翻译或纠错本页面
- Reference >
- Operators >
- Aggregation Pipeline Operators >
- String Aggregation Operators >
- $toUpper (aggregation)
$toUpper (aggregation)¶
On this page
Definition¶
- $toUpper¶
Converts a string to uppercase, returning the result.
$toUpper has the following syntax:
{ $toUpper: <expression> }
The argument can be any expression as long as it resolves to a string. For more information on expressions, see Expressions.
If the argument resolves to null, $toLower returns an empty string "".
Behavior¶
$toUpper only has a well-defined behavior for strings of ASCII characters.
Example¶
Consider a inventory collection with the following documents:
{ "_id" : 1, "item" : "ABC1", quarter: "13Q1", "description" : "PRODUCT 1" }
{ "_id" : 2, "item" : "abc2", quarter: "13Q4", "description" : "Product 2" }
{ "_id" : 3, "item" : "xyz1", quarter: "14Q2", "description" : null }
The following operation uses the $toUpper operator return uppercase item and uppercase description values:
db.inventory.aggregate(
[
{
$project:
{
item: { $toUpper: "$item" },
description: { $toUpper: "$description" }
}
}
]
)
The operation returns the following results:
{ "_id" : 1, "item" : "ABC1", "description" : "PRODUCT 1" }
{ "_id" : 2, "item" : "ABC2", "description" : "PRODUCT 2" }
{ "_id" : 3, "item" : "XYZ1", "description" : "" }