JModel - Simple NodeJS Models

Inspired by nodejs-model (https://github.com/asaf/nodejs-model), JModel is a library designed to help with the definition, validation and filtering of models in your NodeJS application.

Why use JModel

JModel helps you define and enforce the attributes of your models. It also provides some low-level utilities for common functionality such as model validation and property filtering. This library is highly extensible and default behaviour can be added to or overwritten if it doesn't meet your needs.

Installation

To install j-model, use npm:

$ npm install j-model --save

Usage Overview

This is how it works:

var Address = jModel.create("Address", {
        attributes: [
          { name: "firstLine", type: String },
          { name: "secondLine", type: String },
          { name: "city", type: String },
          { name: "postcode", type: String }
        ]
      });
var User = jModel.create("User", {
      attributes: [
        {
          name: "name",
          type: String,
          tags: [ "public", "authenticated" ],
          validators: [
            function(value, result){
              if(value.indexOf(" ") === -1){
                result.addMessage("Name must include both forename and surname");
                return false;
              } else return true;
            }
          ]
        },
        {
          name: "email",
          type: String,
          tags: [ "authenticated" ],
          validators:[
            jModel.validators.email("Please supply a valid email address")
          ]
        },
        { name: "dateOfBirth", type: Date, tags: [ "authenticated" ] },
        { name: "admin", type: Boolean, tags: [ "public" ] },
        { name: "roles", type: [ String ], tags: [ "public" ] },
        { name: "addresses", type: [ Address ] }
        { name: "getRolesString", type: Function, fn: function(){
          return this.roles.join(", ");
        }
      ],
      init: function(constructorData){
        if(!constructorData.name) this.name = "John Doe";
        if(!constructorData.dateOfBirth) this.dateOfBirth = new Date(0);
      },
      validators: [
        { name: "Admin user email required", fn: function(model, result){
          setTimeout(function() {
            if (model.admin && !model.email) {
              result.addMessage("Admin users must have an email address");
              result.done(false);
            }
            result.done(true);
          });
        }}
      ]
    });
var u1 = new User({ admin: true });

var limitedU1 = jModel.filter.reduce(u1, [ "public" ])

// limitedU1.name === "John Doe"
// limitedU1.dateOfBirth === undefined

limitedU1 = jModel.filter.reduce(u1, [ "authenticated" ])

// limitedU1.name === "John Doe"
// limitedU1.dateOfBirth === new Date(0)

jModel.validate(u1, function(result){
  // result.valid === false
  // result.global.valid === false
  // result.global.messages[0].name === "Admin user email required"
  // result.global.messages[0].message = "Admin users must have an email address";
});

u1.email = "bad email @ddress";

jModel.validate(u1, function(result){
  // result.valid === false
  // result.attribute.valid === false
  // result.attribute.messages[0].name === "email"
  // result.attribute.messages[0].message = "Please supply a valid email address";
});

// Validate "public" (tagged) attribute values only
jModel.validate(u1, [ "public" ], function(result){
  // result.valid === true
  // result.attribute.valid === true
});

u1.name = "John";

jModel.validate(u1, function(result){
  // result.valid === false
  // result.attribute.valid === false
  // result.attribute.messages[0].name === "name"
  // result.attribute.messages[0].message = "Name must include both forename and surname";
});

// Serialises to a normal object
// JSON.stringify(u1) === "{"name":"John","admin":true}"

Model Tag Filtering

Use the jModel.filter.reduce() function to project a limited version of the model.

var User = jModel.create("User", {
    attributes: [
      { name: "name", type: String, tags: [ "public", "admin" ]},
      { name: "email", type: String, tags: [ "private", "admin" ]}
    ]
  }),
  u1 = new User({ name: "John Doe", email: "[email protected]" }),
  filteredU1 = jModel.filter.reduce(u1, [ "public" ]);

assert.equal(filteredU1.name, "John Doe");
assert.equal(typeof filteredU1.email, "undefined");

Nested Model Tag Filtering

var Address = jModel.create("Address", {
    attributes: [
      { name: "firstLine", type: String, tags: [ "short" ] },
      { name: "secondLine", type: String },
      { name: "city", type: String },
      { name: "postcode", type: String, tags: [ "short" ] }
    ]
  }),
  User = jModel.create("User", {
    attributes: [
      { name: "roles", type: [ String ] },
      { name: "address", type: Address, nestedModelTags: [ "short" ] }
    ]
  }),
  u1 = new User({ address: new Address({
      firstLine: "123 Somelane",
      secondLine: "Whereville"
    })
  });

assert.equal(u1.address.firstLine, "123 Somelane");
assert.equal(typeof u1.address.secondLine, "undefined");

Custom types

Teach it about new types:

var User, u1;
jModel.converterFactory.registerConverter("customExample", function(value, attribute){
  // Transform the value if necessary
  return value.b;
});

User = jModel.create("User", {
    attributes: [
      { name: "name", type: String },
      { name: "foo", type:"customExample" }
    ]
  });

u1 = new User({ name: "John Doe", foo: { b: "bar" } });
assert.equal(u1.foo, "bar");
u1.foo = { b: "foo" };
assert.equal(u1.foo, "foo");

To-do

• Enums
• Aliases