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A validation plugin for Backbone.js
tag: v0.2.0

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README.md

Backbone.Validation

A validation plugin for Backbone.js inspired by Backbone.ModelBinding, and another implementation with a slightly different approach than mine at Backbone.Validations.

Getting started

It's easy to get up and running. You only need to have Backbone (including underscore.js) in your page before including the Backbone.Validation plugin. If you are using the default implementation of the callbacks, you also need to include jQuery.

Configure validation rules on the Model

To configure your validation rules, simply add a validation property with a property for each attribute you want to validate on your model. The validation rules can either be an object with one of the built-in validators or a combination of two or more of them, or a function where you implement your own custom validation logic. If you want to provide a custom error message when using one of the built-in validators, simply define the msg property with your message.

Example

var SomeModel = Backbone.Model.extend({
  validation: {
    name: {
      required: true,
      msg: 'Name is required'
    },
    age: {
      range: [1, 80]
    },
    email: {
      pattern: 'email'  
    },
    someAttribute: function(value) {
      if(value !== 'somevalue') {
        return 'Error'; 
      }
    }
  }
});

See the built-in validators section in this readme for a list of the validators and patterns that you can use.

Validation binding

The validation binding code is executed with a call to Backbone.Validation.bind(view). The validate method on the view's model is then overridden to perform the validation.

There are several places that it can be called from, depending on your circumstances.

// Binding when rendering
var SomeView = Backbone.View.extend({
  render: function(){
    Backbone.Validation.bind(this);
  }
});

// Binding when initializing
var SomeView = Backbone.View.extend({
  initialize: function(){
    Backbone.Validation.bind(this);
  }
});

// Binding from outside a view
var SomeView = Backbone.View.extend({
});
var someView = new SomeView();
Backbone.Validation.bind(someView);

A couple of conventions

After performing validation, an isValid attribute is set on the model that is (obviously) true when all the attributes on the model is valid, otherwise false.

The Backbone.Validation.callbacks contains two methods: valid and invalid. These are called (in addition to the error event raised by Backbone) after validation of an attribute is performed.

The default implementation of invalid tries to look up an element within the view with an id equal to the name of the attribute that is validated. If it finds one, an invalid class is added to the element as well as a data-error attribute with the error message. The valid method removes these if they exists.

The default implementation of these can of course be overridden:

_.extend(Backbone.Validation.callbacks, {
  valid: function(view, attr, selector) {
    // do something
  },
  invalid: function(view, attr, error, selector) {
    // do something
  }
});

You can also override these per view when binding:

var SomeView = Backbone.View.extend({
  render: function(){
    Backbone.Validation.bind(this, {
      valid: function(view, attr) {
        // do something
      },
      invalid: function(view, attr, error) {
        // do something
      }
    });
  }
});

If you need to look up elements by using class name instead if id, there is two ways to configure this.

You can configure it globally by calling:

Backbone.Validation.setDefaultSelector('class');

Or, you can configure it per view when binding:

Backbone.Validation.bind(this.view, {
    selector: 'class'
});

If you have set the global selector to class, you can of course set the selector to id on specific views.

The built-in validators

method validator

var SomeModel = Backbone.Model.extend({
  validation: {
    name: function(value) {
      if(value !== 'something') {
        return 'Name is invalid';
      }
    }
  }
});

named method validator

var SomeModel = Backbone.Model.extend({
  validation: {
    name: 'validateName'
  },
  validateName: function(value) {
    if(value !== 'something') {
      return 'Name is invalid';
    }
  }
});

required

var SomeModel = Backbone.Model.extend({
  validation: {
    name: {
      required: true | false
    }
  }
});

var SomeModel = Backbone.Model.extend({
  validation: {
    name: {
      required: function() {
        return true | false;
      }
    }
  }
});

acceptance

var SomeModel = Backbone.Model.extend({
  validation: {
    termsOfUse: {
      acceptance: true
    }
  }
});

min

var SomeModel = Backbone.Model.extend({
  validation: {
    age: {
      min: 1
    }
  }
});

max

var SomeModel = Backbone.Model.extend({
  validation: {
    age: {
      max: 100
    }
  }
});

range

var SomeModel = Backbone.Model.extend({
  validation: {
    age: {
      range: [1, 10]
    }
  }
});

