从firestore中where条件的子集合的所有文档中删除数据

Question

I want to write a script that delete the data from all the documents of sub collection where status == expire. I have collection name user_data and this collection contain many documents all that documents contain sub collection name My_status and this My_status contains many documents, each document contains status and if status === expire than delete that data

The database structure is like this

collection - user_data
                     document1 - Subcollection - My_status --document1- Status expire      
                                                             document2 
                                                             document3

                     document2 - Subcollection - My_status --document1 
                                                             document2--Status expire
                                                             document3

I have tried this but this does not work as I can't relate it to sub collection

// First perform the query
db.collection('user_data').where('status','==',expire).get()
.then(function(querySnapshot) {
// Once we get the results, begin a batch
    var batch = db.batch();

    querySnapshot.forEach(function(doc) {
        // For each doc, add a delete operation to the batch
        batch.delete(doc.ref);
    });

    // Commit the batch
    return.batch.commit();
}).then(function() {
  // Delete completed!
  // ...
}); 

Answer 1

Update: As of May, 2019, Cloud Firestore now supports collection group queries .

You can now query all the My_status sub-collections:

db.collectionGroup('My_status').where('','==', 'expire').get()
.then(function(querySnapshot) {

Original Answer

What you're trying to do now is known as a "collection group query", which is not currently supported. See Firestore query subcollections

If you're trying to delete all documents from the My_status sub-collections for all users, you will need to first loop over all users, and then query each of their subcollections:

db.collection('user_data').get()
.then(function(querySnapshot) {
  querySnapshot.forEach(function(userDocument) {
    userDocument.ref.collection("My_status").where('status','==','expire').get()
    .then(function(querySnapshot) {
      ...

Alternatively, you can store the data from all subcollections in a single global collection, and include the user ID as a field in there. That way you can query the single global collection to delete all expired documents.