README
middy-extended-validator
Middy 2.0+ middleware that extends the included validator middleware.
Adds:
- Extended validation error messages (with details)
- Allow mounting a JSON schema file under a
body
root property. This allow using the JSON schema file to server as schema for the actual request not just the request as received in a lambda function.
Getting Started
Installing middy-extended-validator
npm install --save @middy/core
npm install --save middy-extended-validator
Usage
const middy = require('@middy/core');
const httpErrorHandler = require('@middy/http-error-handler');
const jsonBodyParser = require('@middy/http-json-body-parser');
const validator = require('middy-extended-validator');
const schema = require('some-json-schema.json');
const handler = async event => {
// do something with event.body...
const statusCode = 200;
const body = JSON.stringify({ message: 'something' })
return {
statusCode,
body,
};
};
module.exports.handler = middy(handler)
.use(jsonBodyParser())
.use(validator({ inputSchema: schema, mountSchemaAtBody: true, detailedErrors: true }))
.use(httpErrorHandler());
Options
The middleware accepts the following options:
mountSchemaAtBody
The mountSchemaAtBody
takes the inputSchema and mounts its properties under a body
property in the root.
Allows using a schema such as:
const schema = {
type: 'object',
properties: {
foo: { type: 'string' }
},
required: ['foo'],
}
and turns it into this:
const schema = {
type: 'object',
properties: {
body: { type: 'object' },
properties: {
foo: { type: 'string' }
}
required: ['foo'],
},
require: ['body']
}
which corresponds to how the event
actually looks as received in the lambda function.
This is especially useful if the schema is defined externally and also used for generating documentation for example.
detailedErrors
The default message returned by the included validator is just that validation failed (Event object failed validation).
The detailedErrors
option instead returns a
http-errors compatible object that
includes both a message as well as a details property which are both
returned to the client as JSON.
For example:
{
"details:" "should have required property foo",
"message": "Event object failed validation"
}