st-table convert string to date - angularjs

Question

I have json object array binded to a table. Objects have a date column which is in date format but string. I need to change date format.
I tried;
<tbody>
<tr ng-repeat="row in table_data">
<td>{{row.availabledate | date:'MMMM dd, yyyy'}}</td>
</tr>
</tbody>
But, since it is string it is not formatted. I dont want to convert it in a loop for the sake of performance. Is there a way to convert this string to date and then format it on html part?

Answer 1

One way is to make your own filter, then use the date filter.
This crude/raw filter expects a YYYYMMDD string and creates a date object from it that you can then use angular's date filter on.
app.filter('strToDate', function() {
return function(input) {
var year = input.substring(0,4);
var month = input.substring(4,6);
var day = input.substring(6,8);
// Do filter work here
return new Date(year,month,day);
}
});
and then
<td>{{row.availabledate | strToDate | date:'MMMM dd, yyyy'}}</td>
Here's a Plunker link with working example: https://plnkr.co/edit/hn5StpktiMLq2gWHAszu?p=preview
You could also just make your filter return the formatted date.

Answer 2

Another way, doing all the work inside the filter:
app.filter('strToDate', function($filter) {
//1. date value
//2. the format input by user
return function(input, format) {
//Create the date object
var year = input.substring(0,4);
var month = input.substring(4,6);
var day = input.substring(6,8);
var newDate = new Date(year,month,day);
// return the format selected
return $filter('date')(newDate , format)
}
});
You can use the filter like this:
<td>{{row.availabledate | strToDate :'MMMM dd, yyyy'}}</td>