From ad5beb83f6836390a9cfc1f95f073af973bcf6a4 Mon Sep 17 00:00:00 2001
From: Mark Bradley <barkmadley@gmail.com>
Date: Sat, 22 Oct 2011 14:42:33 +1100
Subject: [PATCH] added $index value in the binding context of foreach
 templates.

---
 spec/templatingBehaviors.js                         | 11 ++++++++++-
 src/binding/editDetection/arrayToDomNodeChildren.js | 10 +++++-----
 src/templating/templating.js                        | 12 +++++++-----
 3 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/spec/templatingBehaviors.js b/spec/templatingBehaviors.js
index 77281e8e6..588a579e6 100644
--- a/spec/templatingBehaviors.js
+++ b/spec/templatingBehaviors.js
@@ -350,6 +350,15 @@ describe('Templating', {
         ko.applyBindings({ myCollection: myArray }, testNode);
         value_of(testNode.childNodes[0]).should_contain_html("<div>the item is <span>bob</span></div><div>the item is <span>frank</span></div>");
     },    
+
+    'Data binding \'foreach\' option should apply bindings with an $index in the context': function () {
+        var myArray = new ko.observableArray([{ personName: "Bob" }, { personName: "Frank"}]);
+        ko.setTemplateEngine(new dummyTemplateEngine({ itemTemplate: "The item # is <span data-bind='text: $index'></span>" }));
+        testNode.innerHTML = "<div data-bind='template: { name: \"itemTemplate\", foreach: myCollection }'></div>";
+
+        ko.applyBindings({ myCollection: myArray }, testNode);
+        value_of(testNode.childNodes[0]).should_contain_html("<div>the item # is <span>0</span></div><div>the item # is <span>1</span></div>");
+    },
     
     'Data binding \'foreach\' option should update DOM nodes when a dependency of their mapping function changes': function() {
         var myObservable = new ko.observable("Steve");
@@ -650,4 +659,4 @@ describe('Templating', {
         ko.applyBindings({ someData: { childProp: 'abc' } }, testNode);
         value_of(testNode).should_contain_html("start <!-- ko template: { data: somedata } --><div>childprop: abc</div><!-- /ko -->end");
     }    
-})
\ No newline at end of file
+})
diff --git a/src/binding/editDetection/arrayToDomNodeChildren.js b/src/binding/editDetection/arrayToDomNodeChildren.js
index 6b1294aa3..ef2e48a3d 100644
--- a/src/binding/editDetection/arrayToDomNodeChildren.js
+++ b/src/binding/editDetection/arrayToDomNodeChildren.js
@@ -10,11 +10,11 @@
     // "callbackAfterAddingNodes" will be invoked after any "mapping"-generated nodes are inserted into the container node
     // You can use this, for example, to activate bindings on those nodes.
 
-    function mapNodeAndRefreshWhenChanged(containerNode, mapping, valueToMap, callbackAfterAddingNodes) {
+    function mapNodeAndRefreshWhenChanged(containerNode, mapping, valueToMap, callbackAfterAddingNodes, index) {
         // Map this array value inside a dependentObservable so we re-map when any dependency changes
         var mappedNodes = [];
         var dependentObservable = ko.dependentObservable(function() {
-            var newMappedNodes = mapping(valueToMap) || [];
+            var newMappedNodes = mapping(valueToMap, index) || [];
             
             // On subsequent evaluations, just replace the previously-inserted DOM nodes
             if (mappedNodes.length > 0) {
@@ -77,9 +77,9 @@
 
                 case "added": 
                     var valueToMap = editScript[i].value;
-                    var mapData = mapNodeAndRefreshWhenChanged(domNode, mapping, valueToMap, callbackAfterAddingNodes);
+                    var mapData = mapNodeAndRefreshWhenChanged(domNode, mapping, valueToMap, callbackAfterAddingNodes, i);
                     var mappedNodes = mapData.mappedNodes;
-                    
+
                     // On the first evaluation, insert the nodes at the current insertion point
                     newMappingResult.push({ arrayEntry: editScript[i].value, domNodes: mappedNodes, dependentObservable: mapData.dependentObservable });
                     for (var nodeIndex = 0, nodeIndexMax = mappedNodes.length; nodeIndex < nodeIndexMax; nodeIndex++) {
@@ -99,7 +99,7 @@
                         insertAfterNode = node;
                     } 
                     if (callbackAfterAddingNodes)
-                        callbackAfterAddingNodes(valueToMap, mappedNodes);
+                        callbackAfterAddingNodes(valueToMap, mappedNodes, i);
                     break;
             }
         }
diff --git a/src/templating/templating.js b/src/templating/templating.js
index 2d09395be..67ed903e1 100644
--- a/src/templating/templating.js
+++ b/src/templating/templating.js
@@ -117,8 +117,10 @@
     };
 
     ko.renderTemplateForEach = function (template, arrayOrObservableArray, options, targetNode, parentBindingContext) {   
-        var createInnerBindingContext = function(arrayValue) {
-            return parentBindingContext.createChildContext(ko.utils.unwrapObservable(arrayValue));
+        var createInnerBindingContext = function(arrayValue, index) {
+            var result = parentBindingContext.createChildContext(ko.utils.unwrapObservable(arrayValue));
+            result['$index'] = index;
+            return result;
         };
 
         // This will be called whenever setDomNodeChildrenFromArrayMapping has added nodes to targetNode
@@ -139,10 +141,10 @@
                 return options['includeDestroyed'] || !ko.utils.unwrapObservable(item['_destroy']);
             });
 
-            ko.utils.setDomNodeChildrenFromArrayMapping(targetNode, filteredArray, function (arrayValue) {
+            ko.utils.setDomNodeChildrenFromArrayMapping(targetNode, filteredArray, function (arrayValue, index) {
                 // Support selecting template as a function of the data being rendered
                 var templateName = typeof(template) == 'function' ? template(arrayValue) : template;
-                return executeTemplate(null, "ignoreTargetNode", templateName, createInnerBindingContext(arrayValue), options);
+                return executeTemplate(null, "ignoreTargetNode", templateName, createInnerBindingContext(arrayValue, index), options);
             }, options, activateBindingsCallback);
             
         }, null, { 'disposeWhenNodeIsRemoved': targetNode });
@@ -223,4 +225,4 @@
 })();
 
 ko.exportSymbol('ko.setTemplateEngine', ko.setTemplateEngine);
-ko.exportSymbol('ko.renderTemplate', ko.renderTemplate);
\ No newline at end of file
+ko.exportSymbol('ko.renderTemplate', ko.renderTemplate);