power-filter

Filter objects in array by MongoDB-like FindOperation.

import { filter } from 'power-filter'
 
const objs = [
  { name: 'John' },
  { name: 'Naomi' },
  { name: 'Shin' },
]
 
const filteredObjs = filter(obj, { name: { $regex: /n$/ } })
assert.deepEqual(filteredObjs, [
  { name: 'John' },
  { name: 'Shin' },
])

Installation

npm install power-filter

Using types with flow

For Flow annotations, just use /jsnext entrypoint.

import { filter } from 'power-filter/jsnext'

All the interfaces are defined in the depending module mongolike-operations.

Concept

OAD: Operations As Data

Operations As Data(OAD) is the concept of handling large JSON data that all the data operations (update/find) should be written as JSON format (≒ plain object). This power-filter handles FindOperation as data.

In the previous example, { name: { $regex: /n$/ } } is the FindOperation.

The operation format is almost the same as MongoDB's Query Operators.

Here is another example using some more operators.

const filtered = filter(objs, {
  $or: [
    { age: { $gte: 20 } }, // $gte operator: age greater than or equal to 20
    { sex : { $eq: 'female' } }, // $eq operator: check equality
    { name : 'Naomi' }, // no operator stands for "$eq"
  ]
})

Phenyl Family

power-filter is one of Phenyl Family. Phenyl is a JavaScript Server/Client framework for State Synchronization over Environment(SSoE). FindOperation is used to fetch entities from the large JSON. In Phenyl framework power-filter is used for searching entities in local state and in mock server (phenyl-memory-db).

API Documentation

Definitions

const where = {
  { 'foo.bar[0].baz': { $eq: 123 } }
}

• where value is FindOperation.
• foo.bar[0].baz is DocumentPath.
• { $eq: 123 } is QueryCondition.
• $eq is QueryOperatorName.
• 123 is Operand.

FindOperation

Operation to find values.

type FindOperation =
  SimpleFindOperation |
  {| $and: Array<FindOperation> |} |
  {| $nor: Array<FindOperation> |} |
  {| $or: Array<FindOperation> |}
 
type SimpleFindOperation = {
  [fieldName: DocumentPath]: QueryCondition | EqCondition,
}
 
type EqCondition = Object | Array<Basic> | string | number | boolean
// QueryCondition: See below section
 

Example:

const findOperation = {
  $and: [
    { libraryName: 'phenyl' },
    { 'libraryVersion.major': { $gte: 1 } }
  ]
}

QueryCondition

Condition to find values, included in FindOperation. Almost compatible with MongoDB's Query Operators.

interface QueryCondition {
  // comparison
  $eq?: any,
  $gt?: any,
  $gte?: any,
  $in?: Array<any>,
  $lt?: any,
  $lte?: any,
  $ne?: any,
  $nin?: Array<any>,
  // logical
  $not?: QueryCondition,
  // element
  $exists?: boolean,
  $type?: BSONTypeNumber | BSONTypeString,
  // evaluation
  $mod?: [number, number],
  $regex?: RegExp | string,
  $options?: RegExp$flags,
  $text?: TextQueryCondition,
  $where?: Function, // To Be Implemented
  // geospatial
  $geoIntersects?: Object, // To Be Implemented
  $geoWithin?: Object, // To Be Implemented
  $near?: Object, // To Be Implemented
  $nearSphere?: Object, // To Be Implemented
  // array
  $all?: Array<any>,
  $elemMatch?: QueryCondition,
  $size?: number,
  // bitwise
  $bitsAllClear?: number, // Currently, only number is allowed
  $bitsAllSet?: number, // Currently, only number is allowed
  $bitsAnyClear?: number, // Currently, only number is allowed
  $bitsAnySet?: number, // Currently, only number is allowed
  // comments
  // $comment: // No implementation
}

DocumentPath

The same definition as Amazon DynamoDB's DocumentPath.

DocumentPath expresses nested value location.

{ foo: { arr: [ { bar: 'baz' }] }}

The string 'baz' is expressed as 'foo.arr[0].bar' in DocumentPath format.

This DocumentPath is slightly different from Dot Notation in MongoDB which expresses 'baz' as 'foo.arr.0.bar' (array index expression is different).

filter()

Filter values matching the given FindOperation.

filter(
  objs: Array<Object>,
  where: FindOperation
): Array<Object>
 

Parameters

objs

Array of objects to be searched.

import { filter } from 'power-filter'
const objs = [
  { foo: 1, bar: 1 }, { foo: 2, bar: 1 }, { foo: 3, bar: 1 }
]
const filtered = assign(objs, { foo: 3 })
assert.deepEqual(filtered, [{ foo: 3, bar: 1 }])
assert(objs[2] === filtered[0]) // Filtered value are references, not copy.

where

FindOperation. See its definition above.

Query Operators

Almost the same as MongoDB's Query Operators.

$eq

Matches values that are equal to a specified value.

const objs = [ { a: 1, b: 2 }, { a: 100, b: 200 }]
assert.deepEqual(filter(objs, { a: { $eq: 100 } }), [{ a: 100, b: 200 }])

$eq operator can be omitted.

const objs = [ { a: 1, b: 2 }, { a: 100, b: 200 }]
assert.deepEqual(filter(objs, { a: 100 }), [{ a: 100, b: 200 }])

$gt

Matches values that are greater than a specified value.

const objs = [ { a: 1, b: 2 }, { a: 100, b: 200 }]
assert.deepEqual(filter(objs, { a: { $gt: 1 } }), [{ a: 100, b: 200 }])

$gte

Matches values that are greater than or equal to a specified value.

const objs = [ { a: 1, b: 2 }, { a: 100, b: 200 }]
assert.deepEqual(filter(objs, { a: { $gte: 1 } }), [{ a: 1, b: 2 }, { a: 100, b: 200 }])

$in

Matches any of the values specified in an array.

const objs = [ { a: 1, b: 2 }, { a: 100, b: 200 }]
assert.deepEqual(filter(objs, { a: { $in: [1, 2, 3] } }), [{ a: 1, b: 2 }])

$lt

Matches values that are less than a specified value.

const objs = [ { a: 1, b: 2 }, { a: 100, b: 200 }]
assert.deepEqual(filter(objs, { a: { $lt: 1 } }), [])

$lte

Matches values that are less than or equal to a specified value.

const objs = [ { a: 1, b: 2 }, { a: 100, b: 200 }]
assert.deepEqual(filter(objs, { a: { $lte: 1 } }), [{ a: 1, b: 2 }])

$ne

Matches all values that are not equal to a specified value.

$nin

Matches none of the values specified in an array.

$not

Joins query clauses with a logical AND returns all objects that match the conditions of both clauses.

$exists

Matches objects that have the specified field.

$type

Selects objects if a field is of the specified type.

$mod

Performs a modulo operation on the value of a field and selects objects with a specified result.

$regex

Selects objects where values match a specified regular expression.

$options

$text

Performs text search.

$where

Matches objects that satisfy a JavaScript matcher function.

$all

Matches arrays that contain all elements specified in the query.

$elemMatch

Selects objects if element in the array field matches all the specified $elemMatch conditions.

$size

Selects documents if the array field is a specified size.

LICENSE

Apache License 2.0