How to include related entities in REST with loopback.io

Question

I'm using Strongloop's loopback tool to create a REST service. I'm wondering how to define what related entities to return when requesting a model.

I see in the docs that you can send a request like GET /api/members?filter[include]=posts and that will return the related post models, and I discovered that you can make a request like GET /api/members?filter[include]=posts&filter[include]=comments to get posts and comments, but is there a way to define either in code or the generated json file that you'd like a certain relation to always be returned when requesting a model?

Tobytobye

Answer 1

The preset filter properties are referred as default scope. We have a pending pull request to support that. Please see https://github.com/strongloop/loopback-datasource-juggler/pull/296.

As a workaround before the feature is released, you can use beforeRemote hooks to update the filter object with your default scope. See http://docs.strongloop.com/display/LB/Defining+remote+hooks.

Lobel

Thanks for the info. Very excited about this project. – Tobytobye

The link is not valid anymore, but I am really curious about how to override filter in a beforeRemote, any hints? – Glomerulus

Something like ctx.args.filter = {include: 'posts'}; in a beforeRemote does the trick – Glomerulus

Today the preset filters are support. Add this to your model.json file: "scope": { "include": { "relation": "channel", "scope": { "fields": ["code", "description"] } } }. Don't forget to add a belongsTo relation to the other model. And to the other model add a hasMany relation to this model. Raymond, maybe you can update your answer to reflect this. – Kiefer

Answer 2

You can use two different easy methods to get relationships to the account.

1. Using Model definitions in the Model.json file.

   "validations": [],
   "relations": {
     "team": {
     "type": "belongsTo",
     "model": "Team",
     "foreignKey": ""
   },
   "user": {
     "type": "belongsTo",
     "model": "User",
     "foreignKey": ""
   }
   }
   

This will always bind one model with another models using direct relationships and you can retrieve them using following code lines.

app.models.TeamRole.findOne({
      where: {
        userId: user.id
      },
      include:[ {
        relation: 'team'
      },
{
        relation: 'user'
      } ]
    },function(err,team,user){
//retrieve relational data here
});

2. You can use operational hooks concept to obtain such kinds of relations easily.

Cheers.

Deficit