@lambda-middleware/class-validator


A validation middleware for AWS http lambda functions based on class-validator and class-transformer.

Lambda middleware

This middleware is part of the lambda middleware series. It can be used independently.

Usage

``typescript
// When using decorators, don't forget to import this in the very first line of code
import "reflect-metadata";

import { classValidator } from '@lambda-middleware/class-validator'
import { composeHandler } from "@lambda-middleware/compose";
import { errorHandler } from "@lambda-middleware/http-error-handler";
import { IsString } from "class-validator";

// Define a validator for the body via class-validator
class NameBody {
constructor(firstName: string, lastName: string) {
this.firstName = firstName;
this.lastName = lastName;
}

@IsString()
public firstName: string;

@IsString()
public lastName: string;
}

// This is your AWS handler
async function helloWorld(event: { body: NameBody }) {
// Thanks to the validation middleware you can be sure body is typed correctly
return {
body: Hello ${event.body.firstName} ${event.body.lastName},
headers: {
"content-type": "text",
},
statusCode: 200,
};
}

// Let's add middleware to our handler, then we will be able to attach middlewares to it
export const handler = composeHandler(
// The class validator throws validation errors from http-errors which are compatible with
// the error handler middlewares for middy
errorHandler(),
classValidator({
// Add the validation class here
bodyType: NameBody,
// You can add options to class-transformer. These will be passed through,
// so read the class-transformer documentation for details
transformer: {},
// You can add options to class-validator. For security reasons,
// whitelist by default is set to true. If you set any options, you have
// to set it to true manually as the default for class-validator would be
// false
validator: {},
}),
helloWorld
);
``