What's the best way to format/customize the remote response? - loopbackjs

Question

Sometimes, we need to modify the response JSON data before it be sent to client. for example:
//model definition
{
"name": "File",
"base": "PersistedModel",
"properties": {
"filename": {
"type": "string",
"required": true
},
"filepath": {
"type": "string"
}
}
"protected": ["filepath"]
}
I want to get a url property on GET /files/:id request, and so I defined a url GETTER on prototype.
//file.js
module.exports = function(File){
var baseUrl = 'http://example.com/uploads/files/';
File.prototype.__defineGetter__('url', function(){
return baseUrl + this.id.toString() + this.filename;
});
}
My question is How to expose the url property to remote response when I make a request as following?
GET /files/123456
expect a response like:
{
id: '123456',
filename: 'myfile.ext',
url: 'http://example.com/uploads/files/123456/myfile.ext'
}
Thanks a lot!

Answer 1

Use a remote method/hook and customize your response accordingly. See https://github.com/strongloop/loopback-example-app-logic/blob/master/common/models/car.js.

Answer 2

You can use Operation Hooks to intercept CRUD actions independently of the specific method that invoke them.
The code below will add the url property to the File object when loading a File object.
File.observe('loaded', function(ctx, next) {
var baseUrl = 'http://example.com/uploads/files/';
ctx.data.url = baseUrl + data.id + data.filename;
next();
});
This will get called when any of the methods below are invoked, either directly in your JS or indirectly via the HTTP API.
find()
findOne()
findById()
exists()
count()
create()
upsert() (same as updateOrCreate())
findOrCreate()
prototype.save()
prototype.updateAttributes()
Other Operation Hooks include:
access
before save
after save
before delete
after delete
loaded
persist