Create a View with Default Collation¶

Collation allows you to specify language-specific rules for string comparison, such as rules for letter-case and accent marks.

This page explains how to specify a default collation for a view.

Example¶

Create a places collection with the following documents:

db.places.insertMany([
   { _id: 1, category: "café" }
   { _id: 2, category: "cafe" }
   { _id: 3, category: "cafE" }
])

The following operation creates a view, specifying collation at the view level:

db.createView(
   "placesView",
   "places",
   [ { $project: { category: 1 } } ],
   { collation: { locale: "fr", strength: 1 } }
)

The following operation uses the view’s collation:

db.placesView.count( { category: "cafe" } )

The operation returns 3.

Note

Collation Behavior

You can specify a default collation for a view at creation time. If no collation is specified, the view’s default collation is the “simple” binary comparison collator. That is, the view does not inherit the collection’s default collation.
String comparisons on the view use the view’s default collation. An operation that attempts to change or override a view’s default collation will fail with an error.
If creating a view from another view, you cannot specify a collation that differs from the source view’s collation.
If performing an aggregation that involves multiple views, such as with :pipeline:`$lookup` or :pipeline:`$graphLookup`, the views must have the same collation.