Mongoose Plugin

What We Will Cover
Plug-ins
Middleware
Hooks
Discriminators
Promises

Main Take-away
– MongoDB is “schema-less”
– Everything in Mongoose starts with a Schema

Schema
– Defines the model “shape”

// Standup Model
var mongoose = require( 'mongoose' );
var Schema = mongoose.Schema;
var standupSchema = new Schema({
  memberName: {
  type: String,
  required: true,
  default: 'Mark'
    },
    // abbreviated for brevity...
  });

// child address schema...
var addressSchema = new Schema({
  type: String,
  street: String,
  city: String,
  state: String,
  country: String,
  postalCode: Number
  });
// parent customer schema...
var customerSchema = new Schema({
  name: {
  first: String,
  last: String
      },
  address: [ addressSchema ],
  createdOn: { type: Date, default: Date.now  },
  isActive: { type: Boolean, default: true }
  });

  // Start with the Schema
var personSchema = new Schema({
    firstName: String,
    lastName: String
  });
  // Build a model from the customer schema...
  var Person = mongoose.model(‘Person’, personSchema);
  // Create a document from the model
  var bob = new Person({
    firstName: ‘Bob’,
    lastName: ‘Doe’
  });

var query = { name: ‘old name’ };
var updates = { name: ‘new name’ };
var options = { new: false };
Person.findOneAndUpdate(query, updates, options, callback)

findOneAndUpdate – Mongoose Version 3.x
To return the original document rather than the updated document… set the option
“new” to false.
Defaults to true.

#“new: bool – if true, return the modified document rather than the original. defaults to false (changed in 4.0)”

Mongoose Validation :

 var schema = new Schema({
    itemName: {
    type: String,
    required: true
    }
  });

Query
– .then(…)
Mongoose 3
– To get promise… first call .exec()
– Person.find({ }).exec().then(…);
Mongoose 4
– Queries returned by .find() are promises
– Person.find({}).then(…);

Semantic versioning :

Given a version number MAJOR.MINOR.PATCH, increment the:
MAJOR – version when you make incompatible API changes,
.MINOR – version when you add functionality in a backwards-compatible manner, and
.PATCH – version when you make backwards-compatible bug fixes.

Schema Improvement – Options :

  var mongoose = require('mongoose')
  var pizzaSchema = new mongoose.schema(
  {
    size:string,....
  },
  { strict: false }
  ) //false: allow to save
    
  var pizza = mongoose.model('Pizza', pizzaSchema)   
  var takenAndBakePizza = new Pizza({isTakenAndBake: true})
  takenAndBakePizza.save()

  var Pizza = mongoose.model('Pizza', pizzaSchema)
  Pizza.findOneAndUpdate({_id: ___},{isTakeAndBake: false}, function(error) {...})

  //Validation array of Objects
  var pizzaSchema = new mongoose.Schema({
    validate: {
      validator: function(val) { return val.length > 1}
    }
  })

Middleware 4 –
1.Query Middleware – Methods [count, find, findOne, findOneAndUpdate, findOneAndRemove, insertMany, update]
2.Document Middleware – Methods [init, validate, save, remove]

https://github.com/Automattic/mongoose/wiki
https://mongoosejs.com/docs/guide.html#safe (v5.10.3)

Extending Functionality with Plugins
1.Custom Plug-in : Building your own plug-in Applying it to the Schema
2.Mongoose Plug-in Library : npm repository Plug-ins shared by other developers

1.Custom Plug-in :

a.Item Model “item.model.js”

var mongoose = require('mongoose');
var updatedOn = require('../plugins/updatedOn');
var valueIndicator = require('../plugins/valueIndicator');

var itemSchema = mongoose.Schema({
    name: String,
    description: String,
    category: String,
    estvalue: Number
},
    { strict: false }
);

itemSchema.plugin(updatedOn);
itemSchema.plugin(valueIndicator);

var Item = mongoose.model('Item', itemSchema);
// Custom validator
Item.schema.path('estvalue').validate(function (value) {
    return value > 0;
}, 'Estimated value must be greater than 0!');

module.exports = Item;

b.”valueIndicator.js”

var plugin = function valueIndicatorPlugin (schema) {
    schema.post('find', function (result) {
        result.forEach(function(element) {
            if (element.estvalue >= 100)
                element.description += ' ($)';
        }, this);
    });
}

module.exports = plugin;

c. “updateOn.js”

var plugin = function updatedOnPlugin (schema, options) {
    schema.add({ updatedOn: Date })

    schema.pre('save', function (next) {
         this.updatedOn = new Date;
        next();
    })

    if (options && options.index) {
         schema.path('updatedOn').index(options.index)
    }
}

module.exports = plugin;

“pre” Hook Plug-in : Save()
“post” Hook Plug-in : find()/findOne()

https://mongoosejs.com/docs/4.x/docs/validation.html