Flutter - Firebase Firestore document uid does not exists-CodePudding

My db structure is like this:

domain -> user uid -> user data

if I try to add data like this:

await FirebaseFirestore.instance
      .collection(path)
      .doc(firebaseUser.uid)
      .collection(collectionName)
      .add({...});

where path is the user domain, the database shows like this:

firestore

telling me that The document does not exists, it will not appear in queries or shapshots. But if I add the same data by auto id like this:

 await FirebaseFirestore.instance
      .collection(path)
      .add({...});

it works like the second document in picture. Why is this happening?

CodePudding user response：

Look at how the documents in this collection are displayed in an italic font in the Firestore console: This means that these documents are only present as "container" of one or more sub-collection but that they are not "genuine" documents.

As a matter of fact by doing

await FirebaseFirestore.instance
      .collection(path)
      .doc(firebaseUser.uid)
      .collection(collectionName)
      .add({...});

You create a doc in the collectionName (sub)collection but not in the path collection.

On the other hand, with

await FirebaseFirestore.instance
      .collection(path)
      .add({...});

you do create a doc in the path collection.

So if you need to have a document in the path collection AND in the collectionName (sub)collection you need to create these two documents and not only the "child" one.

DETAILED EXPLANATIONS:

Let's take the example of a doc1 document under the col1 collection

col1/doc1/

and another one subDoc1 under the subCol1 (sub-)collection

col1/doc1/subCol1/subDoc1

Actually, from a technical perspective, they are not at all relating to each other. They just share a part of their paths but nothing else.

You can very well create subDoc1 without creating doc1.

A side effect of this is that if you delete a document, its sub-collection(s) still exist. Again, the subcollection docs are not really linked to the parent document.