Schema Validation

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New in version 3.2.

MongoDB provides the capability to perform schema validation during updates and insertions.

You can implement schema validation in the UI for deployments hosted in MongoDB Atlas.

Specify Validation Rules

Validation rules are on a per-collection basis.

To specify validation rules when creating a new collection, use db.createCollection() with the validator option.

To add document validation to an existing collection, use collMod command with the validator option.

MongoDB also provides the following related options:

validationLevel option, which determines how strictly MongoDB applies validation rules to existing documents during an update.
validationAction option, which determines whether MongoDB should error and reject documents that violate the validation rules or warn about the violations in the log but allow invalid documents.

JSON Schema

New in version 3.6.

Starting in version 3.6, MongoDB supports JSON Schema validation. To specify JSON Schema validation, use the $jsonSchema operator in your validator expression.

Note

JSON Schema is the recommended means of performing schema validation.

For example, the following example specifies validation rules using JSON schema:

db.createCollection("students", {
   validator: {
      $jsonSchema: {
         bsonType: "object",
         required: [ "name", "year", "major", "address" ],
         properties: {
            name: {
               bsonType: "string",
               description: "must be a string and is required"
            },
            year: {
               bsonType: "int",
               minimum: 2017,
               maximum: 3017,
               description: "must be an integer in [ 2017, 3017 ] and is required"
            },
            major: {
               enum: [ "Math", "English", "Computer Science", "History", null ],
               description: "can only be one of the enum values and is required"
            },
            gpa: {
               bsonType: [ "double" ],
               description: "must be a double if the field exists"
            },
            address: {
               bsonType: "object",
               required: [ "city" ],
               properties: {
                  street: {
                     bsonType: "string",
                     description: "must be a string if the field exists"
                  },
                  city: {
                     bsonType: "string",
                     description: "must be a string and is required"
                  }
               }
            }
         }
      }
   }
})

For more information, see $jsonSchema.

bsonType definitions can be found on the BSON Types page.

Other Query Expressions

In addition to JSON Schema validation that uses the $jsonSchema query operator, MongoDB supports validation with other query operators, with the exception of:

For example, the following example specifies validator rules using the query expression:

db.createCollection( "contacts",
   { validator: { $or:
      [
         { phone: { $type: "string" } },
         { email: { $regex: /@mongodb\.com$/ } },
         { status: { $in: [ "Unknown", "Incomplete" ] } }
      ]
   }
} )

Tip

query operators

Behavior

Validation occurs during updates and inserts. When you add validation to a collection, existing documents do not undergo validation checks until modification.

To perform validation checks on existing documents, use the validate command or the db.collection.validate() shell helper.

Existing Documents

The validationLevel option determines which operations MongoDB applies the validation rules:

If the validationLevel is strict (the default), MongoDB applies validation rules to all inserts and updates.
If the validationLevel is moderate, MongoDB applies validation rules to inserts and to updates to existing documents that already fulfill the validation criteria. With the moderate level, updates to existing documents that do not fulfill the validation criteria are not checked for validity.

For example, create a contacts collection with the following documents:

db.contacts.insert([
   { "_id": 1, "name": "Anne", "phone": "+1 555 123 456", "city": "London", "status": "Complete" },
   { "_id": 2, "name": "Ivan", "city": "Vancouver" }
])

Issue the following command to add a validator to the contacts collection:

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

The contacts collection now has a validator with the moderate validationLevel:

If you attempted to update the document with _id of 1, MongoDB would apply the validation rules since the existing document matches the criteria.
In contrast, MongoDB will not apply validation rules to updates to the document with _id of 2 as it does not meet the validation rules.

To disable validation entirely, you can set validationLevel to off.

Accept or Reject Invalid Documents

The validationAction option determines how MongoDB handles documents that violate the validation rules:

If the validationAction is error (the default), MongoDB rejects any insert or update that violates the validation criteria.
If the validationAction is warn, MongoDB logs any violations but allows the insertion or update to proceed.

For example, create a contacts2 collection with the following JSON Schema validator:

db.createCollection( "contacts2", {
   validator: { $jsonSchema: {
      bsonType: "object",
      required: [ "phone" ],
      properties: {
         phone: {
            bsonType: "string",
            description: "must be a string and is required"
         },
         email: {
            bsonType : "string",
            pattern : "@mongodb\.com$",
            description: "must be a string and match the regular expression pattern"
         },
         status: {
            enum: [ "Unknown", "Incomplete" ],
            description: "can only be one of the enum values"
         }
      }
   } },
   validationAction: "warn"
} )

With the warn validationAction, MongoDB logs any violations but allows the insertion or update to proceed.

For example, the following insert operation violates the validation rule:

db.contacts2.insert( { name: "Amanda", status: "Updated" } )

However, since the validationAction is warn only, MongoDB only logs the validation violation message and allows the operation to proceed:

2017-12-01T12:31:23.738-05:00 W STORAGE  [conn1] Document would fail validation collection: example.contacts2 doc: { _id: ObjectId('5a2191ebacbbfc2bdc4dcffc'), name: "Amanda", status: "Updated" }

Restrictions

You cannot specify a validator for collections in the admin, local, and config databases.

You cannot specify a validator for system.* collections.

Bypass Document Validation

Users can bypass document validation using the bypassDocumentValidation option.

The following commands can bypass validation per operation using the new option bypassDocumentValidation:

applyOps command
findAndModify command and db.collection.findAndModify() method
mapReduce command and db.collection.mapReduce() method
insert command
update command
$out and $merge stages for the aggregate command and db.collection.aggregate() method

For deployments that have enabled access control, to bypass document validation, the authenticated user must have bypassDocumentValidation action. The built-in roles dbAdmin and restore provide this action.

Additional Information

Tip

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