parameterized-sql.js
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// Copyright IBM Corp. 2015,2016. All Rights Reserved.
// Node module: loopback-connector
// This file is licensed under the MIT License.
// License text available at https://opensource.org/licenses/MIT
var assert = require('assert');
var PLACEHOLDER = '?';
module.exports = ParameterizedSQL;
/**
* A class for parameterized SQL clauses
* @param {String|Object} sql The SQL clause. If the value is a string, treat
* it as the template using `?` as the placeholder, for example, `(?,?)`. If
* the value is an object, treat it as {sql: '...', params: [...]}
* @param {*[]} params An array of parameter values. The length should match the
* number of placeholders in the template
* @returns {ParameterizedSQL} A new instance of ParameterizedSQL
* @constructor
*/
function ParameterizedSQL(sql, params) {
if (!(this instanceof ParameterizedSQL)) {
return new ParameterizedSQL(sql, params);
}
sql = sql || '';
if (arguments.length === 1 && typeof sql === 'object') {
this.sql = sql.sql;
this.params = sql.params || [];
} else {
this.sql = sql;
this.params = params || [];
}
assert(typeof this.sql === 'string', 'sql must be a string');
assert(Array.isArray(this.params), 'params must be an array');
var parts = this.sql.split(PLACEHOLDER);
assert(parts.length - 1 === this.params.length,
'The number of ? (' + (parts.length - 1) +
') in the sql (' + this.sql + ') must match the number of params (' +
this.params.length +
') ' + this.params);
}
/**
* Merge the parameterized sqls into the current instance
* @param {Object|Object[]} ps A parametered SQL or an array of parameterized
* SQLs
* @param {String} [separator] Separator, default to ` `
* @returns {ParameterizedSQL} The current instance
*/
ParameterizedSQL.prototype.merge = function(ps, separator) {
if (Array.isArray(ps)) {
return this.constructor.append(this,
this.constructor.join(ps, separator), separator);
} else {
return this.constructor.append(this, ps, separator);
}
};
ParameterizedSQL.prototype.toJSON = function() {
return {
sql: this.sql,
params: this.params,
};
};
/**
* Append the statement into the current statement
* @param {Object} currentStmt The current SQL statement
* @param {Object} stmt The statement to be appended
* @param {String} [separator] Separator, default to ` `
* @returns {*} The merged statement
*/
ParameterizedSQL.append = function(currentStmt, stmt, separator) {
currentStmt = (currentStmt instanceof ParameterizedSQL) ?
currentStmt : new ParameterizedSQL(currentStmt);
stmt = (stmt instanceof ParameterizedSQL) ? stmt :
new ParameterizedSQL(stmt);
separator = typeof separator === 'string' ? separator : ' ';
if (currentStmt.sql) {
currentStmt.sql += separator;
}
if (stmt.sql) {
currentStmt.sql += stmt.sql;
}
currentStmt.params = currentStmt.params.concat(stmt.params);
return currentStmt;
};
/**
* Join multiple parameterized SQLs into one
* @param {Object[]} sqls An array of parameterized SQLs
* @param {String} [separator] Separator, default to ` `
* @returns {ParameterizedSQL}
*/
ParameterizedSQL.join = function(sqls, separator) {
assert(Array.isArray(sqls), 'sqls must be an array');
var ps = new ParameterizedSQL('', []);
for (var i = 0, n = sqls.length; i < n; i++) {
this.append(ps, sqls[i], separator);
}
return ps;
};
ParameterizedSQL.PLACEHOLDER = PLACEHOLDER;