2.Model Underscore Methods(Official Tutorials)

Underscore.js  to provide 6 object functions on Backbone.Model . They aren't all documented here, but you can take a look at the Underscore documentation for the full details…

validate model.validate(attributes, options)  

This method is left undefined, and you're encouraged to override it with your custom validation logic.

By default validate is called before save, but can also be called before set if {validate:true}is passed. 

The  validate  method is passed the model attributes, as well as the options from  set  or  save . If the attributes are valid, don't return anything from  validate ; if they are invalid, return an error of your choosing.

Failed validations trigger an  "invalid" event, and set the  validationError  property on the model with the value returned by this method.

var Chapter = Backbone.Model.extend({ validate: function(attrs, options) { if (attrs.end < attrs.start) { return "can't end before it starts"; } } }); var one = new Chapter({ title : "Chapter One: The Beginning" }); one.on("invalid", function(model, error) { alert(model.get("title") + " " + error); }); one.save({ start: 15, end: 10 });

如果我们想要对Model.set()进行验证，则只需要加上{validate:true}即可，例如：

one.set( { start : 15,end : 10,} , {validate : true} );

validationError model.validationError  

The value returned by  validate  during the last failed validation.

one.on('invalid',function(model,error){

    alert(model.validationError);

    alert(model.get('title')+ ' ' + error);

  })

isValid model.isValid  

Run  validate  to check the model state.(相当于这个验证有没有返回错误，这样我们就不必要绑定invalid函数了,但是需要记住的是，这里的set就不要加   {validate : true}  了，因为我们是在set后再进行判断的  )

ar Chapter = Backbone.Model.extend({ validate: function(attrs, options) { if (attrs.end < attrs.start) { return "can't end before it starts"; } } }); var one = new Chapter({ title : "Chapter One: The Beginning" }); one.set({ start: 15, end: 10 }); if (!one.isValid()) { alert(one.get("title") + " " + one.validationError); }
 

url model.url()  

Generates URLs of the form:  "[collection.url]/[id]"  by default, but you may override by specifying an explicit  urlRoot  if the model's collection shouldn't be taken into account. You can also pass in the model's  url  as an option when instantiating it.

Delegates to  Collection#url  to generate the URL, so make sure that you have it defined, or a  urlRoot property。

urlRoot model.urlRoot or model.urlRoot()  

Specify a  urlRoot  if you're using a model  outside  of a collection, to enable the default  url function to generate URLs based on the model id. "[urlRoot]/id"

var Book = Backbone.Model.extend({urlRoot : '/books'}); var solaris = new Book({id: "1083-lem-solaris"}); alert(solaris.url());  

parse model.parse(response, options)  

parse  is called whenever a model's data is returned by the server, in  fetch , and  save .  The function is passed the raw  response  object, and should return the attributes hash to be  set  on the model.  The default implementation is a no-op, simply passing through the JSON response. Override this if you need to work with a preexisting API, or better namespace your responses.

clone model.clone()  

Returns a new instance of the model with identical attributes.

var two;

two = one.clone();

console.log(two.toJSON());

isNew model.isNew()  

Has this model been saved to the server yet? If the model does not yet have an  id , it is considered to be new.

hasChanged model.hasChanged([attribute])  

Has the model changed since the last  "change"  event? If an  attribute  is passed, returns  true  if that specific attribute has changed.

Note that this method, and the following change-related ones, are only useful during the course of a "change"  event.

book.on("change", function() { if (book.hasChanged("title")) { ... } });

changedAttributes model.changedAttributes([attributes])  

Retrieve a hash of only the model's attributes that have changed, or false  if there are none. Optionally, an external  attributes  hash can be passed in, returning the attributes in that hash which differ from the model. This can be used to figure out which portions of a view should be updated, or what calls need to be made to sync the changes to the server.

previous model.previous(attribute)  

During a  "change"  event, this method can be used to get the previous value of a changed attribute.

var bill = new Backbone.Model({ name: "Bill Smith" }); bill.on("change:name", function(model, name) { alert("Changed name from " + bill.previous("name") + " to " + name); }); bill.set({name : "Bill Jones"});

previousAttributes model.previousAttributes()  

Return a copy of the model's previous attributes. Useful for getting a diff between versions of a model, or getting back to a valid state after an error occurs.