Deleting fields in Firebase - Step-by-Step Execution

Process Flow - Deleting fields

Start with document

↓

Specify field to delete

↓

Apply delete operation

↓

Field removed from document

↓

Save updated document

This flow shows how a field is removed from a document by specifying it and applying a delete operation, then saving the updated document.

Execution Sample

Firebase

docRef.update({
  fieldToDelete: firebase.firestore.FieldValue.delete()
});

This code deletes the field named 'fieldToDelete' from the document referenced by docRef.

Process Table

Step	Action	Field State Before	Operation	Field State After
1	Start with document	{fieldToDelete: 'value', otherField: 123}	None	{fieldToDelete: 'value', otherField: 123}
2	Specify field to delete	{fieldToDelete: 'value', otherField: 123}	Mark for deletion	Marked for deletion
3	Apply delete operation	Marked for deletion	Delete fieldToDelete	Field removed
4	Save updated document	{otherField: 123}	Save	{otherField: 123}

💡 Field 'fieldToDelete' is removed; document saved without it.

Status Tracker

Variable	Start	After Step 2	After Step 3	Final
documentData	{fieldToDelete: 'value', otherField: 123}	{fieldToDelete: 'value', otherField: 123}	{otherField: 123}	{otherField: 123}

Key Moments - 2 Insights

Why does the field still appear before saving?

Before saving (Step 3), the field is only marked for deletion but still exists in memory. It is removed only after the update operation completes and the document is saved (Step 4).

Can we delete multiple fields at once?

Yes, you can specify multiple fields with delete operations in the update call. Each field marked with FieldValue.delete() will be removed together.

Visual Quiz - 3 Questions

Look at the execution table, what is the state of 'fieldToDelete' after Step 2?

A Field removed from document

B Field marked for deletion but still present

C Field unchanged

D Field value updated

💡 Hint

Check the 'Field State After' column for Step 2 in the execution table.

At which step does the field actually get removed from the document?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Operation' and 'Field State After' columns in the execution table.

If you want to delete two fields at once, how would the update call change?

A Pass both fields with FieldValue.delete() in one update call

B Call update twice, once per field

C Use set() instead of update()

D Delete fields manually in the database UI

💡 Hint

Refer to the key moment about deleting multiple fields.

Concept Snapshot

Deleting fields in Firebase:
- Use update() with FieldValue.delete() on the field.
- Field is marked for deletion, then removed on save.
- Multiple fields can be deleted in one update.
- Document updates atomically without the deleted fields.

Full Transcript

This visual execution shows how to delete a field from a Firebase document. First, the document contains the field. Then, the field is specified for deletion using FieldValue.delete(). The field is marked for deletion but still present in memory until the update operation completes. After applying the delete operation, the field is removed from the document. Finally, the updated document is saved without the deleted field. Multiple fields can be deleted at once by including them in the update call with FieldValue.delete().