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jcguarinpenarandajcguarinpenaranda
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moved index to ParseOffline, and used index to export modules
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2 files changed

+147
-115
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2 files changed

+147
-115
lines changed

‎src/ParseOffline.ts‎

Lines changed: 141 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,141 @@
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import * as Parse from 'parse';
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import { CachedResults } from './CachedResults';
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export class ParseOffline {
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/**
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* Save query results in the localStorage for any class.
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* With this, given a query, you could fetch its results and
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* save them in the localStorage for later usage.
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*
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* Let's say you have a query for items of the class
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* GamePoints, they are saved as JSON in the local storage as
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* _cache_GamePoints.
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*
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* Nowadays, localStorage is widely supported
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* https://caniuse.com/#search=localStorage
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*
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* @param query
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* @param localStorageKey
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*/
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static async saveResultsToLocalStorage(params:{
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query: Parse.Query,
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localStorageKey?: string,
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options?: Parse.Query.FindOptions,
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}): Promise<Parse.Object[]> {
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const { query, localStorageKey, options } = params;
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// Generate the cache key
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const cacheKey: string = localStorageKey ||
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ParseOffline.getLocalStorageKeyForClassName(query.className);
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// Get the results
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const results = await query.find(options);
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// Save the items in the localStorage as JSON
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localStorage.setItem(
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cacheKey,
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JSON.stringify(new CachedResults(results).toJSON()),
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);
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// Return the results
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return results;
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}
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/**
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* Given a query, gets the results
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* @param query
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*/
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static getResultsFromTheLocalStorage(params: {
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className: string,
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localStorageKey?: string,
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}): CachedResults {
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const { className, localStorageKey } = params;
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const previousItems = localStorage.getItem(
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localStorageKey || // from an arbitrary key
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ParseOffline.getLocalStorageKeyForClassName(className), // for an autogenerated key
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);
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// return if there were no previous items
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if (!previousItems) return;
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// parse the previous results
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const parsedJSON: any = JSON.parse(previousItems);
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// Return the Parse Objects
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return CachedResults.fromJSON(parsedJSON);
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}
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/**
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* Returns the key to be used for saving the results
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* of a given query to the localStorage
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* @param query
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*/
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static getLocalStorageKeyForClassName(className: string): string {
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return `_cache_${className}`;
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}
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/**
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* Gets a className, given a localStorage key used to
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* save an array of items
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* @param key
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*/
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static getClassNameFromLocalStorageKey(key: string): string {
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return key.replace('_cache_', '');
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}
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/**
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* Finds the results for the given query,
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* saves them to the localStorage and gives you
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* back the results.
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*
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* In case that the browser is not onLine, tries
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* to give you back the results that were cached
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* in the localStorage
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*
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* @param query
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*/
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static async findWithFallbackAndCache(params: {
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query: Parse.Query,
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localStorageKey?: string,
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options?: Parse.Query.FindOptions,
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maxAge?: number,
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}): Promise<Parse.Object[]> {
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const { query, localStorageKey, options, maxAge } = params;
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// Get the previous items
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const previousItems = localStorage.getItem(
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localStorageKey ||
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ParseOffline.getLocalStorageKeyForClassName(query.className),
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);
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// If offline, and results were cached,
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// then parse and return them
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if (previousItems && !navigator.onLine) {
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const cachedResults = ParseOffline.getResultsFromTheLocalStorage({
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localStorageKey,
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className: query.className,
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});
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if (maxAge && !ParseOffline.areCachedResultsValid(cachedResults, maxAge)) {
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throw new Error('Cached results are not valid anymore');
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}
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return cachedResults.toParseObjs(query.className);
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}
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// Else, return the items from the network and cache them
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return ParseOffline.saveResultsToLocalStorage({
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query,
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localStorageKey,
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options,
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});
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}
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static areCachedResultsValid(
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cachedResults: CachedResults, maxAge: number,
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): boolean {
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return cachedResults.createdAt.getTime() > (new Date().getTime() - maxAge);
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}
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}

