Specify Validation Level for Existing Documents

Specify validation rules with moderate validation level.

Add a validator to the movies collection with moderate validationLevel:

db.runCommand( {
   collMod: "movies",
   validator: { $jsonSchema: {
      bsonType: "object",
      required: [ "title" ],
      properties: {
         title: {
            bsonType: "string",
            description: "title must be a string and is required"
         }
      }
   } },
   validationLevel: "moderate"
} )

Because the validationLevel is moderate, MongoDB applies the validation rules to all document inserts and to updates of existing documents that already meet the rules.

Insert a valid document.

The following insert command adds a document that includes a title field with a string value, which satisfies the validation rule:

db.movies.insertOne(
   { title: "Wings", year: 1927 }
)

Observe results.

The insert succeeds because the document satisfies the validation rules. MongoDB returns output similar to the following:

{
  acknowledged: true,
  insertedId: ...
}

Specify validation rules with strict validation level.

Add a validator to the movies collection with strict validationLevel:

db.runCommand( {
   collMod: "movies",
   validator: { $jsonSchema: {
      bsonType: "object",
      required: [ "title" ],
      properties: {
         title: {
            bsonType: "string",
            description: "title must be a string and is required"
         }
      }
   } },
   validationLevel: "strict"
} )

Because the validationLevel is strict, MongoDB applies the validation rules to all document inserts and updates.

Insert a valid document.

The following insert command adds a document that includes a title field with a string value, which satisfies the validation rule:

db.movies.insertOne(
   { title: "The Conversation", year: 1974 }
)

Observe results.

The insert succeeds because the document satisfies the validation rules. MongoDB returns output similar to the following:

{
  acknowledged: true,
  insertedId: ...
}

(Conditional) Set your validationLevel to strict.

If your collection's validationLevel is not already strict, follow the procedure to specify strict validation.

Prepare the collection for the constraint level.

Run collMod with prepareConstraintValidationLevel set to true:

db.runCommand( {
   collMod: "movies",
   prepareConstraintValidationLevel: true
} )

This command prepares the collection for the upgrade by blocking bypassDocumentValidation and preventing changes to the validator.

Set the validation level to constraint.

Run collMod to set the validationLevel to constraint. The validationAction must be error or errorAndLog:

db.runCommand( {
   collMod: "movies",
   validationLevel: "constraint",
   validationAction: "error"
} )

You can't change the validator in the same collMod operation that upgrades the validationLevel to constraint. Set the validation rules before you run this command. To change the rules later, downgrade the level to strict, modify the rules, and then upgrade back to constraint.

Because the validationLevel is constraint, MongoDB applies the validation rules to all document inserts and updates, regardless of whether an existing document met the rules before the upgrade.

When you set the level to constraint, MongoDB scans all existing documents in the collection and fails the collMod operation if any document violates the validator. This scan can be computationally expensive for large collections. If the operation fails, update the violating documents to pass the validator before you continue.

Insert a valid document.

The following insert command adds a document that includes a title field with a string value, which satisfies the validation rule:

db.movies.insertOne(
   { title: "Sunrise", year: 1927 }
)

Observe results.

The insert succeeds because the document satisfies the validation rules. MongoDB returns output similar to the following:

{
  acknowledged: true,
  insertedId: ...
}