MongoDB recently introduced, with its version 3.6, a validation capability
using JSON Schema syntax. As we keep
hearing that one of the great benefits of NoSQL is the absence of schema, isn’t
this new feature an admission of the limitations of NoSQL databases? The answer is a resounding NO: schema validation actually brings the
best of both worlds to NoSQL databases!
Previously with version 3.2, MongoDB had introduced
a validation capability, using their Aggregation
Framework syntax. This was in
response to the request of enterprises wishing to leverage the benefits of
NoSQL, without risk of losing control of their data. JSON Schema
is the schema definition standard for JSON files, sort of the equivalent of XSD
for XML files. So, it was only natural
that MongoDB would adopt the JSON Schema standard. There are multiple reasons to leverage this
capability:
1) Enforcing schema only when it matters: with JSON
Schema, you can declare fields where you want enforcement to take place. And let other fields be added with no
enforcement at all, by using the property: ‘AdditionalProperties’. Some fields are more important than others in
a document. In particular in the context
of privacy laws and GDPR, you may want to track some aspects of your schema and
ensure consistency. You may also want to
control data quality with field constraints such as string length or regular
expression, numeric upper and lower limits, etc…
2) JSON polymorphism: having a schema declared and
enforced does not at all limit you in your ability to have multi-type fields or
flexible polymorphic structures. It only
makes sure that they do not occur as a result of development mistakes. JSON Schema, with oneOf/anyOf/allOf/noneOf
choices, lets you declare in your validation rules exactly what is allowed and
what is not allowed.
3) Degree of enforcement: MongoDB lets you decide,
for each collection, the validation level (off, strict or moderate), and the
validation action to be returned by the database through the driver (warning or
error.)
In effect, the $jsonschema validator becomes the equivalent of a DDL (data
definition language) for NoSQL databases, letting you apply just the right level
of control to your database.
Since Hackolade was built from the ground up on JSON Schema, it has been quite easy to maintain MongoDB certification as a result of this v3.6 enhancement. No JSON Schema knowledge is required! You build your collection model with a few mouse clicks, and Hackolade dynamically generates the JSON Schema script for creation or update of the collection validator.
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| Hackolade model dynamically generates MongoDB $jsonschema validator |
