What is the formula for finding the total of rows when using ng-repeat?

Question

What is the formula for finding the total of rows when using ng-repeat?

I have a unique requirement that I would like you to consider before labeling as a duplicate. Let's delve into the following example:

<table ng:init="stuff={items:[{description:'gadget', cost:99,date:'jan3'},{description:'thing', cost:101,date:'july6'},{description:'thing', cost:101,date:'jan3'} ]}">
    <tr>
        <th>Description</th>
        <th>Cost</th>
    </tr>

    <tr ng:repeat="item in stuff.items|filter">   /*only display filtered items grouped by date*/    
        <td>{{item.description}}</td>
        <td ng-bind='item.cost'>{{item.cost}}</td>
    </tr>

    <tr>
        <td></td>
        <td>{{total}}</td>   /*total cost of items grouped by date jan3*/
    </tr>
</table>

How can I calculate the total cost of grouped items? Is there a data attribute in Angular where I can store and sum up the costs for each grouped item, before moving on to the next group?

javascript angularjs angularjs-ng-repeat angularjs-filter

Answer 1

Answer №1

Angular version 1.3 introduced a feature that allows you to create an alias for your ng-repeat, particularly beneficial when combined with a filter.

variable in expression as alias_expression
– In addition to the main expression, you can specify an optional alias expression to hold the results of the repeater after applying filters. This is commonly used to display a special message if a filter is active on the repeater but produces an empty result set.

For instance:
item in items | filter:x as results
assigns the filtered items fragment to results, but only after filtering.

Therefore, you can leverage as alias_expression for performing calculations on the filtered subset of your list. For example:

<tr ng-repeat="item in stuff.items|filter as filteredStuff">
  {{filteredStuff.length}}
  {{calculateTotal(filteredStuff)}}
</tr>

In the controller:

$scope.calculateTotal = function(filteredArray){
    var total = 0;
    angular.forEach(filteredArray, function(item){
        total += item.cost;
    });
    return total;
};

Answer 2

Angular version 1.3 introduced a feature that allows you to create an alias for your ng-repeat, particularly beneficial when combined with a filter.

variable in expression as alias_expression
– In addition to the main expression, you can specify an optional alias expression to hold the results of the repeater after applying filters. This is commonly used to display a special message if a filter is active on the repeater but produces an empty result set.

For instance:
item in items | filter:x as results
assigns the filtered items fragment to results, but only after filtering.

Therefore, you can leverage as alias_expression for performing calculations on the filtered subset of your list. For example:

<tr ng-repeat="item in stuff.items|filter as filteredStuff">
  {{filteredStuff.length}}
  {{calculateTotal(filteredStuff)}}
</tr>

In the controller:

$scope.calculateTotal = function(filteredArray){
    var total = 0;
    angular.forEach(filteredArray, function(item){
        total += item.cost;
    });
    return total;
};

Answer 3

Answer №2

If you want to calculate the total cost of all items in an array, you can create a custom filter for that purpose.

Custom Filter Markup

<tr ng:repeat="item in filteredData = (stuff.items|filter)">
    <td>{{item.description}}</td>
    <td ng-bind='item.cost'>{{item.cost}}</td>
</tr>
<tr>
    <td></td>
    <td>{{filteredData| total}}</td>   /*Total cost of grouped items*/
</tr>

Custom Filter Code

app.filter('total', function(){
  return function(array){
    var total = 0;
    angular.forEach(array, function(value, index){
       if(!isNaN(value.cost))
        total = total + parseFloat(value.cost);
    })
    return total;
  }
})

Answer 4

If you want to calculate the total cost of all items in an array, you can create a custom filter for that purpose.

Custom Filter Markup

<tr ng:repeat="item in filteredData = (stuff.items|filter)">
    <td>{{item.description}}</td>
    <td ng-bind='item.cost'>{{item.cost}}</td>
</tr>
<tr>
    <td></td>
    <td>{{filteredData| total}}</td>   /*Total cost of grouped items*/
</tr>

Custom Filter Code

app.filter('total', function(){
  return function(array){
    var total = 0;
    angular.forEach(array, function(value, index){
       if(!isNaN(value.cost))
        total = total + parseFloat(value.cost);
    })
    return total;
  }
})

What is the formula for finding the total of rows when using ng-repeat?

Answer №1

Answer №2

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