node-query/lib/Driver.js

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'use strict';
const helpers = require('./helpers');
/**
* Base Database Driver
*
* @private
*/
const Driver = {
identifierStartChar: '"',
identifierEndChar: '"',
tablePrefix: null,
hasTruncate: true,
/**
* Low level function for naive quoting of strings
*
* @param {String} str - The sql fragment to quote
* @return {String} - The quoted sql fragment
* @private
*/
_quote (str) {
return (helpers.isString(str) &&
!(str.startsWith(Driver.identifierStartChar) || str.endsWith(Driver.identifierEndChar))
)
? `${Driver.identifierStartChar}${str}${Driver.identifierEndChar}`
: str;
},
/**
* Set the limit clause
* @private
* @param {String} sql - SQL statement to modify
* @param {Number} limit - Maximum number of rows to fetch
* @param {Number} [offset] - Number of rows to skip
* @return {String} - Modified SQL statement
*/
limit (sql, limit, offset) {
sql += ` LIMIT ${limit}`;
if (helpers.isNumber(offset)) {
sql += ` OFFSET ${offset}`;
}
return sql;
},
/**
* Quote database table name, and set prefix
*
* @private
* @param {String} table - Table name to quote
* @return {String} - Quoted table name
*/
quoteTable (table) {
// Quote after prefix
return Driver.quoteIdentifiers(table);
},
/**
* Use the driver's escape character to quote identifiers
*
* @private
* @param {String|Array} str - String or array of strings to quote identifiers
* @return {String|Array} - Quoted identifier(s)
*/
quoteIdentifiers (str) {
let hiers, raw;
let pattern = new RegExp(
`${Driver.identifierStartChar}(` +
'([a-zA-Z0-9_]+)' + '(((.*?)))' +
`)${Driver.identifierEndChar}`, 'ig');
// Recurse for arrays of identifiiers
if (Array.isArray(str)) {
return str.map(Driver.quoteIdentifiers);
}
// Handle commas
if (str.includes(',')) {
let parts = str.split(',').map(helpers.stringTrim);
str = parts.map(Driver.quoteIdentifiers).join(',');
}
// Split identifiers by period
hiers = str.split('.').map(Driver._quote);
raw = hiers.join('.');
// Fix functions
if (raw.includes('(') && raw.includes(')')) {
let funcs = pattern.exec(raw);
// Unquote the function
raw = raw.replace(funcs[0], funcs[1]);
// Quote the identifiers inside of the parens
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let inParens = funcs[3].substring(1, funcs[3].length - 1);
raw = raw.replace(inParens, Driver.quoteIdentifiers(inParens));
}
return raw;
},
/**
* Generate SQL to truncate the passed table
*
* @private
* @param {String} table - Table to truncate
* @return {String} - Truncation SQL
*/
truncate (table) {
let sql = (Driver.hasTruncate)
? 'TRUNCATE '
: 'DELETE FROM ';
sql += Driver.quoteTable(table);
return sql;
},
/**
* Generate SQL to insert a group of rows
*
* @private
* @param {String} table - The table to insert to
* @param {Array} [data] - The array of object containing data to insert
* @return {String} - Query and data to insert
*/
insertBatch (table, data) {
const vals = [];
const fields = Object.keys(data[0]);
let sql = '';
// Get the data values to insert, so they can
// be parameterized
data.forEach(obj => {
Object.keys(obj).forEach(key => {
vals.push(obj[key]);
});
});
// Get the field names from the keys of the first
// object inserted
table = Driver.quoteTable(table);
sql += `INSERT INTO ${table} (${Driver.quoteIdentifiers(fields).join(',')}) VALUES `;
// Create placeholder groups
let params = Array(fields.length).fill('?');
let paramString = `(${params.join(',')})`;
let paramList = Array(data.length).fill(paramString);
sql += paramList.join(',');
return {
sql: sql,
values: vals
};
}
};
module.exports = Driver;