Installation

NPM Packages

The FPInterceptor is distributed on NPM individually as @formulaic/fp-interceptor, or can be installed as part of @formulaic/api.

Add to Nest

You should add FPInterceptor as a global interceptor after creating a Nest server.

src/main.ts

import { NestFactory } from "@nestjs/core";
import { FPInterceptor } from "@formulaic/fp-interceptor";
import { AppModule } from "./app.module";

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useGlobalInterceptors(new FPInterceptor());
  await app.listen(3000);
}
bootstrap();

Configuration

The FPInterceptor constructor can be passed an optional object defining configuration options.

Class Transformer Groups

FP uses class-transformer groups under the hood to control data visibility - for instance, most debug information is only exposed if the "debug" group is enabled.

Set All Groups

Because FP internally uses a set of standard groups, FP Interceptor comes with shortcuts to enable certain groups.

However, you can use the groups option to explicitly set the entire list of groups.

Provide Additional Groups

If you use groups in your own output, we recommend specifying which groups should be enabled by providing additionalGroups instead of overriding all groups.

Debug and Info Output

As previously mentioned, FP marks data with the "debug" group, but also makes frequent use of "info".

You may wish to selectively control all the information that is sent to users, however the two presets offer a bit of functionality out of the gate.

Enabling "debug" will expose a large amount of information, including information that is very usually hidden from users.

However, FP exposes a selective set of information that may provide nice insight for developers and users by revealing some information about the system, without explicitly opening security vulnerabilities.

This includes things like the general area where an error originates (e.g. "database", or "filesystem"), and possibly the names of tables.

If you are relatively relaxed about security, "info" can be semi-safely enabled. However, highly-security-conscious environments may not want to use it.

Overview

Usage