mirror of https://github.com/moparisthebest/mail
119 lines
2.6 KiB
JavaScript
119 lines
2.6 KiB
JavaScript
/**
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* Handles generic caching of JSON objects in a lawnchair adapter
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*/
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app.dao.LawnchairDAO = function(Lawnchair) {
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'use strict';
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var db = new Lawnchair({
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name: 'data-store'
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}, function(lc) {
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if (!lc) {
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throw new Error('Lawnchair init failed!');
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}
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});
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/**
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* Create or update an object
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*/
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this.persist = function(key, object, callback) {
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db.save({
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key: key,
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object: object
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}, callback);
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};
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/**
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* Persist a bunch of items at once
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*/
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this.batch = function(list, callback) {
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db.batch(list, callback);
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};
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/**
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* Read a single item by its key
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*/
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this.read = function(key, callback) {
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db.get(key, function(o) {
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if (o) {
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callback(o.object);
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} else {
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callback(null);
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}
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});
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};
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/**
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* List all the items of a certain type
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* @param type [String] The type of item e.g. 'email'
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* @param offset [Number] The offset of items to fetch (0 is the last stored item)
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* @param num [Number] The number of items to fetch (null means fetch all)
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*/
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this.list = function(type, offset, num, callback) {
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var i, list = [],
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matchingKeys = [],
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parts, timeStr, time;
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// get all keys
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db.keys(function(keys) {
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// check if key begins with type
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for (i = 0; i < keys.length; i++) {
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if (keys[i].indexOf(type) === 0) {
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matchingKeys.push(keys[i]);
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}
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}
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// sort keys by type and date
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matchingKeys = _.sortBy(matchingKeys, function(key) {
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parts = key.split('_');
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timeStr = parts[parts.length - 2];
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time = parseInt(timeStr, 10);
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return time;
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});
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// if num is null, list all items
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num = (num !== null) ? num : matchingKeys.length;
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// set window of items to fetch
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if (offset + num < matchingKeys.length) {
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matchingKeys = matchingKeys.splice(matchingKeys.length - offset - num, num);
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} else if (offset + num >= matchingKeys.length && offset < matchingKeys.length) {
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matchingKeys = matchingKeys.splice(0, matchingKeys.length - offset);
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} else {
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matchingKeys = [];
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}
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// return if there are no matching keys
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if (matchingKeys.length === 0) {
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callback(list);
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return;
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}
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// fetch all items from data-store with matching key
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db.get(matchingKeys, function(matchingList) {
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for (i = 0; i < matchingList.length; i++) {
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list.push(matchingList[i].object);
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}
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// return only the interval between offset and num
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callback(list);
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});
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});
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};
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/**
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* Removes an object liter from local storage by its key (delete)
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*/
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this.remove = function(key, callback) {
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db.remove(key, callback);
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};
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/**
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* Clears the whole local storage cache
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*/
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this.clear = function(callback) {
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db.nuke(callback);
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};
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}; |