Using the MongoDB Java driver I would like to retrieve a validator defined for a collection. In mongo Shell this can be easily achieved by running db.getCollectionInfos({name: "MyTestCollection"})[0].options.validator; as described here.
What I miss is a similar method on the MongoDatabase class or a Database Command I can run with the MongoDatabase.runCommand(...) method.
What do I miss? How to retrieve that information in Java?
This is how I managed to retrieve the schema in question:
...
MongoDbJsonSchemaRetriever(MongoDatabase database) {
this.database = database;
}
Document retrieveJsonSchema(String collectionName) {
Document collection = database.listCollections().filter(byName(collectionName)).first();
return readJsonSchema(collection);
}
private Bson byName(String collectionName) {
return Filters.eq("name", collectionName);
}
private static Document readJsonSchema(Document collection) {
return collection.get("options", EMPTY).get("validator", EMPTY).get("$jsonSchema", EMPTY);
}
Usage is straightforward:
new MongoDbJsonSchemaRetriever(yourDatabase).retrieveJsonSchema(yourCollectionName)
You will retrieve either the schema or an empty document if no schema is defined/found.
Let me know if you have found a better way.