Data Security Blueprint: Lockdown Your JSON with TypeScript

Here’s a rewritten version of the article:

Securing Your Data with JSON Schema and TypeScript

In today’s complex web development landscape, transmitting data between applications is a common practice. JSON has proven to be an excellent standardized serialization process for exchanging wire data. However, this increased complexity raises concerns about data security. While JSON is flexible, it lacks built-in protection for your data. This uncertainty can be particularly problematic for applications that prioritize data security.

The Solution: JSON Schema

JSON Schema provides a solution to this security concern. It allows us to define a strict structure for the wire data transmitted between communicating applications. By using JSON Schema, we can ensure that the data we transmit adheres to a known schema, reducing the risk of errors and security breaches.

Why Use JSON Schema and TypeScript?

JSON Schema helps us define the structure of JSON data, specifying properties, data types, and validation rules. TypeScript, on the other hand, provides a static type-checking feature that validates the type consistency of variables, function parameters, and return values at compile-time. By using tools that convert TypeScript types into JSON Schemas, we can ensure our wire data adheres to a strict schema.

Generating JSON Schema from TypeScript Types

To generate JSON Schema from our defined TypeScript types, we’ll use the ts-json-schema-generator library. This library supports a wide range of TypeScript features, including interfaces, classes, enums, unions, and more.

Project Setup

Let’s start by creating a new project folder named json-schema-project and initializing a new project. Next, we’ll install the ts-json-schema-generator library.

Writing a TypeScript Interface

Within our project, let’s create a simple TypeScript file named types.ts and define a Person interface:
typescript
interface Person {
firstName: string;
lastName: string;
age: number;
socials: string[];
}

Using the ts-json-schema-generator Package

Now, let’s use the ts-json-schema-generator package to generate a JSON Schema for the Person interface. We’ll run the following command:
bash
npx ts-json-schema-generator --path src/types.ts --type Person

This command will generate a JSON Schema for the Person type. The resulting JSON object represents the generated JSON Schema:
json
{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "object",
"properties": {
"firstName": { "type": "string" },
"lastName": { "type": "string" },
"age": { "type": "number" },
"socials": { "type": "array", "items": { "type": "string" } }
},
"required": ["firstName", "lastName", "age", "socials"]
}

Using the Generated JSON Schema

Now that we have generated the JSON Schema, let’s see how to use it to validate data. We’ll create a middleware function to validate the wire data against the existing JSON Schema:

import Ajv from 'ajv';</p>

<p>const schema = {
  // generated JSON Schema
};</p>

<p>const validateFn = Ajv.compile(schema);</p>

<p>app.use('/users', (req, res, next) => {
  const { error } = validateFn(req.body);
  if (error) {
    return res.status(400).send({ error: 'Invalid request body' });
  }
  next();
});

Testing Our Implementation

Let’s test our implementation using Postman. We’ll send an unexpected request body to the /users endpoint and verify that it returns a 400 error response. Then, we’ll send the expected payload and verify that it returns a 200 status response.

By using JSON Schema and TypeScript, we can ensure that our data follows a rigorous schema and take advantage of TypeScript’s static type-checking. This approach helps prevent errors both client-side and server-side, ensuring that our data is both well-structured and type-safe.