Adding a raw select statement to the Knex query builder - node.js

Question

Using Knex to make queries to my Postgres DB. I have a function that provides a "base" query using the Knex QueryBuilder. This works fine until I need to add something raw to the SELECT statement. From what I can tell, running .raw always wants to return a result. I just need it to be added to the QueryBuilder, though, so it can be executed by a different part of my app.
const baseQuery = knex
.select(newUserFields)
.from('users')
.leftJoin('user_roles', 'users.id', 'user_roles.user_id')
.leftJoin('roles', 'user_roles.role_id', 'roles.id')
.leftJoin('role_permissions', 'roles.id', 'role_permissions.role_id')
.leftJoin(
'permissions',
'permissions.id',
'role_permissions.permission_id'
)
.groupBy(
'users.id',
'users.email',
'users.name',
'users.status',
'users.created_at',
'users.password_reset_expiration',
'users.password',
'users.password_reset_token'
)
.orderBy('users.created_at', 'desc');
I need to add the following to the select:
knex.raw('to_json(array_agg(distinct roles.name)) as roleNames')
knex.raw('to_json(array_agg(distinct permissions.name)) as permissionNames')
How can I add these raw selects to the base query so that the base query can then be passed to a different function as a QueryBuilder and added to?

Answer 1

The cool thing about knex is that it is a queryBuilder, which allows you to call the methods without any limits about the order of calls. That means that you can just construct your base query in a function, and then attach to it additional things (such as additional columns).
In your case you just can call another time to select (knex will join the select calls)
// base-query.js
export const getBaseQuery = () => knex
.select(newUserFields)
.from('users')
.leftJoin('user_roles', 'users.id', 'user_roles.user_id')
.leftJoin('roles', 'user_roles.role_id', 'roles.id')
.leftJoin('role_permissions', 'roles.id', 'role_permissions.role_id')
.leftJoin('permissions', 'permissions.id', 'role_permissions.permission_id')
.groupBy(
'users.id',
'users.email',
'users.name',
'users.status',
'users.created_at',
'users.password_reset_expiration',
'users.password',
'users.password_reset_token'
)
.orderBy('users.created_at', 'desc');
// other-file.js
import {getBaseQuery} from 'base-query';
const enhancedQuery = getBaseQuery().select([
knex.raw('to_json(array_agg(distinct roles.name)) as roleNames'),
knex.raw('to_json(array_agg(distinct permissions.name)) as permissionNames'),
]);
const results = await enhancedQuery;
Another cool way that I'm using heavily, solves the following requirement: Sometimes I need to change an internal query from the outside, I use the modify
For example, I have a getProducts method which execute a select query and do some data transformation.
In order to implement getProductById which needs to return the same data structure (it is just need to filter the base query) I pass a queryModifier method which modifies the original query.
async function getProducts(queryModifier) {
const products = await knex
.select('*')
.from('products')
.modify((queryBuilder) => {
if (typeof queryModifier === 'function') {
return queryModifier(queryBuilder);
}
});
return products.map(someDataTransformation);
}
async function getProductById(id) {
return getProducts((qb) => {
return qb.where('id', id);
});
}