model-key-composer.js
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// Copyright IBM Corp. 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
'use strict';
var createPromiseCallback = require('./utils').createPromiseCallback;
var debug = require('debug')('loopback:connector:model-key-composer');
var g = require('strong-globalize')();
/**
* Build a single key string from a tuple (modelName, key).
*
* This method is typically used by KeyValue connectors to build a single
* key string for a given modelName+key tuple.
*
* @param {String} modelName
* @param {String} key
* @callback {Function} cb The callback to receive the composed value.
* @param {Error} err
* @param {String} composedKey
* @promise
*/
exports.compose = function composeKeyFromModelNameAndKey(modelName, key, cb) {
cb = cb || createPromiseCallback();
// Escape model name to prevent collision
// 'model' + 'foo:bar' --vs-- 'model:foo' + 'bar'
var value = encodeURIComponent(modelName) + ':' + key;
setImmediate(function() {
cb(null, value);
});
return cb.promise;
};
var PARSE_KEY_REGEX = /^([^:]*):(.*)/;
/**
* Parse a composed key string into a tuple (modelName, key).
*
* This method is typically used by KeyValue connectors to parse a composed
* key string returned by SCAN/ITERATE method back to the expected
* modelName+tuple key.
*
* @param {String} composed The composed key as returned by `composeKey`
* @callback {Function} cb The callback to receive the parsed result.
* @param {Error} err
* @param {Object} result The result with properties `modelName` and `key`.
* @promise
*/
exports.parse = function(composed, cb) {
cb = cb || createPromiseCallback();
var matchResult = composed.match(PARSE_KEY_REGEX);
if (matchResult) {
var result = {
modelName: matchResult[1],
key: matchResult[2],
};
setImmediate(function() {
cb(null, result);
});
} else {
debug('Invalid key - missing model-name prefix: %s', composed);
var err = new Error(g.f(
'Invalid key %j - missing model-name prefix',
composed));
err.code = 'NO_MODEL_PREFIX';
setImmediate(function() {
cb(err);
});
}
return cb.promise;
};