I thought I read that you can query subcollections with the new Firebase Firestore, but I don't see any examples. For example I have my Firestore setup in the following way:
Dances [collection]
danceName
Songs [collection]
songName
How would I be able to query "Find all dances where songName == 'X'"
Update 2019-05-07
Today we released collection group queries, and these allow you to query across subcollections.
So, for example in the web SDK:
db.collectionGroup('Songs')
.where('songName', '==', 'X')
.get()
This would match documents in any collection where the last part of the collection path is 'Songs'.
Your original question was about finding dances where songName == 'X', and this still isn't possible directly, however, for each Song that matched you can load its parent.
Original answer
This is a feature which does not yet exist. It's called a "collection group query" and would allow you query all songs regardless of which dance contained them. This is something we intend to support but don't have a concrete timeline on when it's coming.
The alternative structure at this point is to make songs a top-level collection and make which dance the song is a part of a property of the song.
UPDATE
Now Firestore supports array-contains
Having these documents
{danceName: 'Danca name 1', songName: ['Title1','Title2']}
{danceName: 'Danca name 2', songName: ['Title3']}
do it this way
collection("Dances")
.where("songName", "array-contains", "Title1")
.get()...
#Nelson.b.austin Since firestore does not have that yet, I suggest you to have a flat structure, meaning:
Dances = {
danceName: 'Dance name 1',
songName_Title1: true,
songName_Title2: true,
songName_Title3: false
}
Having it in that way, you can get it done:
var songTitle = 'Title1';
var dances = db.collection("Dances");
var query = dances.where("songName_"+songTitle, "==", true);
I hope this helps.
UPDATE 2019
Firestore have released Collection Group Queries. See Gil's answer above or the official Collection Group Query Documentation
Previous Answer
As stated by Gil Gilbert, it seems as if collection group queries is currently in the works. In the mean time it is probably better to use root level collections and just link between these collection using the document UID's.
For those who don't already know, Jeff Delaney has some incredible guides and resources for anyone working with Firebase (and Angular) on AngularFirebase.
Firestore NoSQL Relational Data Modeling - Here he breaks down the basics of NoSQL and Firestore DB structuring
Advanced Data Modeling With Firestore by Example - These are more advanced techniques to keep in the back of your mind. A great read for those wanting to take their Firestore skills to the next level
What if you store songs as an object instead of as a collection? Each dance as, with songs as a field: type Object (not a collection)
{
danceName: "My Dance",
songs: {
"aNameOfASong": true,
"aNameOfAnotherSong": true,
}
}
then you could query for all dances with aNameOfASong:
db.collection('Dances')
.where('songs.aNameOfASong', '==', true)
.get()
.then(function(querySnapshot) {
querySnapshot.forEach(function(doc) {
console.log(doc.id, " => ", doc.data());
});
})
.catch(function(error) {
console.log("Error getting documents: ", error);
});
NEW UPDATE July 8, 2019:
db.collectionGroup('Songs')
.where('songName', isEqualTo:'X')
.get()
I have found a solution.
Please check this.
var museums = Firestore.instance.collectionGroup('Songs').where('songName', isEqualTo: "X");
museums.getDocuments().then((querySnapshot) {
setState(() {
songCounts= querySnapshot.documents.length.toString();
});
});
And then you can see Data, Rules, Indexes, Usage tabs in your cloud firestore from console.firebase.google.com.
Finally, you should set indexes in the indexes tab.
Fill in collection ID and some field value here.
Then Select the collection group option.
Enjoy it. Thanks
You can always search like this:-
this.key$ = new BehaviorSubject(null);
return this.key$.switchMap(key =>
this.angFirestore
.collection("dances").doc("danceName").collections("songs", ref =>
ref
.where("songName", "==", X)
)
.snapshotChanges()
.map(actions => {
if (actions.toString()) {
return actions.map(a => {
const data = a.payload.doc.data() as Dance;
const id = a.payload.doc.id;
return { id, ...data };
});
} else {
return false;
}
})
);
Query limitations
Cloud Firestore does not support the following types of queries:
Queries with range filters on different fields.
