Miscellaneous

Ajv JSON Schema Validator

Ajv, one of the best JSON schema validators, is extremely useful in the development of backend APIs for data validation. But Ajv is not supported by many edge environments, including Vercel, because of it's usage of eval. However, the SherpaJS compiler will pre-compile standalone Ajv schema, so schema validation can be done on the edge.

Example Static Schema

Start by creating a schema.json file containing the desired schema.

{
	"type": "object",
	"properties": {
		"foo": {
			"type": "number"
		}
	},
	"required": ["foo"],
	"additionalProperties": false
}

Then import your schema (in any script), and write the schema in the AJV function, provided by Sherpa Core.

import { Request, Response, AJV } from "sherpa-core";
import schemaFoo from "../../src/foo.schema.json";
const validatorFoo = AJV(schemaFoo);

export function POST(request:Request) {
    try {
        if (!validatorFoo(request.body)) {
            return Response.text(JSON.stringify(validatorFoo.errors));
        }
        return Response.text("OK");
    } catch (e) {
        console.log(e);
        return Response.text(e.toString());
    }
}

Environment Variables

Environment variables are a key part of configuring your SherpaJS application. They allow you to set various configuration options and secrets without hardcoding them into your application's codebase.

Loading Environment Variables

SherpaJS uses the .env file to load environment variables. This file should be placed at the root of your project. When the system is compiled, the variables defined in this file are automatically loaded into your server's environment.

Any environment variables provided by hosting services (such as Vercel or AWS) are automatically included in your build.

Environment varibles can also be added during build with the build command.

Automatic Parsing

SherpaJS automatically parses environment variables to their appropriate types:

• Strings remain as strings
• Booleans are converted to true or false
• Numbers are converted to numeric values

Example .env File

Here is an example of a .env file:

PORT=3000                                         # number
DATABASE_URL=mongodb://localhost:27017/mydatabase # string
JWT_SECRET=myverysecretkey                        # string
ENABLE_FEATURE_X=true                             # boolean
MAX_CONNECTIONS=100                               # number

Best Practices

• Security: Never commit your .env file to version control. Add it to your .gitignore file.
• Defaults: Provide sensible default values for environment variables in your code.
• Validation: Validate the presence and format of critical environment variables at the start of your application to avoid runtime errors.