Utilities and express middleware for parsing parameters

This module contains some helper class and utilities for simplifying the task of parsing "parameters" both in express based applications as well as in other code parts.

The library may be added to any project with the following command:

# npm install @yeasoft/parseutils

NOTICE

Heavy work in progress. Most of the documentation is currently
only available in the corresponding .d.ts files

Learning by example

Since the module is in a very early stage, there is no real documentation. Here some examples:

A simple parser for Objects

const { ParamParser, HttpStatusError, resultHelper } = require( "@yeasoft/parseutils" );
const { getSpecifiedStr } = require( "@yeasoft/baseutils" );

function test( name, result, expect ) {
    if ( result.error instanceof Error ) {
        expect ? console.error( `${name} failed with error ${result.error.status}:`, result.error ) : console.log( `${name} passed with expected error ${result.error.status}: ${result.error.message}` );
    }
    else {
        expect ? console.log( `${name} passed:`, result ) : console.error( `${name} failed with unexpected result:`, result );
    }
}

const parser = new ParamParser( { errormode: 'param' } );

// add standard email address validator for parameters "from", "to", "cc" and "bcc
parser.setValidator( "from,to,cc,bcc", "email" );
// add your own validator for parameters "subject", "text" and "html"
parser.setValidator( "subject,text,html", ( params, property ) => {
    if ( typeof params[ property ] === 'string' ) {
        let subject = params[ property ].toLowerCase();
        if ( [ 'fuck', 'cunt', 'motherfucker' ].some( explicitWord => subject.indexOf( explicitWord ) != -1 ) ) {
            throw new HttpStatusError( "Mind your language", 451 );
        }
    }
} );
// add standard lowerize transformer for email fields
parser.setTransformer( "from,to,cc,bcc", "lower" );
// add your own transformer that makes sure you have a subject
parser.setTransformer( "subject", ( params, property ) => { params[ property ] = getSpecifiedStr( params[ property ], "No Subject" ); } );

// create a parser that returns all parameters but requires "from" to" and "subject" to be specified. "subject" will by autogenerated by the supplied tranformer.
const parseAll = parser.allParser( "from,to,subject" );
test( "Test 1", parseAll( {} ) );
test( "Test 2", parseAll( { from: "[email protected]", subject: "Yeah!" } ) );
test( "Test 3", parseAll( { from: "[email protected]", to: "Yeah!" } ) );
test( "Test 4", parseAll( { from: "[email protected]", to: "[email protected]", subject: "Fuck you!" } ) );
test( "Test 5", parseAll( { from: "[email protected]", to: "[email protected]" } ), true );

// create a parser that returns onöy the specified parameters but requires "from" and "to" to be specified.
const parseOnly = parser.onlyParser( "from!,to!,cc,bcc,subject" );
test( "Test 6", parseOnly( {} ) );
test( "Test 7", parseOnly( { from: "[email protected]", subject: "Yeah!" } ) );
test( "Test 8", parseOnly( { from: "[email protected]", to: "Yeah!" } ) );
test( "Test 9", parseOnly( { from: "[email protected]", to: "[email protected]", subject: "Fuck you!" } ) );
test( "Test 10", parseOnly( { from: "[email protected]", to: "[email protected]" } ), true );

A simple parser for express

See how simple it is to implement a web api:

const { ParamParser, HttpStatusError } = require( "@yeasoft/parseutils" );
const { getSpecifiedStr } = require( "@yeasoft/baseutils" );

const emailParser = new ParamParser( { methods: "GET,POST", errormode: 'exception' } );

// add standard email address validator for parameters "from", "to", "cc" and "bcc
parser.setValidator( "from,to,cc,bcc", "email" );
// add your own validator
parser.setValidator( "subject,text,html", ( params, property ) => {
    if ( typeof params[ property ] === 'string' ) {
        let subject = params[ property ].toLowerCase();
        if ( [ 'fuck', 'cunt', 'motherfucker' ].some( explicitWord => subject.indexOf( explicitWord ) != -1 ) ) {
            throw new HttpStatusError( "Mind your language", 451 );
        }
    }
} );
// add standard lowerize transformer for email fields
parser.setTransformer( "from,to,cc,bcc", "lower" );
// add your own transformer that makes sure you have a subject
parser.setTransformer( "subject", ( params, property ) => { params[ property ] = getSpecifiedStr( params[ property ], "No Subject" ); } );



// register routes for sending mails
httpd.all( [ 'api/send/:from/:to/:subject', 'api/send' ], parser.only(), ( req, res ) => {
    // you do have to care on parameter errors -> the parser throws an exception and everything is done by express

    // regardless of the method and way of passing the parameters (url, query params, body): everything is in req.params
    sendMyMail( req.params, ( error, result ) => {
        resultHelper.handle( req, res, error, result, 200 );
    } );
} );