Generate a dynamic chart using Angular-chart.js on a canvas that is created on the fly

Question

Generate a dynamic chart using Angular-chart.js on a canvas that is created on the fly

I am facing an issue with displaying a chart or table in a div based on an XHR response. In the case of a chart, I want to replace the div contents with a canvas element that will be used by chart.js to show a graph.

When I directly include the canvas element in the HTML code, angular-chart.js successfully renders the graph. However, if I dynamically inject the canvas into the div using JavaScript, although the canvas element is present in the DOM, the chart does not display.

How can I resolve this problem?

HTML

<div ng-controller="ChartCtrl">
  <div>
    {{chart.name}}
    This works (doughnut):
    <canvas id="chart-{{$index}}" class="chart chart-doughnut" chart-data="chart.data" chart-labels="chart.labels"></canvas>
  </div>
  This Doesn't work ({{chart.type}}):
  <div id="chartDiv"> </div>
</div>

Javascript

var myApp = angular.module('myApp', ['chart.js']);

// Create the controller, the 'ToddlerCtrl' parameter 
// must match an ng-controller directive
myApp.controller('ChartCtrl', function ($scope) {
   var chart_div = $('#chartDiv');
   chart_div.empty();
   canvas_html = '<canvas id="chart-2" class="chart chart-doughnut" chart-data="chart.data" chart-labels="chart.labels"></canvas>';
   console.log(canvas_html)
   chart_div.append(canvas_html);
   //console.log(chart_div)
  $scope.chart =    {
     name: 'Chart 1',
     type: 'Doughnut',
     labels: ['EVSC', 'ISB'],
     data: [13, 44]
   };
});

Plunker Example: http://plnkr.co/edit/9JkANojIl8EXRj3hJNVH?p=preview

javascript angularjs chart.js angular-chartist.js

Answer 1

Answer №1

To modify the structure of the DOM, you cannot simply append your newly created element using traditional "vanilla" or "jQuery" methods.

Instead, you must compile your HTML string or DOM element to generate a template function that will be associated with the scope. This process involves traversing the DOM tree and matching DOM elements with relevant directives.

// Initialize the application, ensuring 'myApp' matches ng-app
var myApp = angular.module('myApp', ['chart.js']);

// Define the controller, naming it 'ChartCtrl' as per the ng-controller directive
myApp.controller('ChartCtrl', function ($scope, $compile) {
  canvas_html = '<canvas id="chart-2" class="chart chart-doughnut" chart-data="chart.data" chart-labels="chart.labels"></canvas>';

  var element = angular.element(canvas_html);
  $compile(element)($scope);
  angular.element('#chartDiv').append(element);

  $scope.chart =    {
     name: 'Chart 1',
     type: 'Doughnut',
     labels: ['EVSC', 'ISB'],
     data: [13, 44]
   };
});

You can view the outcome in this Plunker demo.

Answer 2

To modify the structure of the DOM, you cannot simply append your newly created element using traditional "vanilla" or "jQuery" methods.

Instead, you must compile your HTML string or DOM element to generate a template function that will be associated with the scope. This process involves traversing the DOM tree and matching DOM elements with relevant directives.

// Initialize the application, ensuring 'myApp' matches ng-app
var myApp = angular.module('myApp', ['chart.js']);

// Define the controller, naming it 'ChartCtrl' as per the ng-controller directive
myApp.controller('ChartCtrl', function ($scope, $compile) {
  canvas_html = '<canvas id="chart-2" class="chart chart-doughnut" chart-data="chart.data" chart-labels="chart.labels"></canvas>';

  var element = angular.element(canvas_html);
  $compile(element)($scope);
  angular.element('#chartDiv').append(element);

  $scope.chart =    {
     name: 'Chart 1',
     type: 'Doughnut',
     labels: ['EVSC', 'ISB'],
     data: [13, 44]
   };
});

You can view the outcome in this Plunker demo.

Answer 3

Answer №2

Wow, @HiDeo really nailed it with their answer! I have a more simplified Directive that achieves the same outcome. One key thing to note is the use of $compile. The chartData variable linked to the scope contains presets for Chartjs' charts, which can be customized as needed. An important addition is the $watch function on the update property to ensure smooth chart updates.

.directive('replaceWithChart',function($compile){
    return {
        restrict: 'A',
        scope: {
            chartData: '=replaceWithChart',
            height: '=',
            width: '='
        },
        compile: function(element){
            var canvasModel = angular.element('<canvas></canvas>');
            return {
                post: function postLink(scope,elem,attr){
                    elem.empty();
                    var canvas = canvasModel.clone();
                    elem.append($compile(canvas)(scope));

                    !scope.height && (scope.height = elem[0].style.height || (elem[0].offsetHeight || elem[0].clientHeight));
                    !scope.width && (scope.width = elem[0].style.width || (elem[0].offsetWidth || elem[0].clientWidth));

                    var chart = new Chart(canvas[0].getContext('2d'),scope.chartData);
                    canvas.attr('height',(canvas[0].style.height = scope.height + 'px'));
                    canvas.attr('width',(canvas[0].style.width = scope.width + 'px'));

                    scope.$watch('chartData.update',function(){
                        scope.chartData.update && !(scope.chartData.update = false) && chart.update();
                    });
                    elem.on('$destroy',chart.destroy.bind(chart));
                    // Fixed some rendering issue, but I can't remember which
                    window.setTimeout(function(){
                        var padding = elem[0].style.padding || (window.getComputedStyle(elem[0],null).getPropertyValue('padding'));
                        elem[0].style.padding = '0';
                        elem[0].style.padding = padding;
                        chart.resize();
                    },300); // Magic number - I found this worked best
                }
            };
        }
    };
})

Answer 4

Wow, @HiDeo really nailed it with their answer! I have a more simplified Directive that achieves the same outcome. One key thing to note is the use of $compile. The chartData variable linked to the scope contains presets for Chartjs' charts, which can be customized as needed. An important addition is the $watch function on the update property to ensure smooth chart updates.

.directive('replaceWithChart',function($compile){
    return {
        restrict: 'A',
        scope: {
            chartData: '=replaceWithChart',
            height: '=',
            width: '='
        },
        compile: function(element){
            var canvasModel = angular.element('<canvas></canvas>');
            return {
                post: function postLink(scope,elem,attr){
                    elem.empty();
                    var canvas = canvasModel.clone();
                    elem.append($compile(canvas)(scope));

                    !scope.height && (scope.height = elem[0].style.height || (elem[0].offsetHeight || elem[0].clientHeight));
                    !scope.width && (scope.width = elem[0].style.width || (elem[0].offsetWidth || elem[0].clientWidth));

                    var chart = new Chart(canvas[0].getContext('2d'),scope.chartData);
                    canvas.attr('height',(canvas[0].style.height = scope.height + 'px'));
                    canvas.attr('width',(canvas[0].style.width = scope.width + 'px'));

                    scope.$watch('chartData.update',function(){
                        scope.chartData.update && !(scope.chartData.update = false) && chart.update();
                    });
                    elem.on('$destroy',chart.destroy.bind(chart));
                    // Fixed some rendering issue, but I can't remember which
                    window.setTimeout(function(){
                        var padding = elem[0].style.padding || (window.getComputedStyle(elem[0],null).getPropertyValue('padding'));
                        elem[0].style.padding = '0';
                        elem[0].style.padding = padding;
                        chart.resize();
                    },300); // Magic number - I found this worked best
                }
            };
        }
    };
})

Generate a dynamic chart using Angular-chart.js on a canvas that is created on the fly

Answer №1

Answer №2

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