Query Strings Parser

Middleware to transform query strings in a format that is recognized by the MongoDB, MySQL¹and other databases.

Prerequisites

To ensure the smooth operation of the middleware, your web application must be built using theexpress.jsorhapi.jsframeworks.

Installing

Use the npm command to install this library into your project:

npm i query-strings-parser --save

Usage Examples

constexpress=require('express')
constqs=require('query-strings-parser')
constapp=express()

app.use(qs())// middleware query-strings-parser

app.listen(3000,(req,res)=>{
console.log('app listening on port 3000')
})

app.get('/',(req,res)=>{
res.send('the query is:'+JSON.stringify(req.query))
})

/**
* Request: http://localhost:3000?fields=name,age&skip=10&limit=10&sort=created_at
* Result (req.query):
* {
* fields: { name: 1, age: 1 },
* sort: { created_at: 1 }
* filters: {},
* pagination: {
* skip: 10,
* limit: 10
* },
* original: '?fields=name,age&skip=10&limit=10&sort=created_at'
* }
*/

Using custom configurations:

constexpress=require('express')
constqs=require('query-strings-parser')
constapp=express()

app.use(qs({
use_page:true,
client_db:'mongodb',
date_field:{
start_at:'timestamp',
end_at:'timestamp'
},
default:{
fields:{name:1,age:1,number:1,_id:0},
sort:{created_at:-1},
filters:{},
pagination:{
page:1,
limit:100
}
}
}))

/**
* Request: http://localhost:3000?fields=name,age&age=30
* Result (req.query):
* {
* fields: { name: 1, age: 1},
* sort: { created_at: -1 }
* filters: {age: 30},
* pagination: {
* limit: 100,
* page: 1
* },
* original: '?fields=name,age&age=30'
* }
*/

The middleware uses the following defaults:

options={
use_page:false,
client_db:'mongodb',
date_field:{
start_at:'created_at',
end_at:'created_at'
},
default:{
fields:{},
sort:{},
filters:{},
pagination:{
limit:Number.MAX_SAFE_INTEGER,
skip:0,
page:1
}
}
}

If the options are not provided, the default values will be used for the treatment of queries strings.

For more details, access thewikipage.

Parsers Functions

To use these functions, simply call them through the middleware instance and pass them the query string to be converted and its default values. If you pass the default values ​​a merge will be performed with the result of the query strings. Here are some examples of each analyzer:

• parser()

constqs=require('query-strings-parser')

constquery='?fields=name,age&page=1&limit=10&sort=created_at'
console.log(qs.parseFields(query,{},{use_page:true}))

/**
* Result:
* {
* fields: { name: 1, age: 1 },
* sort: { created_at: 1 },
* filters: {},
* pagination: { limit: 10, page: 1 },
* original: '?fields=name,age&page=1&limit=10&sort=created_at'
* }
*/

For moredetails >>

• parseFields()

constqs=require('query-strings-parser')

constquery='?fields=name,age'
console.log(qs.parseFields(query))

/**
* Result:
* {
* name: 1,
* age: 1
* }
*/

For moredetails >>

• parseSort()

constqs=require('query-strings-parser')

constquery='?sort=name,-age,created_at'
console.log(qs.parseSort(query))

/**
* Result:
* {
* name: 1,
* age: -1,
* created_at: 1
* }
*/

For moredetails >>

• parsePagination()

constqs=require('query-strings-parser')

constquery='?limit=20&page=3'
console.log(qs.parsePagination(query,{},true))

/**
* Result:
* {
* limit: 20,
* page: 3
* }
*/

For moredetails >>

• parseFilter()

constqs=require('query-strings-parser')

constquery='?name=elvis&age=80'
console.log(qs.parseFilter(query))

/**
* Result:
* {
* name: 'elvis',
* age: 80
* }
*/

For moredetails >>

• parseDate()

constqs=require('query-strings-parser')

constquery='?start_at=2019-02-05T00:00:00&end_at=2019-02-05T23:59:59'
console.log(qs.parseDate(query))

/**
* Result:
* {
* $and: [
* { created_at: { lt: 2019-02-05T23:59:59 }},
* { created_at: { gte: 2019-02-05T00:00:00 }}
* ]}
* }
*/

For moredetails >>

Supported Query Strings

For informations and details about the supported query strings, access thewikipage.

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Future Features

• ¹Support for relational databases such as MySQL, PostgreSQL and SQLite.