Niveles y acciones de validación
Configurará validationLevel (strict frente a moderate) y validationAction (error frente a warn) para controlar cómo se gestionan las infracciones.
Niveles y acciones de validación es una lección gratuita de MongoDB Academy en CoddyKit. Esta es la lección 3 de 4. Puedes leer la lección completa abajo gratuitamente — luego la practicas en el navegador con un editor de código integrado y un tutor de IA 24/7. Forma parte de la ruta de aprendizaje de MongoDB Academy, y tu progreso se sincroniza en la web y la app de CoddyKit. El curso de MongoDB Academy incluye 4 lecciones en total.
Partes de esta lección aún no han sido traducidas y se muestran en inglés.
Controlling How Strict Validation Is
MongoDB gives you two independent knobs to tune schema validation behaviour: validationLevel controls which documents are subject to validation, while validationAction controls what happens when a document fails validation. Together they let you introduce validation gradually into existing collections without breaking current data or applications.
validationLevel: strict
strict is the default validation level. In strict mode, every insert and every update must pass the validator—no exceptions. If an existing document in the collection already violates the schema, attempting to update it will still be checked against the validator. Strict mode gives you the strongest data quality guarantee but can be disruptive when applied to a collection with legacy non-conforming documents.
db.runCommand({
collMod: 'users',
validator: { $jsonSchema: { /* ... */ } },
validationLevel: 'strict' // default — all inserts and updates must pass
});validationLevel: moderate
moderate level applies the validator only to new inserts and to updates of documents that already pass the validator. Existing non-conforming documents can still be updated without being forced to comply. This is a safe migration path: you enable the validator on a live collection without breaking updates to old documents that don't yet match the new schema.
db.runCommand({
collMod: 'users',
validator: { $jsonSchema: { /* ... */ } },
validationLevel: 'moderate' // existing non-conforming docs can still be updated
});validationLevel: off
Setting validationLevel to off disables validation entirely, even if a validator is attached to the collection. This is useful during bulk data migrations or emergency hotfixes where you need to write non-conforming data temporarily. Always re-enable validation after the migration window closes.
// Temporarily disable validation for a migration window
db.runCommand({
collMod: 'users',
validationLevel: 'off'
});
// ... run migration ...
// Re-enable strict validation
db.runCommand({
collMod: 'users',
validationLevel: 'strict'
});validationAction: error
error is the default validation action. When a document fails validation, MongoDB rejects the write entirely and returns an error to the client. The document is not written. This is the safest setting for production because it prevents malformed data from ever entering the collection.
db.runCommand({
collMod: 'orders',
validator: { $jsonSchema: { /* ... */ } },
validationAction: 'error' // default: reject the write, return an error
});validationAction: warn
warn action allows the document to be written even if it fails validation, but logs a warning message to the MongoDB server log. This is useful during a transition period when you want to observe how many violations occur without blocking existing application traffic. After examining the logs and fixing the offenders, you can switch to error action.
db.runCommand({
collMod: 'legacy_collection',
validator: { $jsonSchema: { /* ... */ } },
validationAction: 'warn' // write succeeds, violation logged to server log
});
// The server log will show:
// [conn1] Document failed validation: { ... } with schema: { ... }Combining Level and Action
The two settings compose independently. A common migration strategy is to start with validationLevel: 'moderate' and validationAction: 'warn'—new documents must comply but get logged on failure, while old documents are untouched. After observing the warnings and backfilling old data, switch to strict + error for full enforcement.
// Phase 1: observe without blocking
db.runCommand({
collMod: 'users',
validator: { $jsonSchema: { bsonType: 'object', required: ['email'] } },
validationLevel: 'moderate',
validationAction: 'warn'
});
// Phase 2 (after backfill): full enforcement
db.runCommand({
collMod: 'users',
validationLevel: 'strict',
validationAction: 'error'
});Reading the Validation Configuration
Check the current validation settings on a collection using db.getCollectionInfos(). The response includes options.validationLevel and options.validationAction alongside the full validator document. This is useful to audit all collections in a database and verify that production collections have strict enforcement enabled.
const info = db.getCollectionInfos({ name: 'users' });
const opts = info[0].options;
console.log('level:', opts.validationLevel);
console.log('action:', opts.validationAction);
console.log('validator:', JSON.stringify(opts.validator, null, 2));Bypassing Validation With bypassDocumentValidation
Certain database operations support a bypassDocumentValidation: true option that skips the validator for that specific write. Only users with the bypassDocumentValidation privilege can use this option. It is intended for trusted admin scripts and data migrations only—never use it in application code as it defeats the purpose of having a validator.
// Insert a document bypassing validation — admin/migration use only
db.users.insertOne(
{ name: 'LegacyUser' }, // missing required email
{ bypassDocumentValidation: true }
);Validation Warnings in the Server Log
When validationAction is warn, each failed validation is written to the MongoDB server log with the WRITE component and WARNING severity. The log line includes the database, collection, the violating document's _id, and the specific schema rule that was broken. You can monitor these logs with Atlas's log viewer or by tailing mongod.log on self-hosted deployments.
Practical Migration Playbook
Here is the recommended four-phase playbook for adding validation to an existing production collection:
- Phase 1: Set
moderate+warn— no impact, observe violations - Phase 2: Fix application code to send compliant documents
- Phase 3: Backfill old non-conforming documents with a migration script
- Phase 4: Switch to
strict+error— full enforcement
Quick Check
Test your understanding of MongoDB & NoSQL Databases concepts from this lesson.
Lesson Recap
In this lesson you learned: validationLevel (strict/moderate/off) controls which documents are validated, validationAction (error/warn) controls whether failures block or just log, and combining moderate + warn is the safest way to introduce validation on a live collection. Next up we learn how to evolve schemas without downtime on a running MongoDB cluster.
Preguntas frecuentes
¿La lección «Niveles y acciones de validación» es gratis?
Sí — el texto completo de «Niveles y acciones de validación» es gratis para leer aquí en la web. Para practicarla de forma interactiva (editor de código integrado y tutor de IA 24/7) y desbloquear el resto del curso de MongoDB Academy, actualiza a CoddyKit PRO. El curso de MongoDB Academy incluye 4 lecciones en total.
¿Qué aprenderé en «Niveles y acciones de validación»?
Configurará validationLevel (strict frente a moderate) y validationAction (error frente a warn) para controlar cómo se gestionan las infracciones. Practicas MongoDB Academy con código real que ejecutas directamente en el navegador, y un tutor de IA 24/7 responde tus preguntas mientras trabajas en la lección.
¿Necesito experiencia previa para empezar MongoDB Academy?
No se requiere experiencia previa. MongoDB Academy en CoddyKit está estructurado para principiantes hasta estudiantes avanzados, así que puedes empezar aquí o desde el inicio y avanzar a tu ritmo. Esta es la lección 3 de 4.
¿Cuánto tiempo toma la lección «Niveles y acciones de validación»?
La mayoría de las lecciones de CoddyKit toman alrededor de 5–10 minutos. Cada una es compacta e interactiva, así que avanzas constantemente y retomas exactamente por donde dejaste en la web y la app.
¿Puedo escribir y ejecutar código en esta lección de MongoDB Academy?
Sí. Cada lección de MongoDB Academy incluye un editor de código integrado, así que escribes y ejecutas código real directamente en tu navegador y obtienes retroalimentación instantánea de IA — sin configuración local necesaria.
Todas las lecciones de este curso
- Añadir un validador a una colección
- Restricciones de tipo, obligatoriedad y enumeración
- Niveles y acciones de validación
- Evolucionar esquemas sin tiempo de inactividad