I have not found an easy way to extend Mongoose Schema/Model methods because of the way that mongoose handles them, and because of the fact that mongoose=require('mongoose') is a singelton.
So, I am 'faking' class inheritance here:
'use strict';
var _ = require('lodash');
module.exports = function(MongooseModel, options) {
var Collection = {};
_.assign(Collection, _.toPlainObject(MongooseModel));
Collection.pluralName = Collection.modelName + 's';
Collection.foo = Collection.bar;
return Collection
};
Does anyone have a more elegant solution?
EDIT:
Turns out the above solution doesn't work. For instance, using Collection.find({}, function(err, docs) {...}) will error when Mongo tries to create "docs" from a model that has not been registered with Mongoose.
So, what I've done is now completely inelegant:
'use strict';
var _ = require('lodash');
module.exports = function(MongooseModel, options) {
var Collection = MongooseModel;
...
return Collection
};
There are some ways to try and do this, though not sure exactly what your trying to extend.
You can add instance methods <schema>.methods.<mymethod> = function(){}
// define a schema
var animalSchema = new Schema({ name: String, type: String });
// assign a function to the "methods" object of our animalSchema
animalSchema.methods.findSimilarTypes = function (cb) {
return this.model('Animal').find({ type: this.type }, cb);
}
And you can add static methods <schema>.statics.<mymethod> = function(){}
// assign a function to the "statics" object of our animalSchema
animalSchema.statics.findByName = function (name, cb) {
return this.find({ name: new RegExp(name, 'i') }, cb);
}
var Animal = mongoose.model('Animal', animalSchema);
Animal.findByName('fido', function (err, animals) {
console.log(animals);
});
Examples are from the mongoose docs - just search for "statics".
The statics functions you can call on a model. The methods are usually functions that work with an instance of a document returned from a query or created with new.
Related
Is there a way to store a document then get an updated value of it at a later date without needing to query and populate again?
const someDocument = await SomeModel.findOne({...}).populate(...);
// store a reference to it for use
const props = {
document: someDocument,
...
}
// at a later time
await props.document.getLatest() <-- update and populate in place?
As describe here,
You can define your own custom document instance methods by add functions on the schema level.
example taken from mongoose doc:
// define a schema
const animalSchema = new Schema({ name: String, type: String });
// assign a function to the "methods" object of our animalSchema
animalSchema.methods.findSimilarTypes = function(cb) {
return mongoose.model('Animal').find({ type: this.type }, cb);
};
const Animal = mongoose.model('Animal', animalSchema);
const dog = new Animal({ type: 'dog' });
dog.findSimilarTypes((err, dogs) => {
console.log(dogs); // woof
});
This is the only way I can think of doing what you want - add a function that populate.
another thing that might help: you can create a pre hook on 'find' and add populate in it
How do you call a function from within another function in a module.exports declaration?
I have MVC structure node js project and a controller called TestController.js. I want to access method within controller, but using this keyword gives below error:
cannot call method getName of undefined
"use strict"
module.exports = {
myName : function(req, res, next) {
// accessing method within controller
this.getName(data);
},
getName : function(data) {
// code
}
}
How do I access methods within controller?
I found the solution :-)
"use strict"
var self = module.exports = {
myName : function(req, res, next) {
// accessing method within controller
self.getName(data);
},
getName : function(data) {
// code
}
}
You can access the getName function trough module.exports. Like so:
"use strict"
module.exports = {
myName : function(req, res, next) {
// accessing method within controller
module.exports.getName(data);
},
getName : function(data) {
// code
}
}
Maybe you could do it like this. It reduce nesting. And all your export is done at the end of your file.
"use strict";
var _getName = function() {
return 'john';
};
var _myName = function() {
return _getName();
};
module.exports = {
getName : _getName,
myName : _myName
};
If you want to use the function locally AND in other files...
function myFunc(){
return 'got it'
}
module.exports.myFunc = myFunc;
I know the answer is already accepted, but I feel the need to add my two cents on the issue.
Node modules have a "Singletonic" nature, when inside the module, you are the module.
In my opinion, at least design pattern wise, inner module methods can be accessed more cleanly, without the need for this or a copy of self for that matter.
Using this, could be dangerous, if one happens to send the separate methods around and forgets to use .bind.
Using a copy of self, is redundant, we already are inside a Singleton behaving module, why keep a reference to yourself when you can avoid that?
