How do I remove an item from a nested array in Firestore?

Question

I want to remove the type 'A' from the capital. How do I do it? Any code example will be appreciated. I am working on a react project.

Answer 1

As far as I can tell there is nonestedarray in the document you shared. In that case you can use the arrayRemove operator to remove a unique item from the array:

const cityRef = doc(db, "cities", "capital");

await updateDoc(cityRef, {
    region: arrayRemove({ type: "A" })
});

A few things to note here:

• You can to pass the entire array item to the arrayRemove operator, as it only removes array items that exactly and completely match the value you pass.
• The arrayRemove operations removes all items that match. So if you have multiple { type: "A" } items in the array, all will be removed.
• This operation can only work on an array field at a known path, it cannot work on an array that is nested under another array.

If your use-case can't satisfy any of the requirements above, the way to remove the item would be to:

1. Load the document and get the array from it.
2. Update the array in your application code.
3. Write the entire top-level array back to the database.