@talend/daikon-tql-client v1.3.1

Talend Daikon TQL Client

The goal of this library is to provide a NPM package that helps to convert javascript-style filters to TQL queries.

Installation

# yarn
yarn add @talend/daikon-tql-client

or

# npm
npm install @talend/daikon-tql-client --save

Usage

The package exposes a Query class used to create an instance on which you can chain operators and compositors in the wanted order before serialize it.

Basic example :

import { Query } from '@talend/daikon-tql-client';

const query = new Query();

query
	.equal('f1', 76)
	.or()
	.greaterThan('f2', 77);

query.serialize(); // -> '(f1 = 76) or (f2 > 77)'

Query

A Query is a serializable set of operators.\ It lets you stack operators and compositors one after an other by constantly returning the query reference.

import { Query } from '@talend/daikon-tql-client';

const query = new Query();

query
	.greaterThan('f2', 42)
	.and()
	.lessThan('f2', 76)
	.or()
	.equal('f2', 777);

query.serialize(); // -> '(f2 > 42) and (f2 < 76) or (f2 = 777)'

Hint: All the operators are accessible via the query instance in lower camel case.

Queries can be nested thanks to the nest() method without depth limit :

import { Query } from '@talend/daikon-tql-client';

const query = new Query();
const subQuery1 = new Query();
const subQuery2 = new Query();

subQuery1
	.equal('q2f1', 76)
	.or()
	.equal('q2f2', 77);

subQuery2
	.equal('q3f1', 78)
	.and()
	.equal('q3f2', 79);

query
	.greaterThan('f2', 42)
	.and()
	.nest(subQuery1) // <- !
	.and()
	.lessThan('f2', 666)
	.or()
	.nest(subQuery2) // <- !
	.or()
	.equal('f2', 777);

query.serialize();

Will produce :

(f2 > 42)  and (
	(q2f1 = 76)  or  (q2f2 = 77)
) and (f2 < 666)  or  (
	(q3f1 = 78) and (q3f2 = 79)
)  or  (f2 = 777)

Hint: Obviously, priority is conserved on nested queries

Queries can hold the negation of other queries or operators with the help of the not() method :

// query negation
import { Query } from '@talend/daikon-tql-client';

const query = new Query();
const subQuery = new Query();

subQuery
	.equal('q2f1', 76)
	.or()
	.equal('q2f2', 77);

query
	.greaterThan('f2', 42)
	.and()
	.not(subQuery) // <- !
	.and()
	.lessThan('f2', 666);

query.serialize(); // -> '(f2 > 42) and not((q2f1 = 76) or (q2f2 = 77)) and (f2 < 666)'

// operator negation
import { Query, Operators } from '@talend/daikon-tql-client';

const query = new Query();

query
	.equal('f1', 666)
	.or()
	.not(new Operators.Equal('f2', 777));

query.serialize(); // -> '(f1 = 666) or not((f2 = 777))'

Operator

The following operators are supported :

They are accessible via the Operators named export and can be serialized to TQL expressions :

import { Operators } from '@talend/daikon-tql-client';

const operator = new Operators.GreaterThan('col1', 42);

operator.serialize(); // -> 'col1 > 42'

Compositor

A Compositor is the only way to join operators in a query.

The following compositors are supported :

• and
• or

They can be used in the same way as an operator in a query :

import { Query } from '@talend/daikon-tql-client';

query
	.equal('f1', 666)
	.or()
	.equal('f2', 777);

query.serialize(); // -> '(f1 = 666) or (f2 = 777)'

Parser

The Parser class helps to transform a legacy Javascript-style filters tree to a serializable query :

import { Parser } from '@talend/daikon-tql-client';

const query = Parser.parse(myTree);
query.serialize();

An example of tree can be found in the tests.

How to create an operator ?

An Operator inherits from the Operator class (which "implements" the ISerializable interface). All operators are simple Javascript classes which have the Value and HasOperand properties exported.

To add your own operator, you just have to create a new class under src/converter/operators/.

For example, to create a new toto operator, create src/converter/operators/toto.js :

import Operator from './operator';

export default class Toto extends Operator {
	static value = 'is toto';
	static hasOperand = false;
}

And export it in src/converter/operators/index.js :

import Toto from './toto';
// ...

export {
	// ...,
	Toto,
};

Don't forget the associated tests ;)

Your new toto operator will be automatically available under Query :

import { Query } from '@talend/daikon-tql-client';

const query = new Query();

query
	.greaterThan('f1', 42)
	.and()
	.toto('f2');

query.serialize(); // -> '(f1 > 42) and (f2 is toto)'