TypeScript — Node.js

If you use TypeScript, you can specify a type for some classes in the driver.
All classes that accept a type parameter in the driver have the default type
Document. The Document interface has the following definition:

All object types extend the Document interface.

For more information on object types, see the
TypeScript handbook .

Keys not listed in your specified type parameter receive the any type. The following code snippet demonstrates this behavior:

You can pass a type parameter that extends the Document interface like this:

The following classes accept all types that extend the Document interface:

You can find a code snippet that shows how to specify a type for the FindCursor class in the Find Multiple Documents Usage Example .

Type Safety and Dot Notation

Starting in version 5.0, by default, the Node.js driver does not provide type
safety for operations that search on fields expressed in dot notation. Dot
notation is a syntax you can use to navigate nested JSON objects. When
you construct a filter to pass to a query, the driver will not raise a
type error even if you specify an incorrectly typed value for a field expressed
in dot notation.

The following code snippet defines the ClassificationPet interface,
which includes a classification field that enables you to specify the
genus and color of dogs and cats:

interface
 
ClassificationPet
  {  
name
: 
string
;  
age
: 
number
;  
classification
:  { 
genus
: 
"Canis"
  | 
"Felis"
; 
color
: 
string
 } ;}

The driver does not raise a type error for the following code sample,
even though the value of classification.color is a boolean
instead of a string:

await
 myColl.
findOneAndDelete
( { 
"classification.color"
: 
false
 }) ;

You can enable type-checking by constructing filters as StrictFilter or
StrictUpdateFilter types.

Warning

The StrictFilter and StrictUpdateFilter types are experimental and
may show type errors in valid queries where there should be none.

In the following code sample, the filter is assigned a
StrictFilter type. Given this filter type, the Node.js driver
reports a type error because the value of classification.color is a
boolean instead of a string.

const
 
filterPredicate
: 
StrictFilter
<
ClassificationPet
>  =  { 
"classification.color"
: 
false
 } ;
await
 myColl.
findOneAndDelete
( filterPredicate) ;

The following example assigns a StrictUpdateFilter type to an update
filter. The Node.js driver reports a type error because the value of
classification.color is a boolean instead of a string.

const
 
updateFilter
: 
StrictUpdateFilter
<
ClassificationPet
>  =  { 
$set
:  { 
"classification.color"
: 
false
 } }
await
 pets.
updateOne
( { } ,  updateFilter) ;

Referencing Keys that Incorporate Variables

If you need to query a collection or perform another operation with a
key that incorporates variables, you must use an as const
assertion when specifying the key. This mechanism allows your
code to compile successfully as long as the input types are correct.

The following code snippet defines the ClassificationPet interface
and the Mealtime interface. ClassificationPet includes a
mealtimes field that contains an array of Mealtime interfaces,
each of which includes a time field:

interface
 
ClassificationPet
  {  
name
: 
string
;  
mealtimes
: 
Mealtime
[ ] ;}
interface
 
Mealtime
{  
time
: 
string
;  
amount
: 
number
;}

The following code snippet performs a find-and-update operation on a
collection of ClassificationPet documents. The operation
updates the nested time field of the Mealtime instance at index
1. The index position is specified by the variable mealCounter:

const
 mealCounter  = 
1
;
await
 myColl.
findOneAndUpdate
(   { 
name
: 
"Lassie"
 } ,   { 
$set
:  {  [
`mealtimes.
${mealCounter}
.time`
 
as
 
const
] : 
'4:00 PM'
 } } ,) ;

To learn more about dot notation, see
Dot Notation
in the MongoDB manual.

To learn more about the limitations of dot notation in the
Node.js driver, see the
Recursive Types and Dot Notation
section.