ParseFilePipeBuilder

Kind: Class

Source: packages/common/pipes/file/parse-file-pipe.builder.ts

Part of: Common

ParseFilePipeBuilder provides a fluent API for configuring and creating a ParseFilePipe for uploaded-file validation. It collects file validators—such as maximum size and allowed file type—and builds a pipe that can be applied to @UploadedFile() parameters in NestJS controllers.

Methods

Diagram

mermaid
graph LR
  A[ParseFilePipeBuilder] --> B[addMaxSizeValidator]
  A --> C[addFileTypeValidator]
  A --> D[addValidator]
  B --> E[Validator collection]
  C --> E
  D --> E
  E --> F[build]
  F --> G[ParseFilePipe]
  G --> H[@UploadedFile() validation]

Usage

ts
import {
  Controller,
  HttpStatus,
  Post,
  UploadedFile,
  UseInterceptors,
} from '@nestjs/common';
import { FileInterceptor } from '@nestjs/platform-express';
import { ParseFilePipeBuilder } from '@nestjs/common';

@Controller('uploads')
export class UploadController {
  private readonly imageUploadPipe = new ParseFilePipeBuilder()
    .addFileTypeValidator({
      fileType: /(jpg|jpeg|png)$/,
    })
    .addMaxSizeValidator({
      maxSize: 5 * 1024 * 1024, // 5 MB
    })
    .build({
      errorHttpStatusCode: HttpStatus.UNPROCESSABLE_ENTITY,
    });

  @Post('image')
  @UseInterceptors(FileInterceptor('file'))
  uploadImage(@UploadedFile(this.imageUploadPipe) file: Express.Multer.File) {
    return {
      filename: file.filename,
      mimetype: file.mimetype,
      size: file.size,
    };
  }
}

AI Coding Instructions

• Use the fluent builder chain to add validators before calling build(); build() returns the ParseFilePipe used by controller parameters.
• Prefer addMaxSizeValidator() and addFileTypeValidator() for standard upload constraints; use addValidator() for custom FileValidator implementations.
• Configure size limits in bytes and ensure file-type rules match the formats accepted by the upload endpoint.
• Pass pipe-level options, such as errorHttpStatusCode or fileIsRequired, to build() rather than embedding them in individual validators.
• Reuse a built pipe when multiple endpoints share the same validation policy, but create separate builders for endpoint-specific rules.

Used by

1 reference from 1 file. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (1)

• AppController — sample/29-file-upload/src/app.controller.ts:15