KnexNest

Takes a Knex.js select query object and hydarates a list of nested objects using the NestHydration npm module.

This can be simply accomplished without this library by doing

return knex.select(...)
    .then(NestHydrationJS.nest)
    .then(function (data) {
        ...
    })
;

However Postgres limits column names to 63 characters and this becomes a problem when trying to nest objects several deep using NestHydration. A column name such as _activeUser_purchases__product_originalManufacturer_logoSmall_url would be too long and would cause nasty behavior. This module handles this problem by mapping long names to shorter ones and then returning them with a structPropToColumnMap object passed to NestHydration.

Example Usage

var Knex = require('knex');
var knexnest = require('knexnest');
 
var knex = Knex({
    client: 'postgres',
    connection: process.env.DATABASE_URL
});
 
var sql = knex
    .select(
        'c.id    AS _id',
        'c.title AS _title',
        't.id    AS _teacher_id',
        't.name  AS _teacher_name',
        'l.id    AS _lesson__id',
        'l.title AS _lesson__title'
    )
    .from('course AS c')
    .innerJoin('teacher AS t', 't.id', 'c.teacher_id')
    .innerJoin('course_lesson AS cl', 'cl.course_id', 'c.id')
    .innerJoin('lesson AS l', 'l.id', 'cl.lesson_id')
;
knexnest(sql).then(function (data) {
    result = data;
});
/* result should be like:
[
    {id: '1', title: 'Tabular to Objects', teacher: {id: '1', name: 'David'}, lesson: [
        {id: '1', title: 'Defintions'},
        {id: '2', title: 'Table Data'},
        {id: '3', title: 'Objects'}
    ]},
    {id: '2', title: 'Column Names Define Structure', teacher: {id: '2', name: 'Chris'}, lesson: [
        {id: '4', title: 'Column Names'},
        {id: '2', title: 'Table Data'},
        {id: '3', title: 'Objects'}
    ]},
    {id: '3', title: 'Object On Bottom', teacher: {id: '1', name: 'David'}, lesson: [
        {id: '5', title: 'Non Array Input'},
    ]}
]
*/

Related Projects

• NestHydrationJS : The base project