Field

High-level, typesafe pointer to a specific field in a document.

This type may refer to fields nested in children documents or arrays. Instances are generally used to refer to a MongoDB field we want to read or update, when writing requests.

Type safety

This type is responsible for ensuring type safety:

class User(
    val _id: ObjectId,
    val profile: Profile,
    val friends: List<Friend>,
)

class Profile(
    val name: String,
)

class Friend(
    val name: String,
    val age: Int,
)

// Refer to the user's id
println(User::_id.field)
// _id

// Refer to the user's name
println(User::profile / Profile::name)
// profile.name

// Refer to the name of the second friend
println(User::friends[1] / Friend::name)
// friends.1.name

An instance of FieldDsl is required in scope to call these methods. All KtMongo commands automatically bring an instance of FieldDsl into scope.

For example, when writing a filter, methods from this interface are automatically available:

collection.find {
    User::profile / Profile::name eq "Thibault Lognaise"
}

To bypass type-safety, and refer to arbitrary fields without declaring them first, see unsafe.

Parameters