Flutter shareable package of object-oriented classes for local caching of user data in json

json_cache

json cache is an object-oriented package to serve as a layer on top of local storage packages – packages that persist data locally on the user’s device -, unifying them as an elegant cache api.

in addition, this package gives the programmer great flexibility; it provides a set of classes that can be selected and combined in various ways to address specific caching requirements.

why json?

• because most of the local storage packages available for flutter applications
  use json as the data format.
• there is an one-to-one relationship between the dart’s built-in type
  map<string, dynamic> and json, which makes json encoding/decoding a
  trivial task.

getting started

jsoncache – the core interface of this package – represents the concept of
cached data. it is defined as:

/// represents a cached json data.
abstract class jsoncache {
  /// frees up cache storage space.
  future<void> clear();

  /// refreshes some cached data by its associated key.
  future<void> refresh(string key, map<string, dynamic> data);

  /// erases [key] and returns its associated data.
  future<map<string, dynamic>?> erase(string key);

  /// recovers some cached data; null if a cache miss occurs - no [key] found.
  future<map<string, dynamic>?> recover(string key);
}

it’s reasonable to consider each cache entry (pair of key/data) as a group of
related data. thus, it is expected to cache user data in groups, in which a key
represents the name of a single group of data. example:

'profile': {'name': 'john doe', 'email': '[email protected]', 'accounttype': 'premium'};
'preferences': {'theme': {'dark': true}, 'notifications':{'enabled': true}}

above the ‘profile’ key is associated with the group of profile related data;
‘preferences’, with preferences data.