Factor FK constraint logic out into a helper function

lib/associations/belongs-to.js

 var Utils     = require("./../utils")
   , DataTypes = require('./../data-types')
+  , Helpers   = require('./helpers')
 
 module.exports = (function() {
   var BelongsTo = function(srcDAO, targetDAO, options) {
@@ -24,18 +25,7 @@ module.exports = (function() {
 
     this.identifier = this.options.foreignKey || Utils._.underscoredIf(Utils.singularize(this.target.tableName) + "Id", this.source.options.underscored)
     newAttributes[this.identifier] = { type: DataTypes.INTEGER }
-
-    if(this.options.foreignKeyConstraint || this.options.onDelete || this.options.onUpdate) {
-      var primaryKeys = Utils._.filter(Utils._.keys(this.target.rawAttributes), function(key) { return this.target.rawAttributes[key].primaryKey }, this)
-
-        if(primaryKeys.length == 1) { // composite keys not supported with this approach
-          newAttributes[this.identifier].references = this.target.tableName,
-          newAttributes[this.identifier].referencesKey = primaryKeys[0]
-          newAttributes[this.identifier].onDelete = this.options.onDelete,
-          newAttributes[this.identifier].onUpdate = this.options.onUpdate
-        }
-    }
-
+    Helpers.addForeignKeyConstraints(newAttributes[this.identifier], this.target, this.source, this.options)
     Utils._.defaults(this.source.rawAttributes, newAttributes)
 
     // Sync attributes to DAO proto each time a new assoc is added

lib/associations/has-many.js

 var Utils     = require("./../utils")
   , DataTypes = require('./../data-types')
+  , Helpers   = require('./helpers')
 
 var HasManySingleLinked = require("./has-many-single-linked")
   , HasManyMultiLinked  = require("./has-many-double-linked")
@@ -65,18 +66,7 @@ module.exports = (function() {
     } else {
       var newAttributes = {}
       newAttributes[this.identifier] = { type: DataTypes.INTEGER }
-
-      if(this.options.foreignKeyConstraint || this.options.onDelete || this.options.onUpdate) {
-        var primaryKeys = Utils._.filter(Utils._.keys(this.source.rawAttributes), function(key) { return this.source.rawAttributes[key].primaryKey }, this)
-
-        if(primaryKeys.length == 1) { // composite keys not supported with this approach
-          newAttributes[this.identifier].references = this.source.tableName
-          newAttributes[this.identifier].referencesKey = primaryKeys[0]
-          newAttributes[this.identifier].onDelete = this.options.onDelete
-          newAttributes[this.identifier].onUpdate = this.options.onUpdate
-        }
-      }
-
+      Helpers.addForeignKeyConstraints(newAttributes[this.identifier], this.source, this.target, this.options)
       Utils._.defaults(this.target.rawAttributes, newAttributes)
     }
 

lib/associations/has-one.js

 var Utils     = require("./../utils")
   , DataTypes = require('./../data-types')
+  , Helpers   = require("./helpers")
 
 module.exports = (function() {
   var HasOne = function(srcDAO, targetDAO, options) {
@@ -29,18 +30,7 @@ module.exports = (function() {
 
     this.identifier = this.options.foreignKey || Utils._.underscoredIf(Utils.singularize(this.source.tableName) + "Id", this.options.underscored)
     newAttributes[this.identifier] = { type: DataTypes.INTEGER }
-
-    if(this.options.foreignKeyConstraint || this.options.onDelete || this.options.onUpdate) {
-      var primaryKeys = Utils._.filter(Utils._.keys(this.source.rawAttributes), function(key) { return this.source.rawAttributes[key].primaryKey }, this)
-
-        if(primaryKeys.length == 1) { // composite keys not supported with this approach
-        newAttributes[this.identifier].references = this.source.tableName,
-        newAttributes[this.identifier].referencesKey = primaryKeys[0]
-        newAttributes[this.identifier].onDelete = this.options.onDelete,
-        newAttributes[this.identifier].onUpdate = this.options.onUpdate
-      }
-    }
-
+    Helpers.addForeignKeyConstraints(newAttributes[this.identifier], this.source, this.target, this.options)
     Utils._.defaults(this.target.rawAttributes, newAttributes)
 
     // Sync attributes to DAO proto each time a new assoc is added

lib/associations/helpers.js

+var Utils = require("./../utils")
+
+module.exports = {
+
+  addForeignKeyConstraints: function(newAttribute, source, target, options) {
+    // FK constraints are opt-in: users must either rset `foreignKeyConstraints`
+    // on the association, or request an `onDelete` or `onUpdate` behaviour
+
+    if(options.foreignKeyConstraint || options.onDelete || options.onUpdate) {
+
+      // Find primary keys: composite keys not supported with this approach
+      var primaryKeys = Utils._.filter(Utils._.keys(source.rawAttributes), function(key) {
+        return source.rawAttributes[key].primaryKey
+      })
+
+      if(primaryKeys.length == 1) {
+        newAttribute.references = source.tableName,
+        newAttribute.referencesKey = primaryKeys[0]
+        newAttribute.onDelete = options.onDelete,
+        newAttribute.onUpdate = options.onUpdate
+      }
+    }
+  }
+
+}