Single queries across multiple collections or subcollections. Each query runs against a single collection of documents. For more
information about how your data structure affects your queries, see
Choose a Data Structure.
Logical OR queries. In this case, you should create a separate query for each OR condition and merge the query results in your app.
Queries with a != clause. In this case, you should split the query into a greater-than query and a less-than query. For example, although
the query clause where("age", "!=", "30") is not supported, you can
get the same result set by combining two queries, one with the clause
where("age", "<", "30") and one with the clause where("age", ">", 30).
I'm working with Observables here and the AngularFire wrapper but here's how I managed to do that.
It's kind of crazy, I'm still learning about observables and I possibly overdid it. But it was a nice exercise.
Some explanation (not an RxJS expert):
songId$ is an observable that will emit ids
dance$ is an observable that reads that id and then gets only the first value.
it then queries the collectionGroup of all songs to find all instances of it.
Based on the instances it traverses to the parent Dances and get their ids.
Now that we have all the Dance ids we need to query them to get their data. But I wanted it to perform well so instead of querying one by one I batch them in buckets of 10 (the maximum angular will take for an in query.
We end up with N buckets and need to do N queries on firestore to get their values.
once we do the queries on firestore we still need to actually parse the data from that.
and finally we can merge all the query results to get a single array with all the Dances in it.
type Song = {id: string, name: string};
type Dance = {id: string, name: string, songs: Song[]};
const songId$: Observable<Song> = new Observable();
const dance$ = songId$.pipe(
take(1), // Only take 1 song name
switchMap( v =>
// Query across collectionGroup to get all instances.
this.db.collectionGroup('songs', ref =>
ref.where('id', '==', v.id)).get()
),
switchMap( v => {
// map the Song to the parent Dance, return the Dance ids
const obs: string[] = [];
v.docs.forEach(docRef => {
// We invoke parent twice to go from doc->collection->doc
obs.push(docRef.ref.parent.parent.id);
});
// Because we return an array here this one emit becomes N
return obs;
}),
// Firebase IN support up to 10 values so we partition the data to query the Dances
bufferCount(10),
mergeMap( v => { // query every partition in parallel
return this.db.collection('dances', ref => {
return ref.where( firebase.firestore.FieldPath.documentId(), 'in', v);
}).get();
}),
switchMap( v => {
// Almost there now just need to extract the data from the QuerySnapshots
const obs: Dance[] = [];
v.docs.forEach(docRef => {
obs.push({
...docRef.data(),
id: docRef.id
} as Dance);
});
return of(obs);
}),
// And finally we reduce the docs fetched into a single array.
reduce((acc, value) => acc.concat(value), []),
);
const parentDances = await dance$.toPromise();
I copy pasted my code and changed the variable names to yours, not sure if there are any errors, but it worked fine for me. Let me know if you find any errors or can suggest a better way to test it with maybe some mock firestore.
var songs = []
db.collection('Dances')
.where('songs.aNameOfASong', '==', true)
.get()
.then(function(querySnapshot) {
var songLength = querySnapshot.size
var i=0;
querySnapshot.forEach(function(doc) {
songs.push(doc.data())
i ++;
if(songLength===i){
console.log(songs
}
console.log(doc.id, " => ", doc.data());
});
})
.catch(function(error) {
console.log("Error getting documents: ", error);
});
It could be better to use a flat data structure.
The docs specify the pros and cons of different data structures on this page.
Specifically about the limitations of structures with sub-collections:
You can't easily delete subcollections, or perform compound queries across subcollections.
Contrasted with the purported advantages of a flat data structure:
Root-level collections offer the most flexibility and scalability, along with powerful querying within each collection.
I'm using the shopify-buy SDK to try and fetch the articles off of my Shopify store just using JavaScript on the frontend, following the "Expanding the SDK" directions here: https://shopify.github.io/js-buy-sdk/#expanding-the-sdk.
