@neuralegion/class-sanitizer

neuralegion/class-sanitizer

Allows to use decorator and non-decorator based sanitization in your Typescript classes. Internally uses validator.js and Caja-HTML-Sanitizer to make sanitization.

Table of Contents

• Installation
• Usage
  • Sanitizing arrays
  • Sanitizing sets
  • Sanitizing maps
  • Sanitizing nested objects
  • Inheriting sanitization decorators
  • Custom sanitization classes
  • Using service container
  • Manual sanitization
  • Sanitization decorators
• Examples

Installation

npm install @neuralegion/class-sanitizer --save

Usage

Create your class and put some sanity decorators on its properties you want to sanitize:

import { sanitize, Trim, Rtrim, Blacklist } from '@neuralegion/class-sanitizer';

export class Post {
  @Trim()
  public title!: string;

  @Rtrim(['.'])
  @Blacklist(/(1-9)/)
  public text!: string;
}

let post1 = new Post();
post1.title = ' Hello world ';
post1.text = '1. this is a great (2) post about hello 3 world.';

sanitize(post);
console.log(post);
// now post will look like this:
// Post {
// title: "Hello world",
// text: ". this is a great  post about hello  world"
// }

Sanitizing arrays

If your field is an array and you want to perform sanitization of each item in the array you must specify a special each: true decorator option:

import { Escape } from '@neuralegion/class-sanitizer';

export class Post {
  @Escape({
    each: true
  })
  public tags!: string[];
}

This will sanitize each item in post.tags array.

Sanitizing sets

If your field is an array and you want to perform sanitization of each item in the set you must specify a special each: true decorator option:

import { Escape } from '@neuralegion/class-sanitizer';

export class Post {
  @Escape({
    each: true
  })
  public tags!: Set<string>;
}

This will sanitize each item in post.tags set.

Sanitizing maps

If your field is an array and you want to perform sanitization of each item in the map you must specify a special each: true decorator option:

import { Escape } from '@neuralegion/class-sanitizer';

export class Post {
  @Escape({
    each: true
  })
  public tags!: Map<string, string>;
}

This will sanitize each item in post.tags map.

Sanitizing nested objects

If your object contains nested objects and you want the sanitizer to perform their sanitization too, then you need to use the @SanitizeNested() decorator:

import { SanitizeNested } from '@neuralegion/class-sanitizer';

export class Post {
  @SanitizeNested()
  public user!: User;
}

Inheriting sanitization decorators

When you define a subclass which extends from another one, the subclass will automatically inherit the parent's decorators. If a property is redefined in the descendant class decorators will be applied on it both from that and the base class.

import {
  sanitize,
  Blacklist,
  NormalizeEmail,
  ToString,
  Escape
} from '@neuralegion/class-sanitizer';

class BaseContent {
  @NormalizeEmail()
  public email!: string;

  @ToString()
  public password!: string;
}

class User extends BaseContent {
  @Escape()
  public name!: string;

  @Blacklist(/(1-9)/)
  public password!: string;
}

let user = new User();

user.email = '[e-mail]'; // inherited property
user.password = 'password'; // password wil be perform not only ToString, but Blacklist as well
user.name = 'Name <a href="/"></a>';

sanitize(user);

Custom sanitization classes

If you have custom sanity logic you want to use as annotations you can do it this way:

1. First create a file, lets say LetterReplacer.ts, and create there a new class:

   import {
     SanitizerInterface,
     SanitizerConstraint
   } from '@neuralegion/class-sanitizer';
   
   @SanitizerConstraint()
   export class LetterReplacer implements SanitizerInterface {
     public sanitize(text: string): string {
       return text.replace(/o/g, 'w');
     }
   }
   

   Your class must implement SanitizerInterface interface and its sanitize method, which defines sanitization logic.

2. Then you can use your new sanitization constraint in your class:

   import { Sanitize } from '@neuralegion/class-sanitizer';
   import { LetterReplacer } from './LetterReplacer';
   
   export class Post {
     @Sanitize(LetterReplacer)
     public title!: string;
   }
   

   Here we set our newly created LetterReplacer sanitization constraint for Post.title.

3. Now you can use sanitizer as usual:

   import { sanitize } from '@neuralegion/class-sanitizer';
   
   sanitize(post);
   

Using service container

Sanitizer supports service container in the case if want to inject dependencies into your custom sanity constraint classes. Here is example how to integrate it with typedi:

import { Container } from 'typedi';
import { useContainer, Sanitizer } from '@neuralegion/class-sanitizer';

// do this somewhere in the global application level:
useContainer(Container);
let sanitizer = Container.get(Sanitizer);

// now everywhere you can inject Sanitizer class which will go from the container
// also you can inject classes using constructor injection into your custom SanitizerConstraint-s

Manual sanitization

There are several methods in the Sanitizer that allows to perform non-decorator based sanitization:

import Sanitizer from '@neuralegion/class-sanitizer';

Sanitizer.blacklist(str, chars);
Sanitizer.escape(str);
Sanitizer.secure(str);
Sanitizer.ltrim(str, chars);
Sanitizer.normalizeEmail(str, isLowercase);
Sanitizer.rtrim(str, chars);
Sanitizer.stripLow(str, keepNewLines);
Sanitizer.toBoolean(input, isStrict);
Sanitizer.toDate(input);
Sanitizer.toFloat(input);
Sanitizer.toInt(input, radix);
Sanitizer.toString(input);
Sanitizer.trim(str, chars);
Sanitizer.whitelist(str, chars);
Sanitizer.toUpperCase(str);
Sanitizer.toLowerCase(str);

Sanitization decorators

Decorator	Description
@Blacklist(chars: RegExp)	Remove characters that appear in the blacklist.
@Escape()	Replace <, >, &, ', " and / with HTML entities.
@Secure()	Strips unsafe tags and attributes from html.
@Ltrim()	Trim characters from the left-side of the input.
@NormalizeEmail()	Canonicalize an email address.
@Rtrim()	Trim characters from the right-side of the input.
@StripLow()	Remove characters with a numerical value < 32 and 127, mostly control characters.
@ToBoolean(isStrict?: boolean)	Convert the input to a boolean. Everything except for '0', 'false' and '' returns true. In strict mode only '1' and 'true' return true.
@ToDate()	Convert the input to a date, or null if the input is not a date.
@ToFloat()	Convert the input to a float.
@ToInt()	Convert the input to an integer, or NaN if the input is not an integer.
@ToString()	Convert the input to a string.
@Trim(chars?: string[])	Trim characters (whitespace by default) from both sides of the input. You can specify chars that should be trimmed.
@Whitelist(chars: RegExp)	Remove characters that do not appear in the whitelist.* The characters are used in a RegExp and so you will need to escape some chars, e.g. whitelist(input, '\[\]').
@ToUpperCase()	(self-explanatory)
@ToLowerCase()	(self-explanatory)

Examples

Take a look at the tests for more examples of usages.