84 lines
2.4 KiB
JavaScript
84 lines
2.4 KiB
JavaScript
// A simple module to replace `Backbone.sync` with *localStorage*-based
|
|
// persistence. Models are given GUIDS, and saved into a JSON object. Simple
|
|
// as that.
|
|
|
|
// 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 *localStorage*. Create it
|
|
// with a meaningful name, like the name you'd give a table.
|
|
var Store = function(name) {
|
|
this.name = name;
|
|
var store = localStorage.getItem(this.name);
|
|
this.data = (store && JSON.parse(store)) || {};
|
|
};
|
|
|
|
_.extend(Store.prototype, {
|
|
|
|
// Save the current state of the **Store** to *localStorage*.
|
|
save: function() {
|
|
localStorage.setItem(this.name, JSON.stringify(this.data));
|
|
},
|
|
|
|
// 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 = model.attributes.id = guid();
|
|
this.data[model.id] = model;
|
|
this.save();
|
|
return model;
|
|
},
|
|
|
|
// Update a model by replacing its copy in `this.data`.
|
|
update: function(model) {
|
|
this.data[model.id] = model;
|
|
this.save();
|
|
return model;
|
|
},
|
|
|
|
// Retrieve a model from `this.data` by id.
|
|
find: function(model) {
|
|
return this.data[model.id];
|
|
},
|
|
|
|
// Return the array of all models currently in storage.
|
|
findAll: function() {
|
|
return _.values(this.data);
|
|
},
|
|
|
|
// Delete a model from `this.data`, returning it.
|
|
destroy: function(model) {
|
|
delete this.data[model.id];
|
|
this.save();
|
|
return model;
|
|
}
|
|
|
|
});
|
|
|
|
// Override `Backbone.sync` to use delegate to the model or collection's
|
|
// *localStorage* property, which should be an instance of `Store`.
|
|
Backbone.sync = function(method, model, success, error) {
|
|
|
|
var resp;
|
|
var store = model.localStorage || model.collection.localStorage;
|
|
|
|
switch (method) {
|
|
case "read": resp = model.id ? 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) {
|
|
success(resp);
|
|
} else {
|
|
error("Record not found");
|
|
}
|
|
}; |