allow array syntax inside of the messageKey property of a config item

dev/config.js

@@ -77,6 +77,18 @@ module.exports = [
         "label": "This is a Toggle",
         "defaultValue": false
       },
+      {
+        "type": "toggle",
+        "messageKey": "arrayToggle[0]",
+        "label": "This is a Toggle",
+        "defaultValue": false
+      },
+      {
+        "type": "toggle",
+        "messageKey": "arrayToggle[1]",
+        "label": "This is a Toggle",
+        "defaultValue": false
+      },
       {
         "type": "color",
         "messageKey": "colorTest",

index.js

@@ -265,9 +265,8 @@ Clay.prepareForAppMessage = function(val) {
 
   if (Array.isArray(val)) {
     result = [];
-    val.forEach(function(item) {
-      var itemConverted = Clay.prepareForAppMessage(item);
-      result.push(itemConverted);
+    val.forEach(function(item, index) {
+      result[index] = Clay.prepareForAppMessage(item);
     });
   } else if (typeof val === 'object' && val) {
     if (typeof val.value === 'number') {
@@ -297,20 +296,54 @@ Clay.prepareForAppMessage = function(val) {
  * assign arrays into individual keys
  * @see {prepareForAppMessage}
  * @param {Object} settings
- * @param {Object} messageKeys
  * @returns {{}}
  */
-Clay.prepareSettingsForAppMessage = function(settings, messageKeys) {
-  var result = {};
+Clay.prepareSettingsForAppMessage = function(settings) {
+
+  // flatten settings
+  var flatSettings = {};
   Object.keys(settings).forEach(function(key) {
+    var val = settings[key];
+    var matches = key.match(/(.+?)(?:\[(\d*)\])?$/);
+
+    if (!matches[2]) {
+      flatSettings[key] = val;
+      return;
+    }
+
+    var position = parseInt(matches[2] || 0, 10);
+    key = matches[1];
+
+    if (typeof flatSettings[key] === 'undefined') {
+      flatSettings[key] = [];
+    }
+
+    flatSettings[key][position] = val;
+  });
+
+  var result = {};
+  Object.keys(flatSettings).forEach(function(key) {
     var messageKey = messageKeys[key];
-    var settingArr = Clay.prepareForAppMessage(settings[key]);
+    var settingArr = Clay.prepareForAppMessage(flatSettings[key]);
     settingArr = Array.isArray(settingArr) ? settingArr : [settingArr];
 
     settingArr.forEach(function(setting, index) {
+      if (typeof setting !== 'undefined') {
         result[messageKey + index] = setting;
+      }
     });
   });
+
+  // validate the settings
+  Object.keys(result).forEach(function(key) {
+    if (Array.isArray(result[key])) {
+      throw new Error('Clay does not support 2 dimensional arrays for item ' +
+                      'values. Make sure you are not attempting to use array ' +
+                      'syntax (eg: "myMessageKey[2]") in the messageKey for ' +
+                      'components that return an array, such as a checkboxgroup');
+    }
+  });
+
   return result;
 };
 

test/fixture.js

@@ -172,7 +172,9 @@ module.exports.messageKeysExpected = function(expected) {
   Object.keys(expected).forEach(function(key) {
     var expectedVal = Array.isArray(expected[key]) ? expected[key] : [expected[key]];
     expectedVal.forEach(function(val, index) {
+      if (typeof val !== 'undefined') {
         result[messageKeys[key] + index] = val;
+      }
     });
   });
 

test/spec/index.js

@@ -523,24 +523,21 @@ describe('Clay', function() {
         precision: undefined
       }), 12);
     });
+
+    it('Handles sparse arrays', function() {
+      var sparseArr = [];
+      sparseArr[1] = 'two';
+      sparseArr[2] = 'three';
+      assert.deepEqual(Clay.prepareForAppMessage(sparseArr), sparseArr);
+    });
   });
 
   describe('.prepareSettingsForAppMessage', function() {
     it('converts the settings correctly', function() {
-      var messageKeys = fixture.messageKeys([
-        'test1',
-        'test2',
-        'test3',
-        'test4[2]',
-        'test5',
-        'test6[4]',
-        'test7[3]',
-        'test8'
-      ]);
-
       var settings = {
         test1: false,
-        test2: 'val-2',
+        'test2[0]': 'val-1',
+        'test2[1]': 'val-2',
         test3: true,
         test4: ['cb-1', 'cb-3'],
         test5: 12345,
@@ -549,22 +546,39 @@ describe('Clay', function() {
         test8: {
           precision: 2,
           value: 12.34
-        }
+        },
+        'test9[1]': 'foo'
       };
 
-      var expected = fixture.messageKeysExpected({
+      var expected = {
         test1: 0,
-        test2: 'val-2',
+        test2: ['val-1', 'val-2'],
         test3: 1,
         test4: ['cb-1', 'cb-3'],
         test5: 12345,
         test6: [1, 2, 3, 4],
         test7: [1, 0, 1],
-        test8: 1234
+        test8: 1234,
+        test9: [undefined, 'foo']
+      };
+
+      stubMessageKeys(fixture.messageKeysObjToArray(expected));
+
+      var result = Clay.prepareSettingsForAppMessage(settings);
+
+      assert.deepEqual(result, fixture.messageKeysExpected(expected));
     });
 
-      var result = Clay.prepareSettingsForAppMessage(settings, messageKeys);
-      assert.deepEqual(result, expected);
+    it('throws if a 2 dimension array is present', function() {
+      var settings = {
+        'test1[1]': ['bad', 'developer!']
+      };
+
+      stubMessageKeys(['test1[2]']);
+
+      assert.throws(function() {
+        Clay.prepareSettingsForAppMessage(settings);
+      }, /2 dimensional array/i);
     });
   });
 });