Loopback Passport Component: keep UserIdentity in sync with UserCredentials

passport-user-credential.js

module.exports = function (PassportUserCredential) {

    /*
     * Check if credentials already exist for a given provider and external id
     * Enable this hook if credentials can be linked only once
     *
     * @param Loopback context object
     * @param next middleware function
     * */
    PassportUserCredential.observe('before save', function checkPassportUserCredentials(ctx, next){
        //new insert - see if it is used else where
        if(ctx.isNewInstance === true && ctx.instance){ //indicates a new insert
            var filter = {where: { provider: ctx.instance.provider, externalId: ctx.instance.externalId }};
            PassportUserCredential.findOne(filter, function(err, userCredential){
                if(err) return next(err);

                if(userCredential){
                    err = new Error('Credentials already linked');
                    err.code = 'Validation Error';
                    err.statusCode = 422;
                    return next(err);
                } else {
                    //allow proceed
                    return next();
                }
            });
        } else {
            // don't allow updates on provider and external ID
            if(ctx.instance){
                delete ctx.instance.externalId;
                delete ctx.instance.provider;
            } else if(ctx.data){
                delete ctx.data.externalId;
                delete ctx.data.provider;
            }
            next();
        }
    });

    /*
     * Keep user identities in sync after saving a user-credential
     * It checks if a UserIdentityModel with the same provider and external ID exists
     * It assumes that the providername of userIdentity has suffix `-login`and of userCredentials has suffix `-link`
     *
     * @param Loopback context object
     * @param next middleware function
     * */
    PassportUserCredential.observe('after save', function checkPassportUserIdentities(ctx, next){
        var data = JSON.parse(JSON.stringify(ctx.instance));

        data.provider = data.provider.replace('-link', '-login');
        delete data.id; // has to be auto-increment

        var PassportUserIdentity = PassportUserCredential.app.models.PassportUserIdentity;
        var filter = {where: { provider: data.provider, externalId: data.externalId }};
        PassportUserIdentity.findOrCreate(filter, data, next);
    });

};

passport-user-identity.js

module.exports = function (PassportUserIdentity) {

    /*
    * Keep user credentials in sync after saving a user-identity
    * It checks if a UserCredentialModel with the same provider and external ID exists for that user
    * It assumes that the providername of userIdentity has suffix `-login`and of userCredentials has suffix `-link`
    *
    * @param Loopback context object
    * @param next middleware function
    * */
    PassportUserIdentity.observe('after save', function checkPassportUserCredentials(ctx, next){
        var data = JSON.parse(JSON.stringify(ctx.instance));

        data.provider = data.provider.replace('-login', '-link');
        delete data.id; // has to be auto-increment

        var PassportUserCredential = PassportUserIdentity.app.models.PassportUserCredential;
        var filter = {where: { userId: data.userId, provider: data.provider, externalId: data.externalId }};
        PassportUserCredential.findOrCreate(filter, data, next);
    });
};

test.sync-credentials-and-identities.js

var app = require('../../server');
var assert = require('assert');
var loopback = require('loopback');

before(function changeDataSourceToMemory(done) {

    var db = app.dataSources.db;

    loopback.configureModel(loopback.getModel('PassportUserCredential'), {dataSource: db});
    loopback.configureModel(loopback.getModel('PassportUserIdentity'), {dataSource: db});
    loopback.configureModel(loopback.getModel('Person'), {dataSource: db});

    if (db.connected) {
        db.automigrate(addUser);
    } else {
        db.once('connected', function () {
            db.automigrate(addUser);
        });
    }

    function addUser() {
        app.models.Person.create({
            'id': 1,
            'name': 'John',
            'firstName': 'Doe',
            'created': new Date(),
            'gender': 'M',
            'type': 'teacher',
            'username': 'john-doe',
            'password': 'testme',
            'email': '[email protected]'
        }, done);
    }
});

describe('Sync credentials when adding identities', function () {

    var user;
    var loginProvider = 'google-login';
    var linkProvider = 'google-link';
    var dummyLoginData = {
        'provider': loginProvider,
        'authScheme': 'oAuth 2.0',
        'externalId': '1081943683967445545454654646465411',
        'profile': {'info': 'some-provider-info'},
        'credentials': {'accessToken': 'secret-token-from-google'}
    };
    var dummyLinkData = {
        'provider': linkProvider,
        'authScheme': 'oAuth 2.0',
        'externalId': '1081943683967445545454654646465411',
        'profile': {'info': 'some-provider-info'},
        'credentials': {'accessToken': 'secret-token-from-google'}
    };

    before(function (done) {
        app.models.Person.findOne({id: 1}, function (err, u) {
            if (err) return done(err);
            user = u;
            dummyLoginData.userId = user.id;
            done();
        });
    });

    describe('IDENTITIES', function(){
        describe('add new identity', function () {
            it('should add the identity and credentials', function (done) {
                addDataAndExpectOneIdentityAndCredential(dummyLoginData, app.models.PassportUserIdentity, done);
            });
        });

