How to copy one collection to another by adding a field in MongoDB?
Is there a way to copy one collection to another in MongoDB while adding a new field?
Yes, it is possible to copy one collection to another in MongoDB by adding a field using the $addFields pipeline stage in the aggregation framework. Here is an example of how you can do it:
Suppose we have two collections named source_collection and target_collection, and we want to copy data from source_collection to target_collection by adding a new field called new_field.
Sample source_collection documents:
{
"_id": 1,
"name": "John",
"age": 25
},
{
"_id": 2,
"name": "Jane",
"age": 30
},
{
"_id": 3,
"name": "Bob",
"age": 40
}
We want to copy this collection to a new collection named target_collection by adding a new field new_field which contains a string value.
The following MongoDB aggregation pipeline can be used to achieve this:
db.source_collection.aggregate([
{
$addFields: {
new_field: "new value"
}
},
{
$out: "target_collection"
}
])
This pipeline adds a new field called new_field to each document in the source_collection with a value of "new value". The $out stage then writes the output to the target_collection.
The resulting documents in target_collection will look like this:
{
"_id": 1,
"name": "John",
"age": 25,
"new_field": "new value"
},
{
"_id": 2,
"name": "Jane",
"age": 30,
"new_field": "new value"
},
{
"_id": 3,
"name": "Bob",
"age": 40,
"new_field": "new value"
}
