Handle null vals properly

When converting null values
to database column values,
return null if column is
nullable, otherwise try
to cast it to the property
type, and if not, return
'null'.

lib/mysql.js

@@ -331,12 +331,26 @@ MySQL.prototype.getInsertedId = function(model, info) {
  * @returns {*} The escaped value of DB column
  */
 MySQL.prototype.toColumnValue = function(prop, val) {
-  if (val == null) {
+  if (val === undefined && this.isNullable(prop)) {
-    if (prop.autoIncrement || prop.id) {
-      return new ParameterizedSQL('DEFAULT');
-    }
     return null;
   }
+  if (val === null) {
+    if (this.isNullable(prop)) {
+      return val;
+    } else {
+      try {
+        var castNull = prop.type(val);
+        if (prop.type === Object) {
+          return JSON.stringify(castNull);
+        }
+        return castNull;
+      } catch (err) {
+        //if we can't coerce null to a certain type,
+        //we just return it
+        return 'null';
+      }
+    }
+  }
   if (!prop) {
     return val;
   }

test/mysql.test.js

@@ -6,7 +6,7 @@
 'use strict';
 var should = require('./init.js');
 
-var Post, PostWithStringId, PostWithUniqueTitle, db;
+var Post, PostWithStringId, PostWithUniqueTitle, PostWithNumId, db;
 
 // Mock up mongodb ObjectID
 function ObjectID(id) {
@@ -41,13 +41,22 @@ describe('mysql', function() {
       title: {type: String, length: 255, index: true},
       content: {type: String},
     });
-
+    PostWithNumId = db.define('PostWithNumId', {
+      id: {type: Number, id: true, null: false},
+      title: {type: String, length: 255, null: false, index: true},
+      content: {type: String, null: false},
+      buffProp: {type: Buffer, null: false},
+      objProp: {type: Object, null: false},
+      arrProp: {type: [Number], null: false},
+      dateProp: {type: Date, null: false},
+      pointProp: {type: 'GeoPoint', null: false},
+    });
     PostWithUniqueTitle = db.define('PostWithUniqueTitle', {
       title: {type: String, length: 255, index: {unique: true}},
       content: {type: String},
     });
 
-    db.automigrate(['PostWithDefaultId', 'PostWithStringId', 'PostWithUniqueTitle'], function(err) {
+    db.automigrate(['PostWithDefaultId', 'PostWithStringId', 'PostWithUniqueTitle', 'PostWithNumId'], function(err) {
       should.not.exist(err);
       done(err);
     });
@@ -56,9 +65,7 @@ describe('mysql', function() {
   beforeEach(function(done) {
     Post.destroyAll(function() {
       PostWithStringId.destroyAll(function() {
-        PostWithUniqueTitle.destroyAll(function() {
+        PostWithUniqueTitle.destroyAll(done);
-          done();
-        });
       });
     });
   });
@@ -424,6 +431,96 @@ describe('mysql', function() {
       });
     });
   });
+  context('null vals in different operators', function() {
+    var defaultPost = {
+      id: 3,
+      title: 'defTitle',
+      content: 'defContent',
+      buffProp: new Buffer('defBuffer'),
+      objProp: {defKey: 'defVal'},
+      arrProp: [0],
+      dateProp: new Date('2017-06-14'),
+      pointProp: {lng: 4.51515, lat: 57.2314},
+    };
+    beforeEach(function(done) {
+      PostWithNumId.destroyAll(done);
+    });
+    after(function(done) {
+      PostWithNumId.destroyAll(done);
+    });
+    it('should handle null in inq operator', function(done) {
+      defaultPost.id = 1;
+      defaultPost.title = 'Foo';
+      defaultPost.content = 'Bar';
+      PostWithNumId.create(defaultPost, function(err, post) {
+        should.not.exist(err);
+        post.id.should.equal(defaultPost.id);
+        PostWithNumId.find({where: {id: {inq: [null, 1]}}}, function(err, posts) {
+          should.not.exist(err);
+          posts.length.should.equal(1);
+          posts[0].title.should.equal('Foo');
+          posts[0].id.should.equal(1);
+          done();
+        });
+      });
+    });
+
+    it('should handle null in nin operator', function(done) {
+      defaultPost.id = 2;
+      defaultPost.title = 'Make';
+      defaultPost.content = 'Toyota';
+      PostWithNumId.create(defaultPost, function(err, post) {
+        should.not.exist(err);
+        post.id.should.equal(defaultPost.id);
+        PostWithNumId.find({where: {id: {nin: [null, 3]}}}, function(err, posts) {
+          should.not.exist(err);
+          posts.length.should.equal(1);
+          posts[0].content.should.equal('Toyota');
+          posts[0].id.should.equal(2);
+          done();
+        });
+      });
+    });
+
+    it('should handle null in neq operator', function(done) {
+      defaultPost.id = 3;
+      defaultPost.title = 'Model';
+      defaultPost.content = 'Corolla';
+      PostWithNumId.create(defaultPost, function(err, post) {
+        should.not.exist(err);
+        post.id.should.equal(defaultPost.id);
+        PostWithNumId.find({where: {id: {neq: null}}}, function(err, posts) {
+          should.not.exist(err);
+          posts.length.should.equal(1);
+          posts[0].content.should.equal('Corolla');
+          posts[0].id.should.equal(3);
+          done();
+        });
+      });
+    });
+
+    it('should handle null in nin op for different datatypes', function(done) {
+      PostWithNumId.create(defaultPost, function(err, post) {
+        should.not.exist(err);
+        post.id.should.equal(defaultPost.id);
+        PostWithNumId.find({where: {and: [
+        {id: {nin: [null]}},
+        {title: {nin: [null]}},
+        {content: {nin: [null]}},
+        {buffProp: {nin: [null]}},
+        {objProp: {nin: [null]}},
+        {arrProp: {nin: [null]}},
+        {dateProp: {nin: [null]}},
+        {pointProp: {nin: [null]}},
+        ]}}, function(err, posts) {
+          should.not.exist(err);
+          posts.length.should.equal(1);
+          posts[0].toObject().should.deepEqual(defaultPost);
+          done();
+        });
+      });
+    });
+  });
 
   // The where object should be parsed by the connector
   it('should support where for count', function(done) {