        //https://github.com/strongloop/loopback-component-passport/issues/131
        describe.skip('add existing identity', function () {
            it('should do nothing on both tables', function (done) {
                addDataAndExpectOneIdentityAndCredential(dummyLoginData, app.models.PassportUserIdentity, done);
            });
        });

        //https://github.com/strongloop/loopback-component-passport/issues/131
        describe.skip('add existing identity with no credentials yet', function () {
            it('should not add identity but add credentials', function (done) {
                app.models.PassportUserCredential.destroyAll({'provider': linkProvider}, function (err) {
                    if (err) return done(err);
                    addDataAndExpectOneIdentityAndCredential(dummyLoginData, app.models.PassportUserIdentity, done);
                });
            });
        });

        describe('add new identity with already existing credentials', function () {
            it('should add identity but not add credentials', function (done) {
                app.models.PassportUserIdentity.destroyAll({'provider': loginProvider}, function (err) {
                    if (err) return done(err);
                    addDataAndExpectOneIdentityAndCredential(dummyLoginData, app.models.PassportUserIdentity, done);
                });
            });
        });
    });

    describe('CREDENTIALS', function(){

        //reset tables
        before(function(done){
            app.models.PassportUserIdentity.destroyAll({'provider': loginProvider}, function (err) {
                if (err) return done(err);
                app.models.PassportUserCredential.destroyAll({'provider': linkProvider}, done);
            });
        });

        describe('add new credential', function () {
            it('should add the credential and identity', function (done) {
                addDataAndExpectOneIdentityAndCredential(dummyLinkData, app.models.PassportUserCredential, done);
            });
        });

        describe('add existing credential', function () {
            it('should fail and return a Validation error', function (done) {
                app.models.PassportUserCredential.create(dummyLinkData, function (err) {
                    if (!err) return done('it should fail');

                    assert.equal(err.code, 'Validation Error');
                    assert.equal(err.message, 'Credentials already linked');

                    app.models.PassportUserIdentity.find(
                        {externalId: dummyLinkData.externalId, provider: loginProvider},
                        function (err, identities) {
                            if (err) return done(err);
                            assert.equal(identities.length, 1);
                            //get credentials for this provider and externalId
                            app.models.PassportUserCredential.find(
                                {externalId: dummyLinkData.externalId, provider: linkProvider},
                                function (err, creds) {
                                    if (err) return done(err);
                                    assert.equal(creds.length, 1);
                                    done();
                                });
                        });
                });
            });
        });

        describe('add new credential with existing identity', function () {
            it('should fail and return a Validation error', function (done) {
                app.models.PassportUserCredential.destroyAll({'provider': linkProvider}, function (err) {
                    if (err) return done(err);
                    addDataAndExpectOneIdentityAndCredential(dummyLinkData, app.models.PassportUserCredential, done);
                });
            });
        });

    });



    function addDataAndExpectOneIdentityAndCredential(data, model, done) {
        model.create(data, function (err, inst) {
            if (err) return done(err);
            assert.equal(inst.provider, data.provider);
            assert.equal(inst.externalId, data.externalId);

            app.models.PassportUserIdentity.find(
                {externalId: data.externalId, provider: loginProvider},
                function (err, identities) {
                    if (err) return done(err);
                    assert.equal(identities.length, 1);
                    //get credentials for this provider and externalId
                    app.models.PassportUserCredential.find(
                        {externalId: data.externalId, provider: linkProvider},
                        function (err, creds) {
                            if (err) return done(err);
                            assert.equal(creds.length, 1);
                            done();
                        });
                });
        });
    }
});

Nice , I'll remember that trick.

It's strange however that you have an endless loop!
I purposely used findOrCreate, so the loop should stop once a model is found, because nothing gets saved then anymore

@ernie58 @lotas I can confirm the loop. skipAfterSave solves it.