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request-promise-cache.js
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request-promise-cache.js
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/*
promisified version of request with cache support
*/
var request = require('request');
var cache = require('nano-cache');
var P = global.Promise;
if (! P) {
console.warn('your nodejs version does not natively support global.Promise,'
+ ' you must pass your custom class, i.e. request.use(require("bluebird")); '
+ ' see https://github.com/akhoury/request-promise-cache#other-promise-libraries'
)
}
function hashCode (str) {
// https://stackoverflow.com/a/34842797/493756
return str.split('')
.reduce(function (prevHash, currVal) { return ((prevHash << 5) - prevHash) + currVal.charCodeAt(0) }, 0);
}
function promisifyAndCachifyRequest (r, options) {
r = r || request.defaults(options || {});
r._loading = {};
r._cache = new cache();
r._cache.on('del', function (key) {
delete r._loading[key];
});
r._cache.on('clear', function () {
r._loading = {};
});
var requestPromiseCache = function(params) {
var cacheEntry = {};
var promise = cacheEntry.promise = new P(function(resolve, reject) {
var fresh = params.fresh;
var cacheKey = params.cacheKey;
var cacheTTL = params.cacheTTL;
var cacheLimit = params.cacheLimit;
if ((cacheTTL || cacheLimit) && !cacheKey) {
cacheKey = hashCode(JSON.stringify(params));
}
delete params.fresh;
delete params.cacheKey;
delete params.cacheTTL;
delete params.cacheLimit;
if ((fresh || (params.qs && params.qs._)) && cacheKey) {
r._cache.del(cacheKey);
}
var get = (params.method || 'get').toLowerCase() === 'get';
if(get && cacheKey) {
var hit = r._cache.get(cacheKey);
if (hit) {
// only works if resolveWithFullResponse=true
// since body would be a primitive string and can't add property to it.
// and I don't want to use `new String(body)`
// anyways, this is not documented and I only use it for tests
hit.__fromCache = true;
resolve(hit);
return;
}
if (r._loading[cacheKey]) {
r._loading[cacheKey].promise.done ? r._loading[cacheKey].promise.done(resolve, reject) : r._loading[cacheKey].promise.then(resolve, reject);
return;
}
r._loading[cacheKey] = cacheEntry;
}
var resolveWithFullResponse = params.resolveWithFullResponse;
delete params.resolveWithFullResponse;
r(params, function(error, response, body) {
var ret = resolveWithFullResponse ? response : body;
if (error || response.statusCode < 200 || response.statusCode > 299) {
reject(error || response);
} else {
cacheKey && get && r._cache.set(cacheKey, ret, {ttl: cacheTTL, limit: cacheLimit});
resolve(ret);
}
delete r._loading[cacheKey];
});
});
return promise;
};
requestPromiseCache.loading = r._loading;
requestPromiseCache.cache = r._cache;
return requestPromiseCache;
}
function defaults (defaults) {
var r = request.defaults(defaults || {});
return promisifyAndCachifyRequest(r);
}
var requestPromiseCache = promisifyAndCachifyRequest();
// original request()
requestPromiseCache.original = request;
// same as the original.defaults, but promisified
requestPromiseCache.defaults = defaults;
requestPromiseCache.use = function (CustomPromise) {
P = CustomPromise;
return requestPromiseCache;
};
module.exports = requestPromiseCache;