMap();
posts.forEach((index, value) {
final post = Post.fromJson(value.data() as Map<String, dynamic>);
postsList.add(post);
});
});
print(usersList);
print(postsList);
}
Here is the structure of my Firestore:
users
uid (doc)
posts (collection)
info (fields)
uid (doc)
posts (collection)
info (fields)
It is not possible to call a collection to get all sub-collections. You should restructure your database to include sub-collection data in document itself. You can use a map or list for that. But remember, calling everything in one go may end up in slow performance and you might end up losing your customers. So the best way is to include the info in every posts' documents. That way, you won't loss your money and user won't feel lag in performance.
It is not possible. You fetch a document, then fetch the (sub)collection under it.
Subcollection data are not included in the initial document snapshots because Firestore queries are shallow. There shouldn't be any cost savings that you can do there?
See the similar Q&A:
Firestore: Get subcollection of document found with where
/Countries/Lebanon/Governorates/Mount Lebanon/Districts/Chouf/Cities/Wadi al-Zayneh/Data/Products/Main Categories/Restaurants & Bakeries/Sub Categories/Snack/Sub Categories/Abo Arab Cafe
So as you can see, this is a snippet from my current Firestore structure. So many deeply nested collections. The issue is, I want to keep going deeper as long as a collection called 'Sub Categories' is found which in that case I would render them in the UI. And when eventually I reach a level where 'Sub Categories' is not found, I will render a different UI and show the actual products (The last document "Abo Arab Cafe" contains all the products as maps). The pattern of how many Sub Categories there are is unexpectable and can be modified by the end user.
How can I keep checking for Sub Categories? How to manage my queries in a way that they are dynamically generated at each level at the client-side?
I use Flutter. Here is my current queries structure:
import 'package:cloud_firestore/cloud_firestore.dart';
class FirebaseServices {
final FirebaseFirestore _db = FirebaseFirestore.instance;
CollectionReference mainCategoryCollectionReference() {
CollectionReference mainCategoryCollectionReference = _db.collection(
'/Countries/Lebanon/Governorates/Mount Lebanon/Districts/Chouf/Cities/Wadi al-Zayneh/Data/Products/Main Categories');
return mainCategoryCollectionReference;
}
CollectionReference subCategoryCollectionReference(
String parentSelectedCategory) {
CollectionReference mainCategoryCollectionReference = _db.collection(
'/Countries/Lebanon/Governorates/Mount Lebanon/Districts/Chouf/Cities/Wadi al-Zayneh/Data/Products/Main Categories/$parentSelectedCategory/Sub Categories');
return mainCategoryCollectionReference;
}
bool checkIfSubCategoriesExist(CollectionReference collectionReference) {
bool subCategoriesExist;
collectionReference.get().then((value) => {
subCategoriesExist = value.docs.isNotEmpty,
print('SubCategoriesExist: $subCategoriesExist')
});
return subCategoriesExist;
}
}
This works only if I know for certain how many levels of deepness there are, but since this can be modified by the user, it won't work.
Sorry for the very long question I had no idea how to explain it properly and clearly. Thank you in advance!
The structure is all wrong, there is no point in the structure being this deeply nested. The structure of the database needs to match what has to appear in the UI.
Assuming this is a worldwide application since you are using countries then you have to do the following:
Collection
Document
Fields
Countries
Random ID
countryName - arrayOfDistrict- arrayOfGovernorates
3 Fields under each document id, containing information about the country.
Then regarding Resturants:
Collection
Document
Fields
SubCollection
subCollectionId
Fields
Resturant
Random ID
resturant_name- resturant_location - info_about_resturant
Menu
randomId
dish_name - price -...
The problem with your db structure is that it is very nested instead of making a flat structure and that right now you are harcoding the whole path.
Using the above structure, you can create a dropdown with list of countries if the user chooses Lebanon, then you get the districts and the governorates. Then you can do a call to get the resturants that are inside each district, since in the documents inside Resturant collection you can get location of each resturant and name.
After that on click of each resturant, you will get the data inside the subcollection that will contain the full menu.
I think I found the solution with the help of a friend!
Since the checkIfSubCategoriesExist function is always checking on the very last reached level(using the collectionReference argument) whether Sub Categories exists or not, he suggested that in case it does exist, I can append to its argument collectionReference the new "Sub Categories" String to the path as a variable! This way I can query on it and voila!
I'm trying to fetch a list of documents (documentID) from Firestore and add it to a List. I have seen some options but since I am a little new in this area, perhaps the obvious is becoming difficult for me. And I don't know exactly where in the code those lines should go, for example in an initState.
This is one of the options that I have chosen, but it only generates instances and not the name of the documents as such.
final QuerySnapshot result =
await Firestore.instance.collection('submits').getDocuments();
final List<DocumentSnapshot> documents = result.documents;
List<String> myListString = []; // My list I want to create.
myListString.add(documents); // The way I try to add the doc list to my String list.
Example the data base. I want to get a list of the document ID to a List-String-
enter image description here
And if possible, you could tell me if there is an analogous way to apply it to obtain a List but in the case of two or more collections.
It seems like what you want is a list of the document ids, right?
If so, this should work:
final QuerySnapshot result =
await Firestore.instance.collection('submits').getDocuments();
final List<DocumentSnapshot> documents = result.documents;
List<String> myListString = []; // My list I want to create.
documents.forEach((snapshot) {
myListString.add(snapshot.documentID)
});
I am creating an iOS application to help users who collect figurines keep track of their figurines and see realtime price information.
I have two collections:
The "master" collection
This is essentially a catalog of thousands of figurines users can select to add to their collection. It has information about each item, such as Artist, Original Price, Barcode, Year, Comments, etc.
The "user" collection
This contains documents for each user. Each of these "user" documents has a sub-collection with documents for each figurine they have added to their collection.
Currently, if a user wants to add a new item to their personal collection, they go to the "master" collection UITableView and swipe to add an item. The item document is basically copied from the "master" collection and a new document in the user sub-collection is created. They can then go to a UITableView that displays the items they have added. They have the option to add their own information about the item, such as comments, date bought, date sold, price bought, etc.
My question: How can I sync information between the document in the user collection/sub-collection and the document in the main collection? Say the "Market Price" for an item has gone up, so I update the main collection database. How can I get this price change to display in all users' collections?
I assume by using Cloud Functions, but I wanted to post here in case there was an easier method.
This is definitely a good use for Cloud Functions. Create an onUpdate trigger for your /users{uid}/figurines/{figurineId} collection and then use that to copy the updated data to the master.
You can either copy specific fields or you can check for differences by examining event.data.data() and event.data.previous.data()
const admin = require('firebase-admin');
const functions = require('firebase-functions');
admin.initializeApp(functions.config().firebase);
const db = admin.firestore();
exports.updateMaster = functions.firestore
.document('users/{uid}/figurines/{figurineId}')
.onUpdate(event => {
var newData = event.data.data();
var oldData = event.data.previous.data();
var updateData = {};
if (oldData.price != newData.price) {updateData.price = newData.price}
// Add any more changes that you may want to compare / update below...
// Then...
return db
.collection('master')
.doc(event.params.figurineId)
.update(updateData).then(response => {
console.log('We updated figurine', event.params.figurineId);
}).catch(err => {
console.error('There was an error', err);
});
});