removing an object from firestore 9 array using arrayRemove()?

Question

I am trying to remove an object from array in in firestore, but encountered an obstacle what are the requirement or the reference to do the removal ? does one key value in the object sufficient to do the remove or should the object by identical to the one that is getting removed ?

const deleteWeek = async () => {
        const docRef = doc(db, 'Weeks', id);
        await updateDoc(docRef, {
          weeks: arrayRemove({
            weekId: '7518005f-7b10-44b6-8e0a-5e41081ee064',
          }),
        });
      };
      deleteWeek();
    }

however week in data base looks like this

{name ,"Week 2"
days : [/*data all kinds*/]
weekId : "7518005f-7b10-44b6-8e0a-5e41081ee064"}

Dharmaraj · Accepted Answer · 2022-02-25 03:36:00Z

3

If it's an array of object, then you need to know the whole object to use arrayRemove() For example, if the a document looks like this:

{
  ...data
  weeks: [
    { 
      name: "Week 2",
      days: [/*data all kinds*/]
      weekId: "7518005f-7b10-44b6-8e0a-5e41081ee064"}
    }
  ]
}

You'll have to pass the entire week object in arrayRemove(). It might be better to store such data in sub-collections instead so you can query/delete a specific one.

edited Feb 25, 2022 at 3:36

answered Feb 25, 2022 at 3:34

Dharmaraj

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3 Comments

Richardson Over a year ago

including sub items ? like the data in the days array ?

Dharmaraj Over a year ago

@Richardson yes.

Richardson Over a year ago

@Richardson ofc with the data included !! otherwise it won't work !! are you new to firebase ??

EremesKim · Accepted Answer · 2023-02-08 05:38:02Z

Since there is no function in firestore to delete only a element in array, you need to make arrayRemove refer to the same object you want to delete, then create a new object and insert it with arrayUnion method

in my case, i use to below

 const { leave,date,email } = req.body;

  const attendanceRef = admin.firestore().collection('Attendance').doc(`${email}`);
  
  const attendanceData = await attendanceRef.get();

  const attendanceRecord = attendanceData.data().attendance;

  const removeTarget = attendanceRecord.find((item) => item.date === date);

  await attendanceRef.update({
    attendance: admin.firestore.FieldValue.arrayRemove(removeTarget),
  })

  const obj = {
    ...removeTarget,
    "leave": leave,
  }

  await attendanceRef.set({
    attendance: admin.firestore.FieldValue.arrayUnion(obj),
  },{ merge: true })
  const newAttendance = await attendanceRef.get();
  const newAttendanceRecord = newAttendance.data().attendance;

  return await res.json({
    message: '퇴근시간이 저장되었습니다.',
    attendance:newAttendanceRecord
  });

after update, it maybe if error occured. if error occured, you need all working cancel. this case, you may want to use batch method

const admin = require('firebase-admin');


module.exports = async function(req,res) {
  const { leave,date,email } = req.body;

  const batch = admin.firestore().batch();

  const attendanceRef = admin.firestore().collection('Attendance').doc(`${email}`);
  
  const attendanceData = await attendanceRef.get();

  const attendanceRecord = attendanceData.data().attendance;

  const removeTarget = attendanceRecord.find((item) => item.date === date);

  // await attendanceRef.update({
  //   attendance: admin.firestore.FieldValue.arrayRemove(removeTarget),
  // })
  batch.update(
    attendanceRef,{ attendance: admin.firestore.FieldValue.arrayRemove(removeTarget) }
  )

  const obj = {
    ...removeTarget,
    "leave": leave,
  }
  
  // await attendanceRef.set({
  //   attendance: admin.firestore.FieldValue.arrayUnion(obj),
  // },{ merge: true })
  batch.set(
    attendanceRef, { attendance: admin.firestore.FieldValue.arrayUnion(obj) },{ merge: true }
  )


  await batch.commit();

  const newAttendance = await attendanceRef.get();
  const newAttendanceRecord = newAttendance.data().attendance;
  return await res.json({message: '퇴근시간이 저장되었습니다.',attendance:newAttendanceRecord});
}

hope help this for you

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