project

$project

Control the fields you want to include or not in the documents you pass to the next stage in the pipeline.

You can project with the following objectives:

• Include only specific fields
• Exclude specific fields
• Create a new field that has a computed value

Note: If you exclude fields, you cannot also specify fields to include.

Syntax

{ $project: { specification(s) } }

For more information, see the following specification examples:

Example	Result
{ $project: { field1: 1 } }	Only field1 and its value project to the next stage in the pipeline.
{ $project: { field1: 0 } }	All fields except field1 project to the next stage in the pipeline.
{ $project: { newField: { $add: ["field1", "field2"} }	Projects a newly created field, newField, with a computed value to the next stage in the pipeline.

Sample Request

[
	{
		"$match": {
			"temp": {
				"$exists": true
			}
		}
	},
	{
		"$project": {
			"temp": 1,
			"_ts": 1
		}
	},
	{
		"$sort": {
			"_ts": 1
		}
	},
	{
		"$limit": 3
	}
]

Sample Response

{
	"_list": [
		{
			"temp": 368,
			"_id": "645bca63f8b8a87c0f075ce9",
			"_ts": "Wed May 10 22:16:26 IST 2023"
		},
		{
			"temp": 871,
			"_id": "645bca63f8b8a87c0f075cea",
			"_ts": "Wed May 10 22:16:26 IST 2023"
		},
		{
			"temp": 777,
			"_id": "645bca63f8b8a87c0f075ceb",
			"_ts": "Wed May 10 22:16:27 IST 2023"
		}
	]
}