es6 template literals example

01_test.js

import pgquery from 'pgquery'

const role = 'admin'
const likes = 5

console.log(pgquery`
  SELECT * FROM users WHERE role = ${role} AND likes > ${likes}
`)
/*
{ queryString: '\n  SELECT * FROM users WHERE role = $1::varchar AND likes > $2::int\n',
  params: [ 'admin', 5 ] }
*/

02_pgquery.js

export default function pgquery(parts, ...params) {
  const queryString = parts.reduce((acc, part, index) => {
    const param = params[index - 1]
    let type

    if (typeof param === 'string') {
      type = 'varchar'
    } else if (typeof param === 'number') {
      type = 'int'
    } else {
      throw new Error('Unsupported param')
    }

    return acc + `\$${index}::${type}` + part
  })

  return {
    queryString,
    params,
  }
}