Object types and input types in NestJS - Performance & Optimization

Performance: Object types and input types

MEDIUM IMPACT

This concept affects server response time and client rendering speed by influencing how data is validated and transformed before processing.

Defining GraphQL object and input types for API requests

NestJS

import { ObjectType, Field, InputType } from '@nestjs/graphql';

@ObjectType()
export class User {
  @Field()
  name: string;

  @Field()
  age: number;
  // password field omitted from output type
}

@InputType()
export class CreateUserInput {
  @Field()
  name: string;

  @Field()
  age: number;

  @Field()
  password: string; // only in input type
}

Separating input and output types avoids sending sensitive data to clients and reduces payload size.

📈 Performance GainSmaller payloads improve network speed and reduce client rendering workload.

Defining GraphQL object and input types for API requests

NestJS

import { ObjectType, Field, InputType } from '@nestjs/graphql';

@ObjectType()
export class User {
  @Field()
  name: string;

  @Field()
  age: number;

  @Field()
  password: string; // included in output type
}

@InputType()
export class CreateUserInput {
  @Field()
  name: string;

  @Field()
  age: number;

  @Field()
  password: string;
}

Including sensitive fields like password in output object types causes unnecessary data exposure and larger payloads.

📉 Performance CostIncreases payload size, causing slower network transfer and longer client rendering times.

Performance Comparison

Pattern	Payload Size	Network Transfer	Client Parsing	Verdict
Including sensitive fields in output types	Large	Slower	More CPU	[X] Bad
Separating input and output types properly	Small	Faster	Less CPU	[OK] Good

Rendering Pipeline

Object and input types define the shape of data sent and received. Proper separation reduces data size, which speeds up network transfer and lowers client rendering time.

→Network Transfer

→Client Parsing

→Client Rendering

⚠️ BottleneckNetwork Transfer due to payload size

Core Web Vital Affected

INP

This concept affects server response time and client rendering speed by influencing how data is validated and transformed before processing.

Optimization Tips

1Always separate input types from output object types in GraphQL schemas.

2Exclude sensitive or unnecessary fields from output types to reduce payload size.

3Use input types to validate and accept data without exposing it back to clients.

Performance Quiz - 3 Questions

Why should sensitive fields like passwords be excluded from GraphQL output object types?

A To make the code shorter

B To reduce payload size and avoid exposing sensitive data

C To increase server CPU usage

D To make input types larger

DevTools: Network

How to check: Open DevTools, go to Network tab, inspect GraphQL request and response payload sizes.

What to look for: Look for smaller response sizes and faster transfer times indicating efficient object type usage.