Model that hasAndBelongsTo the same Model

[Julian Mayorga]

First of all I want to say thanks to everyone that supports Loopback, it's a pleasure to scaffold with Loopback robust, authenticated and documented APIs in node.js.

I have a question: How do you define in models.json that a Model has many instances of the same Model? e.g. I have an Organization model, and an Organization can have many Organizations as clients.

I tried to define a hasMany thorugh relationship, but it didn't work. For more details about my models.json that did not work take a look at my StackOverflow question http://stackoverflow.com/questions/24165151/how-to-define-that-a-model-has-many-of-the-same-model-in-strongloop-loopback.

Thanks so much in advance,

Julián Mayorga.

[Lee Driscoll]

I haven't tried this personally, but I recommend removing the properties from your client model as Loopback will automatically create these from the foreign keys in the relation configs

[Julian Mayorga]

Lee, I tried your suggestion but unfortunately it did not work.

I also tried defining the relationship in code as exemplified in the official docs http://docs.strongloop.com/display/DOC/Creating+model+relations#Creatingmodelrelations-hasManyThrough. Unfortunately I could not find anywhere how to make this relationship work using the same Model instead of two different ones. I ended up with the following code that also did not work:

  var loopback = require('loopback');                                      

  var app = require('../app');                                             

  var Organization = app.models.organization;                              

  var Client = app.models.client;                                          

      

  Client.belongsTo(Organization);                                          

        

  Organization.hasMany(Organization, {through: Client});

My models.json looks like this now:

"organization": {

    "properties": {

      "name": {

        "type": "string"

      }

    },

    "relations": {

      "users": {

        "type": "hasMany",

        "model": "user",

        "foreignKey": "organizationId"

      }

    },

    "dataSource": "mongodb",

    "public": true,

    "plural": "organizations"

  },

  "client": {

    "properties": {

      "organizationId": {

        "type": "number",

        "id": true

      },

  "clientId": {

        "type": "number",

        "id": true

      }

    },

    "dataSource": "mongodb",

    "public": true,

    "plural": "clients"

  }

Any kind of help to guide me in the right direction will be greatly appreciated.

Regards,

Julián.

[Lee Driscoll]

Still not sure about how to go through the Client model, but for having an Organization that can have many Organizations, the following works (just tested):

"organization": {
        "properties": {
            "name": {
                "type": "string"
            }
        },

        "options": {
            "relations": {
                "organizations": {
                    "type": "hasMany",
                    "model": "organization",
                    "foreignKey": "organizationId"
                },
                "organization": {
                    "type": "belongsTo",
                    "model": "organization",

                    "foreignKey": "organizationId"
                }
            }
        },
        "dataSource": "mongodb",
        "public": true,
        "plural": "organizations"
    },

Remember that the relations object needs to be inside the options object

[Raymond Feng]

Lee, you are right. Your example shows how to set up a hasMany/belongsTo relation to itself.

Thanks,

---

Raymond Feng

Co-Founder and Architect @ StrongLoop, Inc.

StrongLoop makes it easy to develop APIs in Node, plus get DevOps capabilities like monitoring, debugging and clustering.

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[Julian Mayorga]

That worked perfectly Lee, I am truly grateful. I did not know about the options object, thanks for pointing that out.

Many thanks for your time!

Julián.

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[Lee Driscoll]

No worries Juli án, I got to learn something too ;)

[Raymond Feng]

To really use a through model to relate to itself is a bit tricky. The following code works for me:

var loopback = require('loopback');

  var app = require('../app');

  var Organization = app.models.organization;

  var Client = app.models.client;

  Client.belongsTo(Organization, {as: 'client', foreignKey: 'clientId'});

  Client.belongsTo(Organization, {as: 'organization', foreignKey: 'organizationId'});

  Organization.hasMany(Organization, {through: Client, foreignKey: 'clientId'});

  Organization.create({name: 'marketing'}, function(err, org1) {

    org1.organizations.create({name: 'sales'}, function(err, org2) {

      Organization.find(function(err, orgs) {

        console.log('Organizations: %j', orgs);

      });

      Client.find(function(err, clients) {

        console.log('Clients: %j', clients);

      });

    });

  });

"organization": {

    "properties": {

      "name": {

        "type": "string"

      }

    },

    "relations": {

      "users": {

        "type": "hasMany",

        "model": "user",

        "foreignKey": "organizationId"

      }

    },

    "dataSource": "db",

    "public": true,

    "plural": "organizations"

  },

  "client": {

    "properties": {

      "organizationId": {

        "type": "number"

      },

  "clientId": {

        "type": "number"

      }

    },

    "dataSource": "db",

    "public": true,

    "plural": "clients"

  }

Thanks,

---

Raymond Feng

Co-Founder and Architect @ StrongLoop, Inc.

StrongLoop makes it easy to develop APIs in Node, plus get DevOps capabilities like monitoring, debugging and clustering.

[Jonathan Casarrubias]

Hello Raymond,

I have been trying to use your example but I'm unable to success, I hope you can help me get this through..

Case:

In my project, there are accounts that can sponsorship other accounts, so I need a relation Many to Many Through

I have 2 models

Account and AccountSponsor (Middle Model) and I have been trying using:

================== Boot Script =========================

var loopback = require('loopback');

module.exports = function(app) {

    var

    Account        = app.models.Account,

    AccountSponsor = app.models.AccountSponsor;

    

    AccountSponsor.belongsTo(Account, {as: 'sponsored', foreignKey: 'sponsoredId'});

    AccountSponsor.belongsTo(Account, {as: 'sponsor',   foreignKey: 'sponsorId'  });

    Account.hasMany(Account, {as: 'sponsored', through: AccountSponsor, foreignKey: 'sponsoredId'});

    Account.hasMany(Account, {as: 'sponsors',  through: AccountSponsor, foreignKey: 'sponsorId'});

   

    Account.create({

            "fullName" : "sponsored",

            "username" : "sponsored",

            "email"    : "spon...@sponsored.com",

            "password" : "sponsored"

    }, function(err, account){

   account.sponsors.create({

"fullName" : "sponsor",

"username" : "sponsor",

"email"    : "spo...@sponsor.com",

"password" : "sponsor"

}, function(err, response){

       console.log("SPONSOR: ", response);

});

});

};

=========================

But the relation is being incorrectly created

{

    "_id": {

        "$oid": "54979d81237056d6c0030936"

    },

    "sponsoredId": {

        "$oid": "54979d81237056d6c0030935"

    },

    "sponsorId": null

}

Both Accounts where created in the database but only 1 id is stored in the relation model. I tried using the CLI loopback:relation and I get the exact same error

I appreciate your help and support

John