Created
May 3, 2017 16:28
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Explaining how Mongoose setters work
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| // dependencies | |
| let mongoose = require('mongoose') | |
| let Promise = require('bluebird') | |
| mongoose.Promise = Promise | |
| // connect to local db help | |
| mongoose.connect("mongodb://localhost/help") | |
| let db = mongoose.connection | |
| db.on('error', (err) => { | |
| return console.error('Connection error:', err) | |
| }) | |
| // define mongoose schema | |
| let fruitSchema = new mongoose.Schema({ | |
| kind: { | |
| type: String, | |
| // below function is called every time a new value to this property is assigned | |
| set: function (input) { | |
| if (this.kind) { | |
| // this.kind is defined, don't change it | |
| console.warn('You cannot override the value of apple.kind.') | |
| return this.kind | |
| } else { | |
| // this.kind was not defined yet, use the input as value | |
| return input | |
| } | |
| } | |
| } | |
| }) | |
| // create Fruit model | |
| let Fruit = mongoose.model('Fruit', fruitSchema) | |
| console.log("creating doc...") | |
| let apple = new Fruit({ | |
| // initialization: doc will take this value because right now kind is undefined | |
| kind: "apple" | |
| }) | |
| apple.save() | |
| .then((apple) => { | |
| // try to override apple, doesn't work, warning thrown | |
| console.log("trying to override...") | |
| apple.kind = "strawberry" | |
| return apple.save() | |
| }) | |
| .then((apple) => { | |
| console.log("Final value: " + apple.kind) | |
| }) | |
| .catch((error) => { | |
| console.error(error) | |
| }) | |
| // NOTE: a property's set function appears to be called every time that property gets assigned a new value, | |
| // not upon saving the doc like I claimed before. |
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| { | |
| "name": "help", | |
| "version": "1.0.0", | |
| "description": "", | |
| "main": "help.js", | |
| "scripts": { | |
| "test": "echo \"Error: no test specified\" && exit 1" | |
| }, | |
| "author": "", | |
| "license": "ISC", | |
| "dependencies": { | |
| "bluebird": "^3.5.0", | |
| "mongoose": "^4.9.7" | |
| } | |
| } |
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