CODEWITHSUNDEEP
iosfirebasegoogle-cloud-firestoreswift4
azim vaziri
azim vaziri

Reputation: 153

How can i update an object (map) in an array with swift in firestore database?

I want to update a field of an object that the object is in an array in the Firestore database with Swift 4. These two functions (arrayUnion() and arrayRemove() ) are not working for me.

Here my Database schema:

ScreenShot

I want to update the "Status" field in The first array element.

Upvotes: 1

Views: 2688

Answers (3)

Jay
Jay

Reputation: 35648

I believe the question is:

how can I update a specific field that's stored within a document in an array.

As long as you know the documentId to the document you want to update - here's the solution.

Assuming a structure similar to what's in the question

Friends (a collection)
   0 (a document)
      Name: "Simon"
      Status: "Sent"
   1
      Name: "Garfunkle"
      Status: "Unsent"

and say we want to change Garfunkle's status to Sent

I will include one function to read document 1, Garfunkle's and then a second fuction to update the Status to sent.

Read the document at index 1 and print it's fields - this function is just for testing to show the field's values before and after changing the status field.

func readFriendStatus() {
    let docRef = self.db.collection("Friends").document("1")
    docRef.getDocument(completion: { document, error in
        if let document = document, document.exists {
            let name = document.get("Name") ?? "no name"
            let status = document.get("Status") ?? "no status"
            print(name, status)
        } else {
            print("no document")
        }
    })
}

and the output

Garfunkle Unsent

then the code to update the Status field to Sent

func writeFriendStatus() {
    let data = ["Status": "Sent"]
    let docRef = self.db.collection("Friends").document("1")
    docRef.setData(data, merge: true)
}

and the output

Garfunkle, Sent

Upvotes: 1

azim vaziri
azim vaziri

Reputation: 153

first of all I want to thanks to @Doug Stevenson for his kindly response. in my case, I must change the array of the objects to sub collections.

Upvotes: 1

Doug Stevenson
Doug Stevenson

Reputation: 317362

In a transaction, fetch the document, modify the field of the object as you see fit in memory on the client, then update that entire field back to the document.

Upvotes: 0

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