Using the code below, I am able to retrieve my articles and some of the fields that I need.
// Build a custom query using the unoptimized version of the SDK
const articlesQuery = client.graphQLClient.query((root) => {
root.addConnection('articles', {args: {first: 10}}, (article) => {
article.add('title')
article.add('handle')
article.add('url')
article.add('contentHtml')
})
})
// Call the send method with the custom query
client.graphQLClient.send(articlesQuery).then(({model, data}) => {
console.log('articles data')
console.log(data)
})
However, I really need to pull the featured image for each article as well, and unfortunately, when I add the line article.add('image') in my articlesQuery, the resulting articles data logs null. I tried building a custom productsQuery, and that has a similiar problem - I can retrieve some of the product fields, but when I try add the line product.add('images'), I just get null back from the storefront API.
Does anyone have experience building custom/expanded queries and successfully retrieving images?
Try following:
// Fetch all products in your shop
client.graphQLClient.fetchAll().then((acticles) => {
console.log(acticles);
});
And then check in console what sort of available property names your articles have. If SDK allows you get any image data, there should be for sure anything like imageSrc || imageUrl || img......
Thanks to Rebecca Friedman on the js-buy-sdk repo's github issues section for providing this working solution:
const articlesQuery = client.graphQLClient.query((root) => {
root.addConnection('articles', {args: {first: 10}}, (article) => {
article.add('title')
article.add('handle')
article.add('url')
article.add('contentHtml')
article.addField('image', {}, (image) => {
image.add('id')
image.add('originalSrc')
})
})
})
// Call the send method with the custom query
client.graphQLClient.send(articlesQuery).then(({model, data}) => {
console.log('articles data')
console.log(data) // works!
})
Because the image field is its own object, you have to add a callback function to specify the fields you need.
I'm just starting out with javascript and node.js, so this is probably basic. What I want to do is save the output from the Yummly query into a variable. Preferably an array or a list. Eventually a dictionary, but right now I just need to make headway on the basic concept and I can figure the rest out.
The module works and the data outputs to the console correctly, but I can't get it to save to any sort of variable. I have tried both push and concat in just about very location a program of this limited size format allows.
Can someone please explain or demonstrate how to save the output of the Yummly query to an array or list instead of to the console?
If possible, could you also explain why it doesn't work as it is written now? With names a global new global array and each recipe name being pushed to it in the inner loop?
P.S. I'm primarily a Python programmer trying to make the jump, so the extra information would be appreciated.
const Yummly = require('ws-yummly');
Yummly.config({
app_key: 'KEY GOES HERE',
app_id: 'ID GOES HERE'
});
const names = new Array();
Yummly.query('chicken')
.maxTotalTimeInSeconds(1400)
.maxResults(20)
.minRating(3)
.get()
.then(function(resp){
resp.matches.forEach(function(recipe){
console.log(recipe.recipeName);
names.push(recipe.recipeName);
});
});
console.log(names);
Short story you need to wait for the query to finish.
Here's a working sample.
const Yummly = require('ws-yummly');
Yummly.config({
app_key: 'KEY GOES HERE',
app_id: 'ID GOES HERE'
});
async function main () {
const resp = await Yummly.query('chicken')
.maxTotalTimeInSeconds(1400)
.maxResults(20)
.minRating(3)
.get();
const names = resp.matches.map(recipe => recipe.recipeName);
console.log(names);
}
main().catch(error => console.error(error))
Your code is equivalent too
const Yummly = require('ws-yummly');
Yummly.config({
app_key: 'KEY GOES HERE',
app_id: 'ID GOES HERE'
});
const names = new Array();
console.log(names);
Yummly.query('chicken')
.maxTotalTimeInSeconds(1400)
.maxResults(20)
.minRating(3)
.get()
.then(function(resp){
resp.matches.forEach(function(recipe){
console.log(recipe.recipeName);
names.push(recipe.recipeName);
});
});
because the .then occurs after the network request.
