@loopback/filter

@loopback/filter

A set of utility typings and filter builders to aid in constructing LoopBack filters using the builder pattern.

Overview

This lightweight module provides strongly-typed typings and filter builders to intuitively construct LoopBack filters to be used against querying a LoopBack filter-compatible server over the network or within the server itself.

Installation

{% include note.html content="Already installed @loopback/repository? Import from there instead. This package is meant for standalone use without @loopback/repository." %}

npm install --save @loopback/filter

Basic use

WhereBuilder

The WhereBuilder is a builder specifically meant to construct the where portion of the filter.

import {WhereBuilder} from '@loopback/filter';

const whereBuilder = new WhereBuilder();
const where = whereBuilder
  .between('price', 99, 299)
  .and({brand: 'LoopBack'}, {discount: {lt: 20}})
  .or({instock: true})
  .build();

FilterBuilder

The FilterBuilder is a builder to construct the filter as a whole.

import {FilterBuilder} from '@loopback/filter';

const filterBuilder = new FilterBuilder();
const filter = filterBuilder
  .fields('id', 'a', 'b')
  .limit(10)
  .offset(0)
  .order(['a ASC', 'b DESC'])
  .where({id: 1})
  .build();

FilterBuilder.where() also accepts an instance of WhereBuilder.

const filterBuilder = new FilterBuilder();
const filter = filterBuilder
  // ...
  .where(where)
  .build();

Advanced use

Strong typings

The FilterBuilder and WhereBuilder accept a model or any string-based key objects' typing for strong typings:

/**
 * Everything was imported from `@loopback/repository` as `@loopback/filter`
 * is re-exported in that package.
 **/
import {
  FilterBuilder,
  model,
  property,
  WhereBuilder,
} from '@loopback/repository';

@model()
class Todo extends Entity {
  @property({id: true})
  id: number;

  @property()
  title: string;

  @property()
  description: string;

  @property()
  priority: number;
}

const whereBuilder = new WhereBuilder<Todo>();
const where = whereBuilder.between('priority', 1, 3).build();

const filterBuilder = new FilterBuilder<Todo>();
const filter = filterBuilder
  .fields('id', 'title')
  .order(['title DESC'])
  .where(where)
  .build();

API docs

See the API docs for FilterBuilder and WhereBuilder for more details on the full API.

Contributions

• Guidelines
• Join the team

Tests

Run npm test from the root folder.

Contributors

See all contributors.

License

MIT