SQL Template Strings

!Dependencies
!Node Version

API Documentation

A simple yet powerful module to allow you to use ES6 tagged template strings for prepared/escaped statements.
Works with mysql, mysql2, postgres and sequelize.

Example for escaping queries (callbacks omitted):

``js
const SQL = require('sql-template-strings')

const book = 'harry potter'
const author = 'J. K. Rowling'

// mysql:
mysql.query('SELECT author FROM books WHERE name = ? AND author = ?', [book, author])
// is equivalent to
mysql.query(SQLSELECT author FROM books WHERE name = ${book} AND author = ${author})

// postgres:
pg.query('SELECT author FROM books WHERE name = $1 AND author = $2', [book, author])
// is equivalent to
pg.query(SQLSELECT author FROM books WHERE name = ${book} AND author = ${author})

// sequelize:
sequelize.query('SELECT author FROM books WHERE name = ? AND author = ?', {replacements: [book, author]})
// is equivalent to
sequelize.query(SQLSELECT author FROM books WHERE name = ${book} AND author = ${author})
`
This might not seem like a big deal, but when you do an INSERT with a lot columns writing all the placeholders becomes a nightmare:

`js
db.query(
'INSERT INTO books (name, author, isbn, category, recommended_age, pages, price) VALUES (?, ?, ?, ?, ?, ?, ?)',
[name, author, isbn, category, recommendedAge, pages, price]
)
// is better written as
db.query(SQL
INSERT
INTO books
(name, author, isbn, category, recommended_age, pages, price)
VALUES (${name}, ${author}, ${isbn}, ${category}, ${recommendedAge}, ${pages}, ${price})
)
`
Also template strings support line breaks, while normal strings do not.

How it works

The SQL template string tag transforms the template string and returns an _object_ that is understood by both mysql and postgres:

`js
const query = SQLSELECT author FROM books WHERE name = ${book} AND author = ${author}
typeof query // => 'object'
query.text // => 'SELECT author FROM books WHERE name = $1 AND author = $2'
query.sql // => 'SELECT author FROM books WHERE name = ? AND author = ?'
query.values // => ['harry potter', 'J. K. Rowling']
`

Building complex queries with append()


It is also possible to build queries by appending another query or a string with the append() method (returns this for chaining):

`js
query.append(SQLAND genre = ${genre}).append(' ORDER BY rating')
query.text // => 'SELECT author FROM books WHERE name = $1 AND author = $2 AND genre = $3 ORDER BY rating'
query.sql // => 'SELECT author FROM books WHERE name = ? AND author = ? AND genre = ? ORDER BY rating'
query.values // => ['harry potter', 'J. K. Rowling', 'Fantasy'] ORDER BY rating
`

This allows you to build complex queries without having to care about the placeholder index or the values array:

`js
const query = SQLSELECT * FROM books
if (params.name) {
query.append(SQL WHERE name = ${params.name})
}
query.append(SQL LIMIT 10 OFFSET ${params.offset || 0})
`

Raw values


Some values cannot be replaced by placeholders in prepared statements, like table names.
append() replaces the SQL.raw() syntax from version 1, just pass a string and it will get appended raw.

> Please note that when inserting raw values, you are responsible for quoting and escaping these values with proper escaping functions first if they come from user input (E.g. mysql.escapeId() and pg.escapeIdentifier()).
> Also, executing many prepared statements with changing raw values in a loop will quickly overflow the prepared statement buffer (and destroy their performance benefit), so be careful.

`js
const table = 'books'
const order = 'DESC'
const column = 'author'

db.query(SQLSELECT * FROM ".append(table).append(SQL" WHERE author = ${author} ORDER BY ${column} ).append(order))

// escape user input manually
mysql.query(SQLSELECT * FROM .append(mysql.escapeId(someUserInput)).append(SQL WHERE name = ${book} ORDER BY ${column} ).append(order))
pg.query(SQLSELECT * FROM .append(pg.escapeIdentifier(someUserInput)).append(SQL WHERE name = ${book} ORDER BY ${column} ).append(order)))
`

Prepared Statements in Postgres


Postgres requires prepared statements to be named, otherwise the parameters will be escaped and replaced on the client side.
You can set the name with the setName() method:

`js
// old way
pg.query({name: 'my_query', text: 'SELECT author FROM books WHERE name = $1', values: [book]})

// with template strings
pg.query(SQLSELECT author FROM books WHERE name = ${book}.setName('my_query'))
`
You can also set the name property on the statement object directly or use Object.assign().

Bound Statements in sequelize


By default, Sequelize will escape replacements on the client.
To switch to using a bound statement in Sequelize, call useBind().
The boolean parameter defaults to true.
Like all methods, returns this for chaining.
Please note that as long as the bound mode is active, the statement object only supports Sequelize, not the other drivers.

`js
// old way
sequelize.query('SELECT author FROM books WHERE name = ? AND author = ?', {bind: [book, author]})

// with template strings
sequelize.query(SQLSELECT author FROM books WHERE name = ${book}.useBind(true))
sequelize.query(SQLSELECT author FROM books WHERE name = ${book}.useBind()) // the same

// works with append (you can call useBind at any time)
const query = SQLSELECT * FROM books.useBind(true)
if (params.name) {
query.append(SQL WHERE name = ${params.name})
}
query.append(SQL LIMIT 10 OFFSET ${params.offset || 0})
`

Contributing


- Tests are written using mocha
- You can use npm test` to run the tests and check coding style
- Since this module is only compatible with ES6 versions of node anyway, use all the ES6 goodies
- Pull requests are welcome :)