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prep-composer

prep-composer is a lightweight JavaScript utility that facilitates convenient and safe composition of SQL statements by automatically managing and escaping parameters.

Features

  • Inline Parameter Values: Simplifies SQL writing by automatically managing the order and number of parameter values. No placeholders and separate parameter list.
  • Modular SQL Composition: Allows the creation of complex SQL statements through independent, reusable segments.
  • Identifier Escaping: Supports escaping of identifiers for enhanced security.
  • Flexible Integration: Compatible with established escaping utilities like sqlstring, and supports ? placeholders for prepared statements.
  • Dialect Compatibility: Designed to work with all SQL dialects; identifier escaping is currently optimized for MySQL and compatible databases using `backtick` escaping.

Usage

const {sql, $} = require('prep-composer');
const SqlString = require('sqlstring'); // optional

const name = "O'Brien";
const newJobTitle = 'Senior Developer';

const updateTable = sql('UPDATE', $['my_db']['employees']); // identifier escaping is optional
const fieldsToUpdate = {
    job_title: 'Designer',
    salary: 200000,
};
const condition = sql('name =', $(name));

const query = sql(updateTable, 'SET', $(fieldsToUpdate), 'WHERE', condition);

console.log(query.toString());
// UPDATE `my_db`.`employees` SET `job_title` = ?, `salary` = ? WHERE name = ?

console.log(query.parameters);
// [ "Designer", 200000, "O'Brien" ]

console.log(query.toString(SqlString.escape));
// UPDATE `my_db`.`employees` SET `job_title` = 'Designer', `salary` = 200000 WHERE name = 'O\'Brien'

Installation

You can install prep-composer using npm:

npm install prep-composer

API documentation

sql(...args: (Fragment | Fragment[])[]): SqlSegment

Creates a new SqlSegment composed of the provided fragments. Fragments can be strings, literals, identifiers, or values. Raw SQL is typically represented by a string fragment. It will be turned into a Literal internally. An array of fragments is flattened into the SQL segment, separated by commas.

Fragment

Type definition for an SQL fragment. A fragment can be a Literal, a string (will be turned into a Literal), a Value, an Identifier or an SqlSegment.

$(value: any): Value|SqlSegment[]

Helper function to create a new Value fragment for the given value. Values represent the variable fragments of a statement that are later escaped or replaced with placeholders.

If the passed value is an array, it is turned into an array of SqlSegments by converting all the elements to values if they are not of type Literal or SqlSegment. This is practical for creating IN conditions.

If an object is passed it will be turned into a series of escaped-key=escaped-value assignments. If values are already literals, values or identifiers, they are used as is. So to set a field to a static raw SQL value, you have to wrap the value in an sql function call (e.g. { hire_date: sql('NOW()') }) otherwise it is interpreted as a parameter that has to be escaped.

$.<identifier> or $[<identifier>]

Helper to create a new Identifier fragment for the given identifier. The identifier is immediately escaped with backticks when passed to the sql function. Identifiers can be chained: $['db']['field'] (yields `db`.`field`). It is recommended to use the square brackets syntax $[<identifier>] for consistency. Dots within identifiers are preserved ($['db.field'] yields `db.field`).

SqlSegment

Represents a composite SQL segment composed of multiple fragments. A segment can be used as a part of another segment, allowing the creation of complex SQL statements.

Members:

  • toString(escapeFn?: (value: any) => string): string: Returns the SQL statement as a string. If escapeFn is provided, it will be used to escape values. Otherwise ? placeholders are output.
  • parameters: any[]: An array of parameter values extracted from the SQL segment.
  • append(fragment: Fragment | Fragment[]): SqlSegment: Returns a new SqlSegment by appending the provided fragment(s) to the current segment. As in the sql function, an array of fragments is flattened into the SQL and separated by commas. Spaces are automatically added between fragments if required.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Feel free to contribute to this project by submitting issues or pull requests. Your feedback and contributions are welcome!