The fix is to use async/await.
I am using Firebase to store information for a workout application.
I user adds a workout name and then I push it to the database. I can continue pushing these but my issue is that it does not seem to be pushing as an array just an object. See the screen shots below...
As you can see in the console log picture the workouts property is an object not an array like I expect.
The code I'm using to push it:
let newWorkout = {
title: 'title',
exercises: [{
name: 'pulldownsnsn',
sets: 4
}]}
let ref = firebase.database().ref("/userProfile/"+this.userId);
ref.child("workouts").push(newWorkout);
The Firebase Database stores lists of data in a different format, to cater for the multi-user and offline aspects of modern web. The -K... are called push IDs and are the expected behavior when you call push() on a database reference.
See this blog post on how Firebase handles arrays, this blog post on the format of those keys, and the Firebase documentation on adding data to lists.
Arrays are handy, but they are a distributed database nightmare for one simple reason: index element identification is not reliable when elements get pushed or deleted. Firebase database instead uses keys for element identification:
// javascript object
['hello', 'world']
// database object
{ -PKQdFz22Yu: 'hello', -VxzzHd1Umr: 'world' }
It gets tricky when using push(), because it does not actually behaves like a normal push, but rather as a key generation followed by object modification.
Example usage
firebase.database().ref('/uri/to/list').push(
newElement,
err => console.log(err ? 'error while pushing' : 'successful push')
)
Heres an example from firebase documentation:
const admin = require('firebase-admin');
// ...
const washingtonRef = db.collection('cities').doc('DC');
// Atomically add a new region to the "regions" array field.
const unionRes = await washingtonRef.update({
regions: admin.firestore.FieldValue.arrayUnion('greater_virginia')
});
// Atomically remove a region from the "regions" array field.
const removeRes = await washingtonRef.update({
regions: admin.firestore.FieldValue.arrayRemove('east_coast')
});
More info on this firebase documentation.
In Mongoose, I can use a query populate to populate additional fields after a query. I can also populate multiple paths, such as
Person.find({})
.populate('books movie', 'title pages director')
.exec()
However, this would generate a lookup on book gathering the fields for title, pages and director - and also a lookup on movie gathering the fields for title, pages and director as well. What I want is to get title and pages from books only, and director from movie. I could do something like this:
Person.find({})
.populate('books', 'title pages')
.populate('movie', 'director')
.exec()
which gives me the expected result and queries.
But is there any way to have the behavior of the second snippet using a similar "single line" syntax like the first snippet? The reason for that, is that I want to programmatically determine the arguments for the populate function and feed it in. I cannot do that for multiple populate calls.
After looking into the sourcecode of mongoose, I solved this with:
var populateQuery = [{path:'books', select:'title pages'}, {path:'movie', select:'director'}];
Person.find({})
.populate(populateQuery)
.execPopulate()
you can also do something like below:
{path:'user',select:['key1','key2']}
You achieve that by simply passing object or array of objects to populate() method.
const query = [
{
path:'books',
select:'title pages'
},
{
path:'movie',
select:'director'
}
];
const result = await Person.find().populate(query).lean();
Consider that lean() method is optional, it just returns raw json rather than mongoose object and makes code execution a little bit faster! Don't forget to make your function (callback) async!
This is how it's done based on the Mongoose JS documentation http://mongoosejs.com/docs/populate.html
Let's say you have a BookCollection schema which contains users and books
In order to perform a query and get all the BookCollections with its related users and books you would do this
models.BookCollection
.find({})
.populate('user')
.populate('books')
.lean()
.exec(function (err, bookcollection) {
if (err) return console.error(err);
try {
mongoose.connection.close();
res.render('viewbookcollection', { content: bookcollection});
} catch (e) {
console.log("errror getting bookcollection"+e);
}
//Your Schema must include path
let createdData =Person.create(dataYouWant)
await createdData.populate([{path:'books', select:'title pages'},{path:'movie', select:'director'}])