Backbone Model里面的验证方法没被调用？

Question

Beginning to learn Backbone, trying to do some simple validation inside my Person Model but the validate method doesn't seem to be run when I set a new age. Can anyone explain where i may be going wrong on this? Don't want to move on with my learning until I get this right.

JS

var Person = Backbone.Model.extend({

    defaults: {
        name: 'John Doe',
        age: 30,
        occupation: 'working'
    },

    validate: function(attrs) {

        console.log(attrs);

        if ( attrs.age < 0 ) {
            return 'Age must be positive, stupid';
        }

        if ( ! attrs.name ) {
            return 'Every person must have a name, you fool.';
        }

    },

    work: function() {
        return this.get('name') + ' is working.';
    }

});

Currently I am just getting and setting values in the console, so:

var person = new Person({
    name: 'Lady Madonna',
    age: 23
});

person.on('error', function(model, error){
    console.log(error);
});

When I set age to be a negative value the validate method doesn't take effect:

person.set('age', -55);

Answer 1

Model validation changed in Backbone 0.9.10 :

Model validation is now only enforced by default in Model#save and no longer enforced by default upon construction or in Model#set, unless the {validate:true} option is passed.

and note that

Model validation now fires invalid event instead of error .

So your code should be written as

var person = new Person({
    name: 'Lady Madonna',
    age: 23
});

person.on('invalid', function(model, error){
    console.log(error);
});

person.set('age', -55, {validate : true});

And a Fiddle http://jsfiddle.net/nikoshr/aUxdS/

Answer 2

By default, validate() gets called before a call to save() method. If you also want it to be called before set() , you should specify the { validate : true } option, for example:

person.set({ age : -55 }, { validate : true });

Answer 3

Here is an example I wrote a while back. Hope it helps:

So lets say you have a model called Animal:

var Animal = Backbone.Model.extend({
    defaults:  {
        name: '',
        speech: ''
    },
    validate: function(attribs) {
        if(attribs.name === ''){
            return "Your animal does not have a name.";
        }
    },
    initialize: function() {
        console.log('New Animal creation');
        this.on("change:name", function() {
            console.log("Change captured");
        });
        this.on("error", function(model, error) {
            console.log(error);
        });
    }
});

So when somewhere in javascript you do this:

var dog = new Animal();
dog.set('speech', 'kef');

You will receive the following message / error:

"Your Animal does not have a name."

Now the validation will not be called when creating the new object 'dog'. You really need to set it as wel using the dog.set().

Otherwise it will not produce an error.

By changing the value later on it might also not give this error. (you really need to use set I guess).

However you can always check if the model is in Valid state like this:

Model.isValid().

This will return a false when the Model is not valid. So this:

var dog = new Animal();
dog.isValid(); //would return a 'false' 

dog.set({
    'speech': 'kef',
    'name': 'fido'
});
dog.isValid(); //would return a 'true'

Hope this helps!