length

var SomeModel = Backbone.Model.extend({
  validation: {
    postalCode: {
      length: 4
    }
  }
});

minLength

var SomeModel = Backbone.Model.extend({
  validation: {
    password: {
      minLength: 8
    }
  }
});

maxLength

var SomeModel = Backbone.Model.extend({
  validation: {
    password: {
      maxLength: 100
    }
  }
});

rangeLength

var SomeModel = Backbone.Model.extend({
  validation: {
    password: {
      rangeLength: [6, 100]
    }
  }
});

oneOf

var SomeModel = Backbone.Model.extend({
  validation: {
    country: {
      oneOf: ['Norway', 'Sweeden']
    }
  }
});

equalTo

var SomeModel = Backbone.Model.extend({
  validation: {
    password: {
      required: true
    },
    passwordRepeat: {
        equalTo: 'password'
    }
  }
});

pattern

var SomeModel = Backbone.Model.extend({
  validation: {
    email: {
      pattern: 'email'
    }
  }
});

where the built-in patterns are:

  • number
  • email
  • url
  • digits

or specify any regular expression you like:

var SomeModel = Backbone.Model.extend({
  validation: {
    email: {
      pattern: /^sample/
    }
  }
});

See the wiki for more details about the validators.

Extending Backbone.Validation

Adding custom validators

If you have custom validation logic that are used several places in your code, you can extend the validators with your own. And if you don't like the default implementation of one of the built-ins, you can override it.

_.extend(Backbone.Validation.validators, {
  myValidator: function(value, attr, customValue, model) {
    if(value !== customValue){
      return 'error';
    }
  },
  required: function(value, attr, customValue, model) {
    if(!value){
      return 'My version of the required validator';
    }
  }, 
});

var Model = Backbone.Model.extend({
  validation: {
    age: {
      myValidator: 1 // uses your custom validator
    }
  }
});

The validator should return an error message when the value is invalid, and nothing (undefined) if the value is valid. If the validator returns false, this will result in that all other validators specified for the attribute is bypassed, and the attribute is considered valid.

Adding custom patterns

If you have custom patterns that are used several places in your code, you can extend the patterns with your own. And if you don't like the default implementation of one of the built-ins, you can override it.

_.extend(Backbone.Validation.patterns, {
  myPattern: /my-pattern/,
  email: /my-much-better-email-regex/
});

var Model = Backbone.Model.extend({
  validation: {
    name: {
      pattern: 'myPattern'
    }
  }
});

Overriding the default error messages

If you don't like the default error messages there are two ways of customizing them. You can either specify the msg attribute when configuring your validation, or you can override the default ones globally.

_.extend(Backbone.Validation.messages, {
    required: 'This field is required'
});

The message can contain placeholders for arguments that will be replaced:

  • {0} will be replaced with the name of the attribute being validated
  • {1} will be replaced with the allowed value configured in the validation (or the first one in a range validator)
  • {2} will be replaced with the second value in a range validator

Release notes

v0.2.0

  • New validators:
    • named method
    • length
    • acceptance (which is typically used when the user has to accept something (e.g. terms of use))
    • equalTo
    • range
    • rangeLength
    • oneOf
  • Added possibility to validate entire model by explicitly calling model.validate() without any parameters. (Note: Backbone.Validation.bind(..) must still be called)
  • required validator can be specified as a method returning either true or false
  • Can override the default error messages globally
  • Can override the id selector (#) used in the callbacks either globally or per view when binding
  • Improved email pattern for better matching
  • Added new pattern 'digits'
  • Possible breaking changes:
    • Removed the unused msg parameter when adding custom validators
    • Number pattern matches negative numbers (Fixes issue #4), decimals and numbers with 1000-separator (e.g. 123.000,45)
    • Context (this) in the method validators is now the model instead of the global object (Fixes issue # 6)
    • All validators except required and acceptance invalidates null, undefined or empty value. However, required:false can be specified to allow null, undefined or empty value
  • Breaking changes (unfortunate, but necessary):
    • Required validator no longer invalidates false boolean, use the new acceptance validator instead

v0.1.3

  • Fixed issue where min and max validators treated strings with leading digits as numbers
  • Fixed issue with undefined Backbone reference when running Backbone in no conflict mode
  • Fixed issue with numeric string with more than one number not being recognized as a number

v0.1.2

  • Initial release

License

http://thedersen.mit-license.org/

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