A better syntax for mongoose instance and static methods.

mongoose.js

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/foobar');

// bootstrap mongoose, because syntax.
mongoose.createModel = function(name, options) {
  var schema = new mongoose.Schema(options.schema);
  for (key in options.self) {
    if (typeof options.self[key] !== 'function') continue;
    schema.statics[key] = options.self[key];
  }
  for (key in options) {
    if (typeof options[key] !== 'function') continue;
    schema.methods[key] = options[key];
  }
  return mongoose.model(name, schema);
};


// Define the model w/ pretty syntax!
var Animal = mongoose.createModel('Animal', {
  schema: {
    name: String,
    type: String
  },
  self: {
    findByType: function(type, cb) {
      return this.find({ type: type }, cb);
    }
  },
  findSimilarTypes: function(cb) {
    return this.model('Animal').find({ type: this.type }, cb);
  }
});


// Interaact with it
var dog = new Animal({ type: 'dog' });

dog.findSimilarTypes(function (err, dogs) {
  console.log(dogs); // woof
});

Animal.findByType('dog', function(err, dogs) {
  console.log(dogs); // ruff
});

Hi
your code is working great but I still try to understand why its not working for me in the standard way.
I will be happy to know what is the difference behind the scene. because I do not see any.
this is my code .
the error that I am getting is "findSimilarTypes is not a function"

let animalSchema = new mongoose.Schema({
  name: String,
  type: String
});
let Animal = mongoose.model("Animal", animalSchema);


animalSchema.statics.findByType = function(type, cb) {
  return this.find({ type: type }, cb);
};

animalSchema.methods.findSimilarTypes = function(cb) {
  return this.model("Animal").find({ type: this.type }, cb);
};
//invoke : 
dog.findSimilarTypes(function(err, dogs) {
  console.log(dogs); // woof
});

Animal.findByType("dog", function(err, dogs) {
  console.log(dogs); // ruff
});

Ok,
just find out my problem
the function should be added to the schema before creating the model