在 Kotlin 中从 Firebase Firestore 获取一个 Object

Question

I alredy searched here in the forum but i didn't find nothing like that. I want to get an Object from Firebase Firestore, but I can't manipulate the object that I am receiving. How can I separate the imageLink from the imageTitle ?

The database structure is:

The code I am using is:

firebaseFirestore.collection("image").get()
            .addOnSuccessListener { documentSnapshot ->
                val imageData = documentSnapshot.documents[0].data?.getValue("imageData")
            }

But, when I do that, I receive something like that:

How can I get the imageLink from the imageTitle separately?

Answer 1

You can try casting imageData as a Map as shown below:

db.collection("images").limit(1).get().addOnSuccessListener { querySnapshot ->
    val imageData =
        querySnapshot.documents[0].data!!.getValue("imageData")?.let { it as Map<*, *> }

    val imageLink = imageData?.get("imageLink")
    val imageTitle = imageData?.get("imageTitle")

    Log.d("MainActivity", "imageLink: $imageLink")
    Log.d("MainActivity", "imageTitle: $imageTitle")
}

Checkout the documentation for let for more information.

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You are calling get() on a CollectionReference that will fetch all documents from the collection (if you add any). If you only want to fetch 1st document from the collection, you can add limit(1) that'll save any additional charges.