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| var _ = require('lodash'),
async = require('async'),
nano = require('nano'),
url = require('url');
/**
* class Db
*
* @param {String} _url: CouchDB URL in format http(s)://user:pass@host:port/db for database,
* and http(s)://user:pass@host:port/db/design/view for view
*/
function Db(_url, opts) {
opts = opts || {};
var dbPath = url.parse(_url.replace(/\/$/, '')).pathname.replace(/^\//, ''),
dbPathElems = dbPath.split('/'),
dbUrl;
if (dbPathElems.length === 1) {
this.dbName = dbPathElems[0];
} else {
this.dbName = dbPathElems[0];
this.dbDesign = dbPathElems[1];
this.dbView = dbPathElems[2];
}
dbUrl = _url.replace(new RegExp(dbPath + '$', 'g'), '');
this.db = opts.db || nano(dbUrl).use(this.dbName);
this.inProgress = 0;
}
/**
* Retrieve documents in CouchDB database or view, page by page.
* This implements linked list pagination - http://guide.couchdb.org/draft/recipes.html#fast .
*
* @param {Number} interval: interval between page retrievals, in milliseconds
* @param {String} startKey: key of the first document to retrieve, null indicates the first document in the database
* @param {String} endKey: key of the last document to retrieve
* @param {String} pageSize: how many documents to retrieve per page
* @param {String} numPages: how many pages to retrieve, undefined means all
* @param {Function} pageCb: a callback function to process documents per page retrieval
* @param {Function} cb: standard cb(err, result) callback
*/
Db.prototype.paginate = function (interval, startKey, endKey, pageSize, numPages, pageCb, cb) {
var done = false,
pageCount = 0,
key = startKey,
key_docid = startKey,
self = this;
function _action(cb) {
// both startkey and startkey_docid are specified to handle a view index with duplicated keys
var opts = {
startkey: key,
startkey_docid: key_docid,
limit: pageSize + 1,
include_docs: true
};
// unlike startkey/startkey_docid, null endkey/endkey_docid does not mean last document in the database
// don't set endkey_docid option unless endKey argument is set
if (endKey) {
opts.endkey = endKey;
opts.endkey_docid = endKey;
}
function _actionCb(err, result) {
if (err) {
cb(err);
} else {
pageCb(result.rows);
// when the number of retrieved documents is less than the limit,
// or the page count is the number of pages to retrieve,
// that means it's the last page
if (result.rows.length < opts.limit || pageCount === numPages - 1) {
done = true;
interval = 0;
// if not last page, then use the last document's key/id as the startkey/startkey_docid of the first document on the next page
} else {
key = result.rows[result.rows.length - 1].key;
key_docid = result.rows[result.rows.length - 1].id;
pageCount++;
}
setTimeout(cb, interval);
}
}
if (self.dbView) {
self.db.view(self.dbDesign, self.dbView, opts, _actionCb);
} else {
self.db.list(opts, _actionCb);
}
}
function _check() {
return done === true;
}
function _end(err) {
cb(err);
}
async.until(_check, _action, _end);
};
/**
* Bulk update an array of documents.
*
* @param {Array} docs: documents to be bulk updated
* @param {Function} cb: standard cb(err, result) callback
*/
Db.prototype.update = function (docs, cb) {
this.inProgress += 1;
var self = this;
// NOTE: when CouchDB instance requires authentication and the URL does not supply a username and password,
// nano bulk callback is called with null error and unmodified documents in CouchDB as the result, ignoring the modified documents.
// Ideally nano should pass an error.
this.db.bulk({ docs: docs }, function (err, result) {
self.inProgress -= 1;
cb(err, result);
});
};
/**
* Check if there's any database operation (documents save/remove) in progress.
*
* @return {Boolean} true if there's no database operation in progress, false otherwise.
*/
Db.prototype.done = function () {
return this.inProgress === 0;
};
module.exports = Db;
|