Cloud Firestore deep get with subcollection

问题:

Let's say we have a root collection named 'todos'.

Every document in this collection has:

1. title: String
2. subcollection named todo_items

Every document in the subcollection todo_items has

1. title: String
2. completed: Boolean

I know that querying in Cloud Firestore is shallow by default, which is great, but is there a way to query the todos and get results that include the subcollection todo_items automatically?

In other words, how do I make the following query include the todo_items subcollection?

db.collection('todos').onSnapshot((snapshot) => {   snapshot.docChanges.forEach((change) => {     // ...   }); }); 

回答1:

This type of query isn't supported, although it is something we may consider in the future.

回答2:

you could try something like this

db.collection('coll').doc('doc').collection('subcoll').doc('subdoc')  

Hope this helps !

回答3:

I have faced the same issue but with IOS, any way if i get your question and if you use auto-ID for to-do collection document its will be easy if your store the document ID as afield with the title field in my case :

let ref = self.db.collection("collectionName").document()  let data  = ["docID": ref.documentID,"title" :"some title"] 

So when you retrieve lets say an array of to-do's and when click on any item you can navigate so easy by the path

ref = db.collection("docID/\(todo_items)") 

I wish i could give you the exact code but i'm not familiar with Javascript

回答4:

If anyone is still interested in knowing how to do deep query in firestore, here's a version of cloud function getAllTodos that I've come up with, that returns all the 'todos' which has 'todo_items' subcollection.

exports.getAllTodos = function (req, res) {     getTodos().         then((todos) => {             console.log("All Todos " + todos) // All Todos with its todo_items sub collection.             return res.json(todos);         })         .catch((err) => {             console.log('Error getting documents', err);             return res.status(500).json({ message: "Error getting the all Todos" + err });         }); }  function getTodos(){     var todosRef = db.collection('todos');      return todosRef.get()         .then((snapshot) => {             let todos = [];             return Promise.all(                 snapshot.docs.map(doc => {                           let todo = {};                                         todo.id = doc.id;                         todo.todo = doc.data(); // will have 'todo.title'                         var todoItemsPromise = getTodoItemsById(todo.id);                         return todoItemsPromise.then((todoItems) => {                                                     todo.todo_items = todoItems;                                 todos.push(todo);                                          return todos;                                               })                  })             )             .then(todos => {                 return todos.length > 0 ? todos[todos.length - 1] : [];             })          }) }   function getTodoItemsById(id){     var todoItemsRef = db.collection('todos').doc(id).collection('todo_items');     let todo_items = [];     return todoItemsRef.get()         .then(snapshot => {             snapshot.forEach(item => {                 let todo_item = {};                 todo_item.id = item.id;                 todo_item.todo_item = item.data(); // will have 'todo_item.title' and 'todo_item.completed'                              todo_items.push(todo_item);             })             return todo_items;         }) } 

文章来源: Cloud Firestore deep get with subcollection