json-views: a simple DSL for defining JSON views

What is a json-view? A json-view allows you to map internal objects to external views.

Why use json-views

There are two common reasons for using json-views, consistency and security. By using views we ensure consistency to how objects are presented. Since attributes are whitelisted, this also increases security by limiting the chance of accidental internal value exposure.

Basic Example

The following example simply creates a new object that lacks the "password" field.

var user = {
  firstName: 'First',
  lastName: 'Last',
  email: 'test@example.com',
  password: 'password'
};

views.describe('user', function (desc) {
    desc.allow([ 'firstName', 'lastName', 'email' ]);
    desc.deny('password');
});

var results = views.view('user', user);

results === {
  firstName: 'First',
  lastName: 'Last',
  email: 'test@example.com'  
}

Allowing and Denying

JSON serializers works as a combination whitelist/blacklist for object attributes where attributes must first be desc.allow()'ed. desc.deny() will always take priority in cases where an attribute is both allowed and denied.

var user = {
  firstName: 'First',
  lastName: 'Last',
  email: 'test@example.com',
  password: 'password',
  address: {
    street: '1234 Example',
    city: 'Indianapolis',
    state: 'IN'
  }
};

views.describe('user.address', function(desc) {
  desc.allow('state');
});

views.describe('user', function(desc) {
  desc.allow([ 'firstName', 'lastName', 'email' ]);
  desc.deny('password');
  desc.reference('address', 'user.address');
  desc.transform(function(obj) { return obj.firstName + ' ' + obj.lastName }, { as: 'fullName' });
  desc.transform('fullName', function(obj) { return obj.firstName + ' ' + obj.lastName });
});

var results = views.view('user', user);

results === {
  firstName: 'First',
  lastName: 'Last',
  email: 'test@example.com',
  address: {
    state: 'IN'
  }
}

var results = views.view('user', user);

results === {
  firstName: 'First',
  lastName: 'Last',
  email: 'test@example.com'  
}

Nested Objects

Views can also be nested using desc.reference().

var user = {
  firstName: 'First',
  lastName: 'Last',
  email: 'test@example.com',
  password: 'password',
};

views.describe('user.address', function(desc) {
  desc.allow('state');
});

views.describe('user', function(desc) {
  desc.allow([ 'firstName', 'lastName', 'email', 'address' ]);
  desc.deny('password');
  desc.reference('address', 'user.address');
});

var results = views.view('user', user);

results === {
  firstName: 'First',
  lastName: 'Last',
  email: 'test@example.com',
  address: {
    state: 'IN'
  }
}