Offline Cache for storing simple data

Use when you need to save some data into local memory. This API provides you with approach similar to the HTML5's Local Storage, but implemented internally via native device API and completely device agnostic. We do not recommend using a different storage type then Offline Cache or full featured File System API that will provide you with more low-level methods.

All methods

Method	Description	Supported Since
loadContent()	Loads content from internal storage	1.0.3
saveContent()	Saves content to internal storage	1.0.3
listContents()	List all content items saved previously to internal storage	2.0.0
deleteContent()	Delete content item previously saved to internal storage	2.0.0

warning

Emulator has certain limitations while handling offline files. Read more here

loadContent()

Method loadContent() loads content from internal storage.

Parameters

Param	Type	Required	Description
uid	string	Yes	Unique file identifier is used for later file retrieval, must contain a-z,A-Z,0-9 and . characters

Javascript example

await sos.offline.cache.saveContent('ApplicationSecret', '123SuperSecretHash');

saveContent()

Method for saving content into internal storage.

Parameters

Param	Type	Required	Description
uid	string	Yes	Unique file identifier is used for later file retrieval, must contain a-z,A-Z,0-9 and . characters
content	string	Yes	Only string variables enabled. For JSON values use JSON.Stringify()

Javascript Example

sos.offline.cache.saveContent('ApplicationSecret', '123SuperSecretHash')
.then(() => {
    //Content was successfully saved, retrieve it. 
    return sos.offline.cache.loadContent('ApplicationSecret');
})
.then((content) => {
    console.log('Loaded', content); // print 123SuperSecretHash
})

listContents()

List all content items saved previously to internal storage

Javascript example

await sos.offline.cache.listContents();

deleteContent()

Delete content item previously saved to internal storage.

Parameters

Param	Type	Required	Description
uid	string	Yes	Unique file identifier is used for later file retrieval, must contain a-z,A-Z,0-9 and . characters

Javascript example

//Store
sos.offline.cache.saveContent('ApplicationSecret', '123SuperSecretHash')
.then(() => {
    //Content was successfully saved, retrieve it. 
    return sos.offline.cache.loadContent('ApplicationSecret');
})
.then((content) => {
    console.log('Loaded', content); // print 123SuperSecretHash
 
    // Let's delete the content now
    return sos.offline.cache.deleteContent('ApplicationSecret')
})
.then(() => {
    console.log("Deleted");
})
.catch((error) => { console.error(error); });

Usage with Typescript

You can also use all these methods with signageOS TypeScript.

loadContent(uid: string): Promise<string>;
saveContent(uid: string, content: string): Promise<void>;

listContents(): Promise<string[]>;
deleteContent(uid: string): Promise<void>;

Errors

Although we are doing our best, following errors may occur when working with the offline cache.

Code	Type	Message
41001	AppletNativeCacheError	Already saving the file with UID: uid
51001	InternalNativeCacheError	Couldn't not read the files from the offline cache.
51001	InternalNativeCacheError	Couldn't load the file from offline cache.
51001	InternalNativeCacheError	Couldn't load the file before deleting it.
51002	InternalNativeCacheError	Couldn't save the file to the offline cache.
51003	InternalNativeCacheError	File wasn't deleted correctly.
40901	AppletOfflineCacheError	Uid contains invalid characters, allowed: $$ALLOWED_CHARS$$, got $$ACTUAL_UID$$