LinqQs-JS

LINQ Query Syntax for javascript.

What ?

from`s in ${students} order by s.age descending, s.name select s.name`

This was correct JS syntax and now has a meaningful value.

Differences with C# linq

First, everything is in a "string" definition, so it's not compiled but interpreted at run-time. Pure code can appear in ${...} and the in-string code is JS code - so we don't enjoy such strong typing (yet?)

Function names are re-cased - ie., camelCase is used instead of PascalCase

How ?

This JS syntax :

prefix`someString ${someValue} andSoOn`

allows the function prefix to receive these arguments :

• The string fragments (here: "someString " and " andSoOn")
• The values given (here someValue) without going through the string process - the received value is directly the object

The linq parser is therefore a parser going through these two lists at the same time.

JS parsing

No, the library does not necessarily parse JS. It certainly parses linq keywords to delimitate what might be JS code and use new Function giving it code directly.

The functions might be either executed (ex. MemCollection) or parsed (ex. SqlCollection) depending on how to use it

Stages

• 1: Collect of panties (Take the string fragments and arguments and create a list of Transformations along a selection) - Occurs on from``...`` call
• 2: ? (it depends on the LinqCollection implementation used) - Occurs on iterating the result (SQL query, in-memory sorting/filtering/&c., ...)
• 3: Profit

Implemented functionalities

The implementations (in-memory/sql) are done in the collection.

function firstOf(LinqCollection<T> c) {
	return from`x in ${c} where x... select x...`.first()
}

The behavior of calling firstOf (filter/sql call/...) will be determined by the class of c

Usage

Collection creation

interface Student {
	name: string
	age: number
}

In-memory

@linxjs/mem provides memCollection<T>(data: Iterable<T> | AsyncIterable<T>) that allows to provide data directly

import memCollection from '@linxjs/mem'

const students = memCollection<Student>([
	{ name: 'John', age: 21 },
	{ name: 'Melissa', age: 20 }
])

Sql

@linx/sql uses knex to specify a database.

import knex from 'knex'
import sqlCollection from '@linxjs/sql'

const db = knex(dbConfig)
const students = sqlCollection<Student>(db, 'students')