Consider these instead:
Option 1
// using "exports."
exports.utilityMethod = (..args) => {
// do stuff with args
}
exports.doSomething = (someParam) => {
// this always refers to the module
// no matter what context you are in
exports.utility(someParam)
}
Option 2
// using module.exports
const utility = (..args) => {
// do stuff with args
}
const doSomething = (someParam) => {
// Inside the module, the utility method is available
// to all members
utility(someParam)
}
// either this
module.exports = {
utility,
doSomething,
}
// or
module.exports = {
customNameForUtility: utility,
customNameForDoSomething: doSomething
}
This works the same for es6 modules:
Option 1 (ES6)
export const utilityMethod = (..args) => {
// do stuff with args
}
export const doSomething = (someParam) => {
// this always refers to the module
// no matter what context you are in
utility(someParam)
}
Option 2 (ES6)
const utility = (..args) => {
// do stuff with args
}
const doSomething = (someParam) => {
// Inside the module, the utility method is available
// to all members
utility(someParam)
}
export default {
doSomething,
utility
}
// or
export {
doSomething,
utility
}
Again, this is just an opinion, but it looks cleaner, and is more consistent across different implementations, and not a single this/self is used.
The question:
As I understand in sails.js during initialization process Services are initialized before Models.
Is there any possibility to change this behavior? To make Models load before Services.
If it's not, then how can I load particular settings from the database to use them to build instance of my class described in some Service during this Service initialization?
A little bit code for solidity:
api/models/Model.js
console.log("Model Identified");
module.exports = {
attributes: {
name: { type: 'string', required: true, size: 15 },
//Some extra secret fields
}
};
...
api/services/MyCoolService.js
console.log('service inits');
function MyCoolService(options){
//some extraordinary constructor logic may be ommited
}
MyCoolService.prototype.setOptions = function(options){
//Set values for MyCoolService fields.
}
//Some other methods
var myCoolServiceWithSettingsFromDb = new MyCoolService();
//That's the place
model.findOne(sails.config.myApplication.settingsId).exec(function(err,result){
if(!err)
myCoolServiceWithSettingsFromDb.setOptions(result);
});
module.exports = myCoolServiceWithSettingsFromDb;
It's because you instantiate object in service with constructor that needs sails that not exist. Try use this at MyCoolService;
module.exports = {
someOption: null,
method: function () {
var that = this;
sails.models.model.findOne(sails.config.myApplication.settingsId)
.exec(function (err, result) {
if (!err)
that.someOption = result;
});
}
};
that method can be called by sails.services.mycoolservice.method() or simply MyCoolService.method() to give your service some option from DB.
If you want to initiate them at Sails start, call that method at config/bootstrap.js
Thanks to Andi Nugroho Dirgantara,
I ended up with this solution (I still don't like it much, but it works):
api/services/MyCoolService.js
console.log('service inits');
function MyCoolService(options){
//some extraordinary constructor logic may be ommited
}
//All the same as in question
//The instance
var instance;
module.exports = module.exports = {
init: function(options) {
instance = new MyCoolService(options);
},
get: function() {
return instance;
},
constructor: MyCoolService
};
config/bootstrap.js
...
Model.findOrCreate({ id: 1 }, sails.config.someDefaultSettings).exec(function(err, result) {
if (err)
return sails.log.error(err);
result = result || sails.config.someDefaultSettings;
MyCoolService.init(result);
return sails.log.verbose("MyCoolService Created: ", TbcPaymentProcessorService.get());
});
...
tests/unit/service/MyCoolService.test.js
...
describe('MyCoolService', function() {
it('check MyCoolService', function(done) {
assert.notDeepEqual(MyCoolService.get(), sails.config.someDefaultSettings);
done();
});
});
...
It works: the service is instantiated once while bootstraping and it's instance is avaliable everywhere.
But to me this solution still weird... I still don't understand how to globally instantiate instance of my service (for use in a lot of controllers) and make it the best way.
I'd like to add a default toDisplay function to all models which will use metadata, not unlike attribute/association definitions, to perform manipulations on the instance's attributes/associations making them suitable for display in the UI.
for example:
Foo.findOne(someId)
.exec(function(err, foo) {
...
res.view({
foo: foo.toDisplay(),
});
});
So, I'd like to add this function too all models. I can imagine a
Model.prototype.toDisplay = ...
solution, but I'm not sure where to get Model from (some long require('waterline/..../model') path?), and if I had Model, where to put that snip-it.
