Question 119471 in Firebase Question posted in
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Firebase – How do I remove an item from a nested array in Firestore?

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.

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2

Answers


  1. 0

    As far as I can tell there is no nested array 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.
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  2. 0
    1. you have to get the doc and clone properties into temporary object
    2. you modify your temp object (remove item form region array)
    3. update original doc with temp object

    a cleanest way is to do that throught a firestore/transaction

    a small example to have a small approach

    const doc = await cityRef('cities/capital').get()
const temp =  JSON.parse(JSON.stringify(doc.data()))
temp.region = temp.region.filter(item => item.type !== 'A')
await cityRef('cities/capital').update(temp)
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