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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]);
};
})();
@davemo
Owner

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

@craigjh

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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