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fix(ngRepeat): expose $first, $middle and $last instead of $position

$position marker doesn't work well in cases when we have just one item
in the list because then the item is both the first and last. To solve
this properly we need to expose individual $first and $middle and $last
flags.

BREAKING CHANGE: $position is not exposed in repeater scopes any more

To update, search for $position and replace it with one of $first,
$middle or $last.

Closes #912
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1 parent 84542d2 commit 1d388676e3b97b6171fc498e82545bd437ee6fd1 @maxmart maxmart committed with IgorMinar May 2, 2012
Showing with 34 additions and 18 deletions.
  1. +7 −7 src/ng/directive/ngRepeat.js
  2. +27 −11 test/ng/directive/ngRepeatSpec.js
@@ -12,10 +12,9 @@
* Special properties are exposed on the local scope of each template instance, including:
*
* * `$index` – `{number}` – iterator offset of the repeated element (0..length-1)
- * * `$position` – `{string}` – position of the repeated element in the iterator. One of:
- * * `'first'`,
- * * `'middle'`
- * * `'last'`
+ * * `$first` – `{boolean}` – true if the repeated element is first in the iterator.
+ * * `$middle` – `{boolean}` – true if the repeated element is between the first and last in the iterator.
+ * * `$last` – `{boolean}` – true if the repeated element is last in the iterator.
*
*
* @element ANY
@@ -145,9 +144,10 @@ var ngRepeatDirective = ngDirective({
childScope[valueIdent] = value;
if (keyIdent) childScope[keyIdent] = key;
childScope.$index = index;
- childScope.$position = index === 0 ?
- 'first' :
- (index == collectionLength - 1 ? 'last' : 'middle');
+
+ childScope.$first = (index === 0);
+ childScope.$last = (index === (collectionLength - 1));
+ childScope.$middle = !(childScope.$first || childScope.$last);
if (!last) {
linker(childScope, function(clone){
@@ -104,42 +104,58 @@ describe('ngRepeat', function() {
}));
- it('should expose iterator position as $position when iterating over arrays',
+ it('should expose iterator position as $first, $middle and $last when iterating over arrays',
inject(function($rootScope, $compile) {
element = $compile(
'<ul>' +
- '<li ng-repeat="item in items" ng-bind="item + \':\' + $position + \'|\'"></li>' +
+ '<li ng-repeat="item in items">{{item}}:{{$first}}-{{$middle}}-{{$last}}|</li>' +
'</ul>')($rootScope);
$rootScope.items = ['misko', 'shyam', 'doug'];
$rootScope.$digest();
- expect(element.text()).toEqual('misko:first|shyam:middle|doug:last|');
+ expect(element.text()).
+ toEqual('misko:true-false-false|shyam:false-true-false|doug:false-false-true|');
$rootScope.items.push('frodo');
$rootScope.$digest();
- expect(element.text()).toEqual('misko:first|shyam:middle|doug:middle|frodo:last|');
+ expect(element.text()).
+ toEqual('misko:true-false-false|' +
+ 'shyam:false-true-false|' +
+ 'doug:false-true-false|' +
+ 'frodo:false-false-true|');
$rootScope.items.pop();
$rootScope.items.pop();
$rootScope.$digest();
- expect(element.text()).toEqual('misko:first|shyam:last|');
+ expect(element.text()).toEqual('misko:true-false-false|shyam:false-false-true|');
+
+ $rootScope.items.pop();
+ $rootScope.$digest();
+ expect(element.text()).toEqual('misko:true-false-true|');
}));
- it('should expose iterator position as $position when iterating over objects',
+ it('should expose iterator position as $first, $middle and $last when iterating over objects',
inject(function($rootScope, $compile) {
element = $compile(
'<ul>' +
- '<li ng-repeat="(key, val) in items" ng-bind="key + \':\' + val + \':\' + $position + \'|\'">' +
- '</li>' +
+ '<li ng-repeat="(key, val) in items">{{key}}:{{val}}:{{$first}}-{{$middle}}-{{$last}}|</li>' +
'</ul>')($rootScope);
$rootScope.items = {'misko':'m', 'shyam':'s', 'doug':'d', 'frodo':'f'};
$rootScope.$digest();
- expect(element.text()).toEqual('doug:d:first|frodo:f:middle|misko:m:middle|shyam:s:last|');
+ expect(element.text()).
+ toEqual('doug:d:true-false-false|' +
+ 'frodo:f:false-true-false|' +
+ 'misko:m:false-true-false|' +
+ 'shyam:s:false-false-true|');
delete $rootScope.items.doug;
delete $rootScope.items.frodo;
$rootScope.$digest();
- expect(element.text()).toEqual('misko:m:first|shyam:s:last|');
+ expect(element.text()).toEqual('misko:m:true-false-false|shyam:s:false-false-true|');
+
+ delete $rootScope.items.shyam;
+ $rootScope.$digest();
+ expect(element.text()).toEqual('misko:m:true-false-true|');
}));
@@ -207,7 +223,7 @@ describe('ngRepeat', function() {
beforeEach(inject(function($rootScope, $compile) {
element = $compile(
'<ul>' +
- '<li ng-repeat="item in items" ng-bind="key + \':\' + val + \':\' + $position + \'|\'"></li>' +
+ '<li ng-repeat="item in items">{{key}}:{{val}}|></li>' +
'</ul>')($rootScope);
a = {};
b = {};

2 comments on commit 1d38867

@coli
coli commented on 1d38867 May 23, 2012

would it make sense to namespace all 4 of the variables? like $repeatParam={
index:"",
first:true,
middle:true,
last:true
}

@maxmart
Contributor

Well, that might be a bit too verbose. Compare
<li ng-class="{first: $repeatParam.first, last: $repeatParam.last}"></li>
to
<li ng-class="{first: $first, last: $last}"></li>

Although the namespace could be shorter, like $ng.first or $repeat.first, I think that just having the dollar sign prefix in front of first/middle/last/index is enough to not accidentally cause a conflict with any of the user's own variables.

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