Safe SQL Template Tag

Provides a string template tag that makes it easy to compose MySQL and PostgreSQL query strings from untrusted inputs by escaping dynamic values based on the context in which they appear.

• Installation
• Supported Databases
• Usage By Example
  • mysql returns a SqlFragment
  • No excess quotes
  • Escaped backticks delimit SQL identifiers
  • Escape Sequences are Raw
• API
  • mysql(options)
  • pgsql(options)
  • mysql`...`
  • pg`...`
  • SqlFragment
  • SqlId

Installation

$ npm install safesql

Supported Databases

MySQL via

const { mysql } = require('safesql');

PostgreSQL via

const { pg } = require('safesql');

Usage By Example

const { mysql, SqlId } = require('safesql');

const table = 'table';
const ids = [ 'x', 'y', 'z' ];
const str = 'foo\'"bar';

const query = mysql`SELECT * FROM \`${ table }\` WHERE id IN (${ ids }) AND s=${ str }`;

console.log(query);
// SELECT * FROM `table` WHERE id IN ('x', 'y', 'z') AND s='foo''"bar'

mysql functions as a template tag.

Commas separate elements of arrays in the output.

mysql treats a ${...} between backticks (\`) as a SQL identifier.

A ${...} outside any quotes will be escaped and wrapped in appropriate quotes if necessary.

---

PostgreSQL differs from MySQL in important ways. Use pg for Postgres.

const { pg, SqlId } = require('safesql');

const table = 'table';
const ids = [ 'x', 'y', 'z' ];
const str = 'foo\'"bar';

const query = pg`SELECT * FROM "${ table }" WHERE id IN (${ ids }) AND s=${ str }`;

console.log(query);
// SELECT * FROM "table" WHERE id IN ('x', 'y', 'z') AND s=e'foo''\"bar'

---

You can pass in an object to relate columns to values as in a SET clause above.

The output of mysql`...` has type SqlFragment so the NOW() function call is not re-escaped when used in ${data}.

const { mysql } = require('safesql');

const column  = 'users';
const userId  = 1;
const data    = {
  email:    '[email protected]',
  modified: mysql`NOW()`
};
const query = mysql`UPDATE \`${column}\` SET ${data} WHERE \`id\` = ${userId}`;

console.log(query);
// UPDATE `users` SET `email` = '[email protected]', `modified` = NOW() WHERE `id` = 1

mysql returns a SqlFragment

Since mysql returns a SqlFragment you can chain uses:

const { mysql } = require('safesql');

const data = { a: 1 };
const whereClause = mysql`WHERE ${data}`;
console.log(mysql`SELECT * FROM TABLE ${whereClause}`);
// SELECT * FROM TABLE WHERE `a` = 1

No excess quotes

An interpolation in a quoted string will not insert excess quotes:

const { mysql } = require('safesql')

console.log(mysql`SELECT '${ 'foo' }' `)
// SELECT 'foo'
console.log(mysql`SELECT ${ 'foo' } `)
// SELECT 'foo'

Escaped backticks delimit SQL identifiers

Backticks end a template tag, so you need to escape backticks.

const { mysql } = require('safesql')

console.log(mysql`SELECT \`${ 'id' }\` FROM \`TABLE\``)
// SELECT `id` FROM `TABLE`

Escape Sequences are Raw

Other escape sequences are raw.

const { mysql } = require('safesql')

console.log(mysql`SELECT "\n"`)
// SELECT "\n"

API

Assuming

const { mysql, pg, SqlFragment, SqlId } = require('safesql')

mysql(options)

pgsql(options)

When called with an options bundle instead of as a template tag, mysql and pg return a template tag that uses those options.

The options object can contain any of { stringifyObjects, timeZone, forbidQualified } which have the same meaning as when used with sqlstring.

const timeZone = 'GMT'
const date = new Date(Date.UTC(2000, 0, 1))

console.log(mysql({ timeZone })`SELECT ${date}`)
// SELECT '2000-01-01 00:00:00.000'

mysql`...`

When used as a template tag, chooses an appropriate escaping convention for each ${...} based on the context in which it appears.

mysql handles ${...} inside quoted strings as if the template matched the following grammar:

pg`...`

When used as a template tag, chooses an appropriate escaping convention for each ${...} based on the context in which it appears.

pg handles ${...} inside quoted strings as if the template matched the following grammar:

SqlFragment

SqlFragment is a Mintable class that represents fragments of SQL that are safe to send to a database.

See minting for example on how to create instances, and why this is a tad more involved than just using new.

SqlId

SqlId is a Mintable class that represents a SQL identifier.

See minting for example on how to create instances, and why this is a tad more involved than just using new.

A SqlId's content must be the raw text of a SQL identifier and creators should not rely on case folding by the database client.