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Introduction to Marionette.js – The Backbone Framework

Determining the Storage Key

Understand which storage key would be feasible according to the requirements of the entities.

We'll cover the following...

Creating a function to determine the storage key

We need to determine the storage key according to each entity, so let’s create a function for that:

Node.js
ContactManager.module("Entities", function(Entities, ContactManager, 
Backbone, Marionette, $, _){
  var findStorageKey = function(entity){
    // use a model's urlRoot value
    if(entity.urlRoot){
      return entity.urlRoot;
    }
    // use a collection's url value
    if(entity.url){
      return entity.url;
    }
  
    throw new Error("Unable to determine storage key"); 
  };
  var StorageMixin = function(entityPrototype){
    var storageKey = findStorageKey(entityPrototype);
    return { localStorage: new Backbone.LocalStorage(storageKey) };
  };
  
  var getEntity = function(constructorString){ 
    // code truncated for brevity
  };
  
  Entities.configureStorage = function(constructorString){ 
    // code truncated for brevity
  }; 
});

That’s a great start, but both url and urlRoot can be defined as functions. Therefore, let’s use Underscore’s result function to return the value or function result as the case may be:

Node.js
ContactManager.module("Entities", function(Entities, ContactManager, 
Backbone, Marionette, $, _){
  var findStorageKey = function(entity){
    // use a model's urlRoot value
    if(entity.urlRoot){
      return _.result(entity, "urlRoot");
    }
    // use a collection's url value
    if(entity.url){
      return _.result(entity, "url");
    }
    
    throw new Error("Unable to determine storage key"); 
  };
  
  var StorageMixin = function(entityPrototype){
    var storageKey = findStorageKey(entityPrototype);
    return { localStorage: new Backbone.LocalStorage(storageKey) };
  };
  var getEntity = function(constructorString){ 
    // code truncated for brevity
  };
  Entities.configureStorage = function(constructorString){ 
    // code truncated for brevity
  }; 
});

Great! Since we create a ...