AOP Decorators

The module contain decorators that help us to apply Aspect Oriented Programming (AOP) into NodeJs project. It uses Winston as based logger

Notes:

- It will process from top to bottom.

``Typescript
class SampleClass {
@IsString()
@Transform((x) => x.concat(' transformed'))
@Mapping('renamedFieldName')
@MaxStringSize(5)
private sampleProperty: boolean;
}

// The flow will be:
// - Validate isString
// - Transform data
// - Mapping field name
// - Validate String length
`

Table of Contents

- AOP Decorators
- Notes:
- Table of Contents
- Installation
- Usage
- Validator
- String
- Number
- Boolean
- Object
- Array
- Custom Test
- Transform
- Mapping
- LogContext
- LogInputParam
- Parameters
- CHANGELOG

Installation

`bash
npm install decorators-utils

or

yarn add decorators-utils
`

Usage

`Typescript
@logContext()
class SampleClass {
public logger: ILogger = new LoggerImpl();

@validate
@logInputParams()
public sampleMethod(@required() _params: any): any {
this.logger.info('dummy message');
}
}
`

Validator

The module supports testing for string, number, boolean ,object, array, and Test to support custom Test

$3

Possible options for String: IsEmail, IsMatched, IsString, MaxStringSize, MinStringSize

`Typescript
//Define class schema
class SampleClass {
@IsString()
@IsMatched(/^dog/)
@IsEmail()
@MaxStringSize(5)
@MinStringSize(1)
private sampleProperty: string;
}

//Run function to validate data based on the schema above
validateSchema(SampleClass, { sampleProperty: 'sample' });

//Sample returned error
{
message: 'sampleProperty must be string',
name: 'IS_STRING',
path: 'sampleProperty',
}
`

$3

Possible options for String: IsLarger, IsLess, IsNumber, MaxDigits, MinDigits

`Typescript
//Define class schema
class SampleClass {
@IsLarger(2)
@IsLess(5)
@IsNumber()
@MaxDigits(3)
@MinDigits(1)
private sampleProperty: number;
}

//Run function to validate data based on the schema above
validateSchema(SampleClass, { sampleProperty: 123 });

//Sample returned error
{
message: 'sampleProperty must be number',
name: 'IS_NUMBER',
path: 'sampleProperty',
}
`

$3

Possible options for String: IsBoolean

`Typescript
//Define class schema
class SampleClass {
@IsBoolean()
private sampleProperty: boolean;
}

//Run function to validate data based on the schema above
validateSchema(SampleClass, { sampleProperty: true });

//Sample returned error
{
message: 'sampleProperty must be boolean',
name: 'IS_BOOLEAN',
path: 'sampleProperty',
}
`

$3

Possible options for String: IsValidObject

`Typescript
//Define class schema
class ChildClass {
@IsString()
private requestId: string
}

class SampleClass {
@IsValidObject()
private sampleProperty: ChildClass;
}

//Run function to validate data based on the schema above
validateSchema(SampleClass, { sampleProperty: { requestId:'string' } });

//Sample returned error
{
message: 'requestId must be string',
name: 'IS_VALID_OBJECT',
path: 'sampleProperty.requestId',
}
`

$3

Possible options for String: IsValidArray, ArraySize

`Typescript
//Define class schema
class ChildClass {
@IsString()
private requestId: string
}

class SampleClass {
@IsValidArray(ChildClass)
private sampleProperty: ChildClass[];
}

class SampleClass {
@IsValidArray(String)
private sampleProperty: String[];
}

class SampleClass {
@IsValidArray(Number)
private sampleProperty: Number[];
}

class SampleClass {
@IsValidArray(Boolean)
private sampleProperty: Boolean[];
}

//Run function to validate data based on the schema above
validateSchema(SampleClass, { sampleProperty: [{ requestId:'string' }] });

//Sample returned error
{
message: 'must be a valid array element',
name: 'IS_VALID_ARRAY',
path: 'sampleProperty[2]',
};
`

`Typescript
class SampleClass {
@ArraySize({ max: 2, min: 1 })
private sampleProperty: Boolean[];
}

//Run function to validate data based on the schema above
validateSchema(SampleClass, { sampleProperty: [{ requestId:'string' }] });

//Sample returned error
{
message: 'sampleProperty size must be less than 2, greater than 1',
name: 'IS_VALID_ARRAY',
path: 'sampleProperty',
};
`

$3

`Typescript
//Define class schema
const canConvertStringToNum = (value: string): boolean => {
return !!parseInt(value);
};

class SampleClass {
@Test(canConvertStringToNum)
private sampleProperty: string;

public getData(): void {
console.log(this.sampleProperty);
}
}

//Run function to validate data based on the schema above
validateSchema(SampleClass, { sampleProperty: '123' });

//Sample returned error
{
message: 'sampleProperty custom test failed',
name: 'canConvertStringToNum',
path: 'sampleProperty',
};
`

Transform

modify the input data

`Typescript
//Define class schema
class SampleClass {
@Transform((x) => x.concat(' transformed'))
private sampleProperty: boolean;
}

//Run function to validate data based on the schema above
const data = { sampleProperty: 'sampleData' }
validateSchema(SampleClass, data);

//New data
console.log(data.sampleProperty) // => sampleData transformed
`

Mapping

Change field name

`Typescript
//Define class schema
class SampleClass {
@Mapping('renamedFieldName')
private sampleProperty: boolean;
}

//Run function to validate data based on the schema above
const data = { sampleProperty: 'sampleData' }
validateSchema(SampleClass, data);

//New data
console.log(data.renamedFieldName) // => sampleData transformed
`

LogContext

`Typescript
@logContext()
class SampleClass {
public logger: ILogger = new LoggerImpl();

public sampleMethod(_params: any): any {
this.logger.info('dummy message');
}
}
`

The message will be [SampleClass] [sampleMethod] dummy message

LogInputParam

`Typescript
class SampleClass {
public logger: ILogger = new LoggerImpl();

@logInputParams()
public sampleMethod(_params: any): any {
this.logger.info('dummy message');
}
}
`

When the method is called, an additional log record will appear method is called with param with the input param value

Parameters

`Typescript
class SampleClass {
public logger: ILogger = new LoggerImpl();

@validate
public sampleMethod(@required() _params: any): any {}
}
`

Although _params is a required parameters, it still accept undefined value.
It will throw error when @required(error), or even return boolean value (true/false) by @required(false)`

CHANGELOG

CHANGELOG