Modify loopback model before returning to client

Question

I have a ServerFile model which stores various pieces of information about an uploaded file.

{
 ....
 filename: 'blah.jpeg',
 container: 'images',
 size: 123654,
 ...
}

I would like to return a dynamically url property with the object, without storing it in a database.

{
 ....
 filename: 'blah.jpeg',
 container: 'images',
 size: 123654,
 ...
 url: 'uploads/images/blah.jpeg'
}

How would I go about doing this?

Answer 1

In your common/models/server-file.js file add a remote hook on find.

module.exports = function(ServerFile) {
....
ServerFile.afterRemote('find', function(ctx, modelInstance, next) {
    if (ctx.result) {
      if (Array.isArray(ctx.result)) {
        ctx.result.forEach(function(result) {
          result.url = new String(result.constructUrl());
        });
      } else {
        result.url = new String(result.constructUrl());
      }
    }
    next();
  });

Additionally, if you wished to remove an attribute before sending it back you can use

result.unsetAttribute('password')