Do not apply default values on data from database

Before this change, when a property was configured with a default value
at LoopBack side and the database was returned a record with a missing
value for such property, then we would supply use the configured
default.

This behavior is problematic for reasons explained in #1692.

In this commit, we are fixing DAO operations like `find` and
`findOrCreate` so that they do NOT apply default property values on
data returned by the database (connector).

Please note that most of the other CRUD methods were already not
applying default values on database data as long as the connector
provided native implementation of the operation.

lib/dao.js

@@ -1109,8 +1109,14 @@ DataAccessObject.findOrCreate = function findOrCreate(query, data, options, cb)
         let obj;
 
         if (data) {
-          obj = new Model(data, {fields: query.fields, applySetters: false,
-            persisted: true});
+          const ctorOpts = {
+            fields: query.fields,
+            applySetters: false,
+            persisted: true,
+            // see https://github.com/strongloop/loopback-datasource-juggler/issues/1692
+            applyDefaultValues: false,
+          };
+          obj = new Model(data, ctorOpts);
         }
 
         if (created) {
@@ -1631,6 +1637,8 @@ DataAccessObject.find = function find(query, options, cb) {
             fields: query.fields,
             applySetters: false,
             persisted: true,
+            // see https://github.com/strongloop/loopback-datasource-juggler/issues/1692
+            applyDefaultValues: false,
           };
           let obj;
           try {

test/basic-querying.test.js

@@ -922,6 +922,30 @@ describe('basic-querying', function() {
           });
         });
     });
+
+    it('preserves empty values from the database', async () => {
+      // https://github.com/strongloop/loopback-datasource-juggler/issues/1692
+
+      // Initially, all Products were always active, no property was needed
+      const Product = db.define('Product', {name: String});
+
+      await db.automigrate('Product');
+      const created = await Product.create({name: 'Pen'});
+
+      // Later on, we decide to introduce `active` property
+      Product.defineProperty('active', {
+        type: Boolean,
+        default: false,
+      });
+
+      // And query existing data
+      const found = await Product.findOne();
+      found.toObject().should.eql({
+        id: created.id,
+        name: 'Pen',
+        active: undefined,
+      });
+    });
   });
 
   describe('count', function() {

test/defaults.test.js

@@ -34,13 +34,13 @@ describe('defaults', function() {
     });
   });
 
-  it('should apply defaults on read', function(done) {
+  it('should NOT apply defaults on read', function(done) {
     db.defineProperty('Server', 'host', {
       type: String,
       default: 'localhost',
     });
     Server.all(function(err, servers) {
-      (new String('localhost')).should.equal(servers[0].host);
+      should(servers[0].host).be.undefined();
       done();
     });
   });
@@ -49,10 +49,9 @@ describe('defaults', function() {
     Server.create({host: 'localhost', port: 8080}, function(err, s) {
       should.not.exist(err);
       s.port.should.equal(8080);
-      Server.find({fields: ['host']}, function(err, servers) {
-        servers[0].host.should.equal('localhost');
-        servers[0].should.have.property('host');
-        servers[0].should.have.property('port', undefined);
+      Server.findById(s.id, {fields: ['host']}, function(err, server) {
+        server.should.have.property('host', 'localhost');
+        server.should.have.property('port', undefined);
         done();
       });
     });

test/manipulation.test.js

@@ -981,6 +981,30 @@ describe('manipulation', function() {
         }
       );
     });
+
+    it('preserves empty values from the database', async () => {
+      // https://github.com/strongloop/loopback-datasource-juggler/issues/1692
+
+      // Initially, all Products were always active, no property was needed
+      const Product = db.define('Product', {name: String});
+
+      await db.automigrate('Product');
+      const created = await Product.create({name: 'Pen'});
+
+      // Later on, we decide to introduce `active` property
+      Product.defineProperty('active', {
+        type: Boolean,
+        default: false,
+      });
+
+      // And updateOrCreate an existing record
+      const found = await Product.updateOrCreate({id: created.id, name: 'updated'});
+      found.toObject().should.eql({
+        id: created.id,
+        name: 'updated',
+        active: undefined,
+      });
+    });
   });
 
   bdd.describeIf(connectorCapabilities.supportForceId !== false,
@@ -1619,6 +1643,30 @@ describe('manipulation', function() {
         })
         .catch(done);
     });
+
+    it('preserves empty values from the database', async () => {
+      // https://github.com/strongloop/loopback-datasource-juggler/issues/1692
+
+      // Initially, all Products were always active, no property was needed
+      const Product = db.define('Product', {name: String});
+
+      await db.automigrate('Product');
+      const created = await Product.create({name: 'Pen'});
+
+      // Later on, we decide to introduce `active` property
+      Product.defineProperty('active', {
+        type: Boolean,
+        default: false,
+      });
+
+      // And findOrCreate an existing record
+      const [found] = await Product.findOrCreate({id: created.id}, {name: 'updated'});
+      found.toObject().should.eql({
+        id: created.id,
+        name: 'Pen',
+        active: undefined,
+      });
+    });
   });
 
   describe('destroy', function() {
@@ -2563,6 +2611,30 @@ describe('manipulation', function() {
         });
       });
     });
+
+    it('preserves empty values from the database', async () => {
+      // https://github.com/strongloop/loopback-datasource-juggler/issues/1692
+
+      // Initially, all Products were always active, no property was needed
+      const Product = db.define('Product', {name: String});
+
+      await db.automigrate('Product');
+      const created = await Product.create({name: 'Pen'});
+
+      // Later on, we decide to introduce `active` property
+      Product.defineProperty('active', {
+        type: Boolean,
+        default: false,
+      });
+
+      // And upsertWithWhere an existing record
+      const found = await Product.upsertWithWhere({id: created.id}, {name: 'updated'});
+      found.toObject().should.eql({
+        id: created.id,
+        name: 'updated',
+        active: undefined,
+      });
+    });
   });
 });