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fix(pipes): add parse-file pipe #8965

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fix(pipes): add parse-file pipe #8965

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7a0c985
fix(pipes): add parse-file pipe
coolsamk7 Jan 19, 2022
46ac18c
fix(pipes): fix the imports
coolsamk7 Jan 19, 2022
919511c
fix(pipes): fix the imports
coolsamk7 Jan 19, 2022
fa82380
Update packages/common/pipes/parse-file.pipe.ts
coolsamk7 Mar 29, 2022
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5 changes: 3 additions & 2 deletions packages/common/pipes/index.ts
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Original file line number Diff line number Diff line change
@@ -1,8 +1,9 @@
export * from './default-value.pipe';
export * from './parse-array.pipe';
export * from './parse-bool.pipe';
export * from './parse-int.pipe';
export * from './parse-float.pipe';
export * from './parse-enum.pipe';
export * from './parse-file.pipe';
export * from './parse-float.pipe';
export * from './parse-int.pipe';
export * from './parse-uuid.pipe';
export * from './validation.pipe';
76 changes: 76 additions & 0 deletions packages/common/pipes/parse-file.pipe.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,76 @@
import { Injectable, Optional } from '../decorators/core';
import { HttpStatus } from '../enums';
import {
ErrorHttpStatusCode,
HttpErrorByCode,
} from '../utils/http-error-by-code.util';
import {
ArgumentMetadata,
PipeTransform,
} from '../interfaces/features/pipe-transform.interface';

export interface FileValidationOptions {
fileType?: string;
maxFileSize?: number;
}

export interface ParseFileOptions {
fileType?: string;
maxFileSize?: number;
errorHttpStatusCode?: ErrorHttpStatusCode;
exceptionFactory?: (error: string) => any;
}

@Injectable()
export class ParseFile implements PipeTransform<any> {
protected exceptionFactory: (error: string) => any;
protected validationOptions: FileValidationOptions;

constructor(@Optional() options?: ParseFileOptions = {} ) {
const {
exceptionFactory,
errorHttpStatusCode = HttpStatus.BAD_REQUEST,
fileType,
maxFileSize,
} = options;

this.validationOptions = {
maxFileSize: maxFileSize,
fileType: fileType,
};

this.exceptionFactory =
exceptionFactory ||
(error => new HttpErrorByCode[errorHttpStatusCode](error));
}

async transform(value: any, metadata: ArgumentMetadata): Promise<any> {
if (this.validationOptions) {
this.validate(value, this.validationOptions);
}
return value;
}

protected validate(
object: any,
validationOptions: FileValidationOptions,
): any {
if (
validationOptions.maxFileSize &&
validationOptions.maxFileSize < object.size
) {
throw this.exceptionFactory(
`Validation failed (expected size is less ${validationOptions.maxFileSize})`,
);
}
if (
validationOptions.fileType &&
validationOptions.fileType !== object.mimetype
) {
throw this.exceptionFactory(
`Validation failed (expected file type is ${validationOptions.fileType})`,
);
}
return object;
}
Comment on lines +58 to +75
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@thiagomini thiagomini Jan 21, 2022 •
edited
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Altough this solution works for its intended purpose, I think it might be better to think of later needs for validation, or even consider the possibility of passing a custom validation function.

One suggestion is to handle it with Chain of Responsibility pattern, that way you achieve at same time the Open-Closed principle, allowing to extend the possible validations in the future, and also you could provide the user with the ability to define their own handlers to validate the file. I also like to implement chain of responsibility with a processor, which handles the execution of all handlers.

Example of handler interface:

export interface FileValidator {
    
   // This function determines if given handler should validate the incoming file. You could use it to check wether the option was given
   accepts(validationOptions: ValidationOptions): boolean
   
   // The return is a string because it is meant to be the reason of failure. if null, then validation passed
   validate(file: any, validationOptions: ValidationOptions): string
}

Example of handler:

export class FileSizeValidator implements FileValidator {
  accepts(validationOptions: ValidationOptions): boolean {
    return !!validationOptions.maxFileSize;
  }

  validate(file: any, validationOptions: ValidationOptions): any {
    if (file.size > validationOptions.maxFileSize) return `expected file type is ${validationOptions.fileType}`
  }

Example of processor:

export class FileValidationProcessor {
  constructor(private readonly validators: FileValidator[]) {
  }

  validateFile(file: any, validationOptions: ValidationOptions): string {
    const acceptingValidators = this.validators.filter(validator => validator.accepts(validationOptions))

    for (const validator of acceptingValidators) {
      const failedMessage = validator.validate(file, validationOptions);
      if (failedMessage) {
        return failedMessage
      }
    }
  }
}

Using the strategy above makes possible to add other validators without changing the already existing code (closed to changes).

}