Please advise.
Model configuration is fully documented here on SailsJS.org. #umassthrower is correct in pointing out that adding an instance method to config/models.js would add it to all of your models; he's also correct in observing that this is not the intended use of the config file.
The reason you're finding this a bit more challenging in Sails than Rails is that Ruby has real classes and inheritance, and Javascript just has objects. One fairly clean way to simulate inheritance and extend your model objects from a "base" object would be to use something like Lodash's _.merge function. For example you could save your base model in lib/BaseModel.js:
// lib/BaseModel.js
module.exports = {
attributes: {
someAttribute: 'string',
someInstanceFunction: function() {
// do some amazing (synchronous) calculation here
}
}
};
Then in your model file, require lodash and use _.extend:
// api/models/MyModel.js
var _ = require('lodash');
var BaseModel = require("../../lib/BaseModel.js");
module.exports = _.merge({}, BaseModel, {
attributes: {
someOtherAttribute: 'integer'
}
};
The attributes from your base model will be merged with MyModel, with MyModel taking precedence.
Setting the first argument to the empty model {} is important here; _.merge is destructive for the first object sent in, so if you just did _.merge(BaseModel, {...} then the base model would be modified.
Also, remember to npm install lodash!
In Sails 0.x, when the moduleloader was loaded, you could access to sails.models directly, but now in 1.x this is not ready yet, so, my solution to this was creating a custom hook that wraps the loadModels function of sails.modules, this may not be the best solution but works for me #adam-pietrasiak hope this works for you too :) I am also super lazy when it comes to repeating code.
// provide this code in api/hooks/overrides.js or use another name, who cares
const _ = require('lodash');
module.exports = function (sails) {
return {
defaults: {},
savedModelLoad: null,
configure: function () {
this.savedModelLoad = this.savedModelLoad || sails.modules.loadModels;
sails.modules.loadModels = this.loadModelsAndApplyOverrides;
},
loadModelsAndApplyOverrides: function(cb){
this.savedModelLoad(function (err, models) {
const newModels = _.map(models, applyModelOverrides);
cb(err, newModels);
});
}
};
};
function applyModelOverrides(model) {
return _.merge(model, {
// do your custom stuff here
attributes: {
someAttribute: 'string',
someInstanceFunction: function() {
// do some amazing (synchronous) calculation here
}
}
});
}
Is there a way to add custom instance methods to a mongoose schema after it has already been "exported".
For example, if I have a schema:
module.exports = function(app, db, config) {
var MySchema = new Schema({ name: String });
MySchema.methods.doIt = function() { console.log("I DID IT!"); }
db.model("MySchema", MySchema);
}
Then I want to add new methods to the schema dynamically after it has already been loaded into the mongoose model object.
MySchema = db.model('MySchema');
var obj = new MySchema({name: "robocop"});
var myNewMethod = function() { console.log(this.name); }
// Do Magic here to add the myNewMethod to object.
obj.myNewMethod();
Did You Even Try?
I have already tried to just add it to the mongoose model object, however this produces errors saying the schema objects do not have the method I just added.
MySchema = db.model('MySchema');
MySchema.schema.methods.myNewMethod = function() { console.log(this.name); }
db.model('MySchema', MySchema);
console.log(MySchema.schema.methods); // This shows my method was added!
...
var obj = new MySchema({name: "robocop"});
obj.myNewMethod(); //ERROR: YOUR METHOD DOESN'T EXIST!
Caveat coder. It is possible, and whether or not it's a good idea is left as an exercise for the reader.
Your schema is of course affected by the schema object, not any particular instance of your model. Thus, if you want to modify the schema, you'll need to have access to the schema itself.
Here's an example:
var mongoose = require('mongoose')
, db = mongoose.connect("mongodb://localhost/sandbox_development")
var schema = new mongoose.Schema({
blurb: String
})
var model = mongoose.model('thing', schema)
var instance = new model({blurb: 'this is an instance!'})
instance.save(function(err) {
if (err) console.log("problem saving instance")
schema.add({other: String}) // teh secretz
var otherInstance = new model({blurb: 'and I am dynamic', other: 'i am new!'})
otherInstance.save(function(err) {
if (err) console.log("problem saving other instance", err)
process.exit(0)
})
})
Notice the call to schema.add which Schema calls internally when you make a new one.