‎src/index.ts‎

Lines changed: 6 additions & 115 deletions
Original file line numberDiff line numberDiff line change
@@ -1,116 +1,7 @@
1-
import * as Parse from 'parse';
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import { ParseOffline } from './ParseOffline';
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import { CachedResults } from './CachedResults';
23

3-
import CachedResults from './CachedResults';
4-
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export class ParseOffline {
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/**
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* Save query results in the localStorage for any class.
8-
* With this, given a query, you could fetch its results and
9-
* save them in the localStorage for later usage.
10-
*
11-
* Let's say you have a query for items of the class
12-
* GamePoints, they are saved as JSON in the local storage as
13-
* _cache_GamePoints.
14-
*
15-
* Nowadays, localStorage is widely supported
16-
* https://caniuse.com/#search=localStorage
17-
*
18-
* @param query
19-
* @param localStorageKey
20-
*/
21-
static async saveResultsToLocalStorage(
22-
query: Parse.Query,
23-
localStorageKey?: string,
24-
options?: Parse.Query.FindOptions,
25-
): Promise<Parse.Object[]> {
26-
// Generate the cache key
27-
const cacheKey: string = localStorageKey ||
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ParseOffline.getLocalStorageKeyForClassName(query.className);
29-
30-
// Get the results
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const results = await query.find(options);
32-
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// Save the items in the localStorage as JSON
34-
localStorage.setItem(
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cacheKey,
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JSON.stringify(new CachedResults(results).toJSON()),
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);
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// Return the results
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return results;
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}
42-
43-
/**
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* Given a query, gets the results
45-
* @param query
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*/
47-
static async getResultsFromTheLocalStorage(
48-
className: string,
49-
localStorageKey?: string,
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) {
51-
const previousItems = localStorage.getItem(
52-
localStorageKey || // from an arbitrary key
53-
ParseOffline.getLocalStorageKeyForClassName(className), // for an autogenerated key
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);
55-
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// return if there were no previous items
57-
if (!previousItems) return;
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// parse the previous results
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const parsedJSON: any = JSON.parse(previousItems);
61-
const cachedResults: CachedResults = CachedResults.fromJSON(parsedJSON);
62-
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// Return the Parse Objects
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return cachedResults.toParseObjs(className);
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}
66-
67-
/**
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* Returns the key to be used for saving the results
69-
* of a given query to the localStorage
70-
* @param query
71-
*/
72-
static getLocalStorageKeyForClassName(className: string): string {
73-
return `_cache_${className}`;
74-
}
75-
76-
/**
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* Gets a className, given a localStorage key used to
78-
* save an array of items
79-
* @param key
80-
*/
81-
static getClassNameFromLocalStorageKey(key: string): string {
82-
return key.replace('_cache_', '');
83-
}
84-
85-
/**
86-
* Finds the results for the given query,
87-
* saves them to the localStorage and gives you
88-
* back the results.
89-
*
90-
* In case that the browser is not onLine, tries
91-
* to give you back the results that were cached
92-
* in the localStorage
93-
*
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* @param query
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*/
96-
static async findWithFallback(
97-
query: Parse.Query,
98-
localStorageKey?: string,
99-
options?: Parse.Query.FindOptions,
100-
): Promise<Parse.Object[]> {
101-
// Get the previous items
102-
const previousItems = localStorage.getItem(
103-
localStorageKey ||
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ParseOffline.getLocalStorageKeyForClassName(query.className),
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);
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// If offline, and results were cached,
108-
// then parse and return them
109-
if (previousItems && !navigator.onLine) {
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return ParseOffline.getResultsFromTheLocalStorage(query.className, localStorageKey);
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}
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// Else, return the items from the network and cache them
114-
return ParseOffline.saveResultsToLocalStorage(query);
115-
}
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}
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export {
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ParseOffline,
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CachedResults,
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};

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