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#Gatepost: Bind to Models From SQL

picture of fence with gate

Gatepost facilitates binding SQL statements to Model factories and instances, with the results cast as Model instance. With most ORMs have you model the database schema, but with Gatepost, you're not concerned with the database structure, only with what your queries return.

Gatepost uses VeryModel for Model factories and instances, giving you a lot of flexibility such as sharing your validation between your API and database, auto-converting values, etc.

Feel free to use knex, template strings, or other methods for generating your SQL. Gatepost is designed to stay out of your way.

'use strict';

const Gatepost = require('gatepost')('postgres://localhost/gatepost_test');
const SQL = require('sql-template-string'); //propery breaks out SQL template strings into a separate array to prevent SQL injection and errors

const Book = new Gatepost.Model({
  title: {
    validate: Joi.string()
  },
  id: {}
}, {
  cache: true,
  name: 'Book'
});

const knex = require('knex')({dialect: 'pg'});

//knex query builders are dealt with automatically
Book.fromSQL({
  name: 'getByCategory',
  sql: (args) => knex.select('id', 'title', 'author')
  .from('books').where({category: args.category})
});

Book.getByCategory({category: 'cheese'}).then(results) {
  results.forEach((book) => console.log(book.toJSON());
}).catch((err) => {
  console.log("error!!!!");
});

"use strict"

let SQL = require('sql-template-strings');
//sql-template-strings template tag returns a {text, values} object
//which gets turned into a prepare statement by gatepost

Book.fromSQL({
  name: 'insert',
  //using a template string
  sql: (args, model) => SQL`INSERT INTO books
(title, author, category)
VALUES (${model.title}, ${model.author}, ${model.category})
RETURNING id`,
  instance: true,
  oneResult: true
});

let book = Book.create({title: 'Ham and You', author: 'Nathan Fritz', category: 'ham'});

//using promises
book.insert()
.then((result) => console.log(`Book ID: ${book.id}`))
.catch((error) => console.log(`Gadzoons and error! ${error}`));

Model extensions

See VeryModel documentation for information on using gatepost.Models.

##Model options:

name: string used for naming the model
cache: boolean to refer to the model by string

Functions

fromSQL

Generate a Factory or Instance method from SQL for your Model

Arguments:

options: object

Options

name: string method name
sql: function returns the query object or string for pg.query or array of these.
oneResult: boolean only get one model intance or rejects with new gatepost.EmptyResult
instance: boolean Add the method to model instances rather than the factory.
model: Model or string cast the results into this model
validate: Joi Schema validate the args with this Joi Schema
validateOps: object Options passed to Joi.validate when validating arguments
validateModel: boolean True by default, instanced methods will validate the model (second arg) before running query.

Generated Method

function (args);

args: object unless oneArg set optional, the first argument passed to the sql function

returns Promise

Returned Promise

Calling a method generated from fromSQL returns a Promise which will then with the results, catch with a Postgres error from pg or gatepost.EmptyResult.

SQL Function

args: object arguments passed as the first option
model: Model for instances, the model instance that the function is called to

Examples

let knex = require('knex')({dialect: 'pg'});

//knex query builders are dealt with automatically
Book.fromSQL({
  name: 'getByCategory',
  sql: (args) => knex.select('id', 'title', 'author')
  .from('books').where({category: args.category})
});

Book.getByCategory({category: 'cheese'}).then(results) {
  results.forEach((book) => console.log(book.toJSON());
}).catch((err) => {
  //...
});

let SQL = require('sql-template-strings');

//sql-template-strings template tag returns a {text, values} object
//which gets turned into a prepare statement by gatepost
Book.fromSQL({
  name: 'insert',
  //using a template string
  sql: (args, model) => SQL`INSERT INTO books
(title, author, category)
VALUES (${model.title}, ${model.author}, ${model.category})
RETURNING id`,
  instance: true,
  oneResult: true
});

let book = Book.create({title: 'Ham and You', author: 'Nathan Fritz', category: 'ham'});

//using promises
book.insert()
.then((result) => console.log(`Book ID: ${book.id}`))
.catch((error) => console.log(`Gadzoons and error! ${error}`));