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MongoDB allows users to rename fields in a document using the ‘$rename’ operator. This can be done in three ways – renaming a single field, renaming multiple fields, and renaming fields within a nested document. The syntax used to rename fields is the same regardless of the approach taken. To execute a rename operation, the db.collection.update() method is used, and the ‘$rename’ operator is used to specify the old and new field names. This allows users to efficiently manage the data in their MongoDB documents.
You can use the following methods to rename fields in MongoDB:
Method 1: Rename One Field
db.collection.updateMany({}, {$rename:{"oldField":"newField"}}, false, true)
Method 2: Rename Multiple Fields
db.collection.updateMany({}, {$rename:{"old1":"new1", "old2":"new2"}}, false, true)
Method 3: Rename Subfield
db.collection.updateMany({}, {$rename:{"field.oldSub":"field.newSub"}}, false, true)
Note that the false, true in the $rename function stands for {upsert:false, multi:true}.
You need the multi:true to update the field name in all of your documents.
The following examples show how to use each method with a collection teams with the following documents:
db.teams.insertOne({team: "Mavs", class: {conf:"Western", div:"A"}, points: 31})
db.teams.insertOne({team: "Spurs", class: {conf:"Western", div:"A"}, points: 22})
db.teams.insertOne({team: "Jazz", class: {conf:"Western", div:"B"}, points: 19})
db.teams.insertOne({team: "Celtics", class: {conf:"Eastern", div:"C"}, points: 26})
db.teams.insertOne({team: "Cavs", class: {conf:"Eastern", div:"D"}, points: 33})
db.teams.insertOne({team: "Nets", class: {conf:"Eastern", div:"D"}, points: 38})
Example 1: Rename One Field
We can use the following code to rename the team field to new_team:
db.teams.updateMany({}, {$rename:{"team":"new_team"}}, false, true)
Here are what the documents look like now:
{ _id: ObjectId("62017ce6fd435937399d6b58"),
class: { conf: 'Western', div: 'A' },
points: 31,
new_team: 'Mavs' }
{ _id: ObjectId("62017ce6fd435937399d6b59"),
class: { conf: 'Western', div: 'A' },
points: 22,
new_team: 'Spurs' }
{ _id: ObjectId("62017ce6fd435937399d6b5a"),
class: { conf: 'Western', div: 'B' },
points: 19,
new_team: 'Jazz' }
{ _id: ObjectId("62017ce6fd435937399d6b5b"),
class: { conf: 'Eastern', div: 'C' },
points: 26,
new_team: 'Celtics' }
{ _id: ObjectId("62017ce6fd435937399d6b5c"),
class: { conf: 'Eastern', div: 'D' },
points: 33,
new_team: 'Cavs' }
{ _id: ObjectId("62017ce6fd435937399d6b5d"),
class: { conf: 'Eastern', div: 'D' },
points: 38,
new_team: 'Nets' }
Notice that the team field has been renamed to new_team for every document.
Example 2: Rename Multiple Fields
We can use the following code to rename the team field to new_team and the points field to new_points:
db.teams.updateMany({}, {$rename:{"team":"new_team", "points":"new_points"}}, false, true)
Here are what the documents look like now:
{ _id: ObjectId("62017ce6fd435937399d6b58"),
class: { conf: 'Western', div: 'A' },
new_team: 'Mavs',
new_points: 31 }
{ _id: ObjectId("62017ce6fd435937399d6b59"),
class: { conf: 'Western', div: 'A' },
new_team: 'Spurs',
new_points: 22 }
{ _id: ObjectId("62017ce6fd435937399d6b5a"),
class: { conf: 'Western', div: 'B' },
new_team: 'Jazz',
new_points: 19 }
{ _id: ObjectId("62017ce6fd435937399d6b5b"),
class: { conf: 'Eastern', div: 'C' },
new_team: 'Celtics',
new_points: 26 }
{ _id: ObjectId("62017ce6fd435937399d6b5c"),
class: { conf: 'Eastern', div: 'D' },
new_team: 'Cavs',
new_points: 33 }
{ _id: ObjectId("62017ce6fd435937399d6b5d"),
class: { conf: 'Eastern', div: 'D' },
new_team: 'Nets',
new_points: 38 }
Notice that the team field and the points field have both been renamed in each document.
Example 3: Rename Subfield
We can use the following code to rename the div subfield within the class field to division:
db.teams.updateMany({}, {$rename:{"class.div":"class.division"}}, false, true)
Here are what the documents look like now:
{ _id: ObjectId("62017e21fd435937399d6b5e"),
team: 'Mavs',
class: { conf: 'Western', division: 'A' },
points: 31 }
{ _id: ObjectId("62017e21fd435937399d6b5f"),
team: 'Spurs',
class: { conf: 'Western', division: 'A' },
points: 22 }
{ _id: ObjectId("62017e21fd435937399d6b60"),
team: 'Jazz',
class: { conf: 'Western', division: 'B' },
points: 19 }
{ _id: ObjectId("62017e21fd435937399d6b61"),
team: 'Celtics',
class: { conf: 'Eastern', division: 'C' },
points: 26 }
{ _id: ObjectId("62017e21fd435937399d6b62"),
team: 'Cavs',
class: { conf: 'Eastern', division: 'D' },
points: 33 }
{ _id: ObjectId("62017e21fd435937399d6b63"),
team: 'Nets',
class: { conf: 'Eastern', division: 'D' },
points: 38 }
Notice that the div subfield within the class field has been renamed to division in each document.
Note: You can find the complete documentation for the $rename function .
The following tutorials explain how to perform other common operations in MongoDB: