fix some foreign key cases

lib/associations/belongs-to.js

@@ -22,7 +22,10 @@ module.exports = (function() {
 
     if (!this.options.foreignKey) {
       this.options.foreignKey = Utils._.camelizeIf(
-        [this.as, this.target.primaryKeyAttribute].join("_"),
+        [
+          Utils._.underscoredIf(this.as, this.source.options.underscored),
+          this.target.primaryKeyAttribute
+        ].join("_"),
         !this.source.options.underscored
       )
     }

lib/associations/has-one.js

@@ -21,7 +21,10 @@ module.exports = (function() {
 
     if (!this.options.foreignKey) {
       this.options.foreignKey = Utils._.camelizeIf(
-        [this.source.name, this.source.primaryKeyAttribute].join("_"),
+        [
+          Utils._.underscoredIf(this.source.name, this.target.options.underscored),
+          this.source.primaryKeyAttribute
+        ].join("_"),
         !this.source.options.underscored
       )
     }

test/associations/belongs-to.test.js

@@ -238,7 +238,26 @@ describe(Support.getTestDialectTeaser("BelongsTo"), function() {
     })
   })
 
-  describe("Foreign key constraints", function() {
+  describe("foreign key", function () {
+    it('should lowercase foreign keys when using underscored', function () {
+      var User  = this.sequelize.define('User', { username: Sequelize.STRING }, { underscored: true })
+        , Account = this.sequelize.define('Account', { name: Sequelize.STRING }, { underscored: true })
+
+      User.belongsTo(Account)
+
+      expect(User.rawAttributes.account_id).to.exist;
+    });
+    it('should use model name when using camelcase', function () {
+      var User  = this.sequelize.define('User', { username: Sequelize.STRING }, { underscored: false })
+        , Account = this.sequelize.define('Account', { name: Sequelize.STRING }, { underscored: false })
+
+      User.belongsTo(Account)
+
+      expect(User.rawAttributes.AccountId).to.exist;
+    });
+  });
+
+  describe("foreign key constraints", function() {
     it("are not enabled by default", function(done) {
       var Task = this.sequelize.define('Task', { title: DataTypes.STRING })
         , User = this.sequelize.define('User', { username: DataTypes.STRING })

test/associations/has-one.test.js

@@ -211,7 +211,26 @@ describe(Support.getTestDialectTeaser("HasOne"), function() {
     })
   })
 
-  describe("Foreign key constraints", function() {
+  describe("foreign key", function () {
+    it('should lowercase foreign keys when using underscored', function () {
+      var User  = this.sequelize.define('User', { username: Sequelize.STRING }, { underscored: true })
+        , Account = this.sequelize.define('Account', { name: Sequelize.STRING }, { underscored: true })
+
+      Account.hasOne(User)
+
+      expect(User.rawAttributes.account_id).to.exist
+    })
+    it('should use model name when using camelcase', function () {
+      var User  = this.sequelize.define('User', { username: Sequelize.STRING }, { underscored: false })
+        , Account = this.sequelize.define('Account', { name: Sequelize.STRING }, { underscored: false })
+
+      Account.hasOne(User)
+
+      expect(User.rawAttributes.AccountId).to.exist
+    })
+  })
+
+  describe("foreign key constraints", function() {
     it("are not enabled by default", function(done) {
       var Task = this.sequelize.define('Task', { title: Sequelize.STRING })
         , User = this.sequelize.define('User', { username: Sequelize.STRING })