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Backbone sessionStorage Adapter
/**
* Backbone sessionStorage Adapter
* Based on https://github.com/jeromegn/Backbone.localStorage
*/
(function() {
// A simple module to replace `Backbone.sync` with *sessionStorage*-based
// persistence. Models are given GUIDS, and saved into a JSON object. Simple
// as that.
// Hold reference to Underscore.js and Backbone.js in the closure in order
// to make things work even if they are removed from the global namespace
var _ = this._;
var Backbone = this.Backbone;
// Generate four random hex digits.
function S4() {
return (((1+Math.random())*0x10000)|0).toString(16).substring(1);
};
// Generate a pseudo-GUID by concatenating random hexadecimal.
function guid() {
return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());
};
// Our Store is represented by a single JS object in *sessionStorage*. Create it
// with a meaningful name, like the name you'd give a table.
// window.Store is deprectated, use Backbone.SessionStorage instead
Backbone.SessionStorage = window.Store = function(name) {
this.name = name;
var store = this.sessionStorage().getItem(this.name);
this.records = (store && store.split(",")) || [];
};
_.extend(Backbone.SessionStorage.prototype, {
// Save the current state of the **Store** to *sessionStorage*.
save: function() {
this.sessionStorage().setItem(this.name, this.records.join(","));
},
// Add a model, giving it a (hopefully)-unique GUID, if it doesn't already
// have an id of it's own.
create: function(model) {
if (!model.id) {
model.id = guid();
model.set(model.idAttribute, model.id);
}
this.sessionStorage().setItem(this.name+"-"+model.id, JSON.stringify(model));
this.records.push(model.id.toString());
this.save();
return model.toJSON();
},
// Update a model by replacing its copy in `this.data`.
update: function(model) {
this.sessionStorage().setItem(this.name+"-"+model.id, JSON.stringify(model));
if (!_.include(this.records, model.id.toString())) this.records.push(model.id.toString()); this.save();
return model.toJSON();
},
// Retrieve a model from `this.data` by id.
find: function(model) {
var stored = this.sessionStorage().getItem(this.name+"-"+model.id);
if(stored) {
return JSON.parse(stored);
} else {
return null;
}
},
// Return the array of all models currently in storage.
findAll: function() {
return _(this.records).chain()
.map(function(id){return JSON.parse(this.sessionStorage().getItem(this.name+"-"+id));}, this)
.compact()
.value();
},
// Delete a model from `this.data`, returning it.
destroy: function(model) {
this.sessionStorage().removeItem(this.name+"-"+model.id);
this.records = _.reject(this.records, function(record_id){return record_id == model.id.toString();});
this.save();
return model;
},
sessionStorage: function() {
return sessionStorage;
}
});
// sessionSync delegate to the model or collection's
// *sessionStorage* property, which should be an instance of `Store`.
// window.Store.sync and Backbone.sessionSync is deprectated, use Backbone.SessionStorage.sync instead
Backbone.SessionStorage.sync = function(method, model, options, error) {
var store = model.sessionStorage || model.collection.sessionStorage;
// Backwards compatibility with Backbone <= 0.3.3
if (typeof options == 'function') {
options = {
success: options,
error: error
};
}
var resp, syncDfd = $.Deferred();
switch (method) {
case "read": resp = model.id != undefined ? store.find(model) : store.findAll(); break;
case "create": resp = store.create(model); break;
case "update": resp = store.update(model); break;
case "delete": resp = store.destroy(model); break;
}
if (resp) {
options.success(resp);
syncDfd.resolve();
} else {
if(options.error) {
options.error("Record not found");
}
syncDfd.reject();
}
return syncDfd.promise();
};
Backbone.SessionStorage.ajaxSync = Backbone.sync;
Backbone.sessionStorageEnabled = true;
Backbone.bypassSessionStorage = function(obj, func, options) {
Backbone.sessionStorageEnabled = false;
var result = func.call(obj, options || {});
Backbone.sessionStorageEnabled = true;
return result;
}
Backbone.getSyncMethod = function(model) {
if((model.sessionStorage || (model.collection && model.collection.sessionStorage)) && Backbone.sessionStorageEnabled)
{
return Backbone.SessionStorage.sync;
}
return Backbone.SessionStorage.ajaxSync;
};
// Override 'Backbone.sync' to default to localSync,
// the original 'Backbone.sync' is still available in 'Backbone.ajaxSync'
Backbone.sync = function(method, model, options, error) {
return Backbone.getSyncMethod(model).apply(this, [method, model, options, error]);
};
})();
Owner

davemo commented Mar 20, 2013

Updated to work with Backbone 1.0 (and dropped backwards compatibility with ancient versions).

craigjh commented Mar 17, 2015

Have you considered adding some text to describe whether your code is in the public domain or under the provisions of a certain license?

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