Get last index of an array using Angular ng-repeat

Question

I have an Object that I'm iterating over, that contains array values, here's an example (Note that my version has a lot more information than just content):

$scope.messages = { "1": [ 
    { "content": "Hello" },
    { "content": "How are you" },
    { "content": "This should be displayed" }
]};

Take this as a "messaging thread" type of scenario, where you would group the threads by a phone number (in this event, 1) and then show the last received message (the last index of the array).

Here's what I've tried, but it doesn't work.

<div ng-repeat="(thread_id, message_data) in messages">
    Thread ID: {{thread_id}} <br>
    Last message: {{message_data[message_data.length - 1].content}}
</div>

The thread id shows, but the message data does not.

Hardcoding the value such as:

{{message_data[0].content}}

works as expected.

Before people start suggesting $last please note that $last only returns true or false, depending on if the ng-repeat iteration is on its last cycle. Considering I'm using a (key, value) pair, and in my case the array is the value. I need the array length of the value, which value.length does provide. In this event:

 {{ message_data.length }}

will print out the value of 3. However using message_data.length - 1 to obtain a value from the array does not work.

@Trushnar - The $last variable returns a boolean, it says so straight on the document page. I need to get the length of the array in the (key, value) structure. Where the array is the value.. $last only returns true or false if the current ng-repeat iteration is on the last index. (In this case, it's the index of threads, not the index of messages) — Hobbyist
– Hobbyist, Commented Oct 9, 2015 at 7:10
works perfectly here jsfiddle.net/0jatojvg you have some internal issue, or given information is not enough to see the issue — guramidev
– guramidev, Commented Oct 9, 2015 at 7:18
@GuramiDagundaridze - Oh joyous, aren't those the best! I just got it to work due to a suggestion by a friend. Which was to change the code to message_data[(message_data.length - 1)].content and apparently the parenthesis solved the issue. — Hobbyist
– Hobbyist, Commented Oct 9, 2015 at 7:19
i am still curious because in fiddle it works without parenthesis. Must be a version difference thing — guramidev
– guramidev, Commented Oct 9, 2015 at 7:20

Barak · Accepted Answer · 2016-08-05 02:21:52Z

1

Add this to your html

ng-init="$last ? getLastIndex($index) : ''"

Js

$scope.getLastIndex = function (index){
  $scope.lastIndex = index;
}

Then this should work fine

message_data[lastIndex].content

answered Aug 5, 2016 at 2:21

Barak

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Hobbyist · Accepted Answer · 2015-10-09 07:20:36Z

0

While my exact scenario may not be present on all versions of AngularJS, I solved the issue by surrounding my math in parenthesis.

message_data[(message_data.length - 1)].content

answered Oct 9, 2015 at 7:20

Hobbyist

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