AngularJS is a popular JavaScript framework that helps developers build dynamic web applications. One of the components often used in AngularJS applications is the UI Grid, which allows for displaying and editing tabular data. In this article, we'll explore how to dynamically change the font color of a cell in an AngularJS UI Grid while it is being edited.
1. Background
To change the font color dynamically in an AngularJS UI Grid, we can leverage the ng-class directive and the $watch function. Below is a basic example that showcases how we can achieve this effect while editing a textarea.
Code Example for Textarea
<!DOCTYPE html>
<html ng-app="app">
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.9/angular.min.js"></script>
</head>
<body>
<div ng-controller="ctrl">
<textarea ng-model="val" ng-class="{'red': invalidTextArea}"></textarea>
</div>
<style>
.red {
color: red;
}
</style>
<script>
angular.module('app', []).controller('ctrl', function ($scope) {
$scope.$watch('val', function () {
$scope.invalidTextArea = ($scope.val === 'foo');
});
});
</script>
</body>
</html>
In the example above, the text color of the textarea changes to red when the user types "foo". This illustrates how we can use AngularJS to watch for changes in a model and apply conditional CSS classes.
2. Observations
To extend this functionality to an AngularJS UI Grid, we can utilize the cellClass and ng-class directives.
2.1 Changing Font Color After Cell Edit
Using the cellClass property, you can conditionally change the cell's font color when editing is finished (i.e., the cell loses focus).
Code Example
<!DOCTYPE html>
<html ng-app="app">
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.9/angular.min.js"></script>
<script src="https://cdn.rawgit.com/angular-ui/ui-grid.info/gh-pages/release/4.4.5/ui-grid.min.js"></script>
<link rel="stylesheet" href="https://cdn.rawgit.com/angular-ui/ui-grid.info/gh-pages/release/4.4.5/ui-grid.min.css"/>
</head>
<body>
<div ng-controller="ctrl">
<div ui-grid="gridOptions" ui-grid-edit></div>
</div>
<style>
.red {
color: red;
}
</style>
<script>
angular.module('app', ['ui.grid', 'ui.grid.edit']).controller('ctrl', function ($scope) {
$scope.gridOptions = {
data: [{ name: "" }],
columnDefs: [
{
field: 'Name',
cellClass: function (grid, row, col) {
if (grid.getCellValue(row, col) === 'foo') {
return 'red';
}
}
}
]
};
});
</script>
</body>
</html>
2.2 Changing Font Color During Cell Edit
To change the font color of the cell while it is being edited, we can utilize ng-class directly in the grid definition alongside the afterCellEdit event.
Code Example
<!DOCTYPE html>
<html ng-app="app">
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.9/angular.min.js"></script>
<script src="https://cdn.rawgit.com/angular-ui/ui-grid.info/gh-pages/release/4.4.5/ui-grid.min.js"></script>
<link rel="stylesheet" href="https://cdn.rawgit.com/angular-ui/ui-grid.info/gh-pages/release/4.4.5/ui-grid.min.css"/>
</head>
<body>
<div ng-controller="ctrl">
<div ui-grid="gridOptions" ui-grid-edit ng-class="{'red': invalidCell}"></div>
</div>
<style>
.red {
color: red;
}
</style>
<script>
angular.module('app', ['ui.grid', 'ui.grid.edit']).controller('ctrl', function ($scope) {
$scope.gridOptions = {
data: [{ name: "" }],
};
$scope.gridOptions.onRegisterApi = function (gridApi) {
$scope.gridApi = gridApi;
$scope.gridApi.edit.on.afterCellEdit($scope, function(rowEntity, colDef, newValue){
$scope.invalidCell = (newValue === 'foo');
});
};
});
</script>
</body>
</html>
3. Question
How can the above code snippets be modified so that the font color of the cell changes from black to red while it is being edited (i.e., not after edition is complete / cell focus is lost)?
Answer
To change the cell font color dynamically while editing, instead of using the afterCellEdit event, you'll need to apply a class dynamically within the cell editor itself. A modified approach would involve listening for keypress events or using the cellTemplate to bind the class directly during the editing phase.
Example of Dynamic Class During Editing
This example assumes that you're using a custom cell template that allows applying classes conditionally as the user types:
{
field: 'Name',
cellTemplate: '<input type="text" ng-model="row.entity[col.field]" ng-class="{\'red\': row.entity[col.field] === \'foo\'}" />'
}
By defining the ng-class directly in the input field of the cell template, the color changes immediately as the user types, allowing a seamless editing experience.
Conclusion
In this article, we discussed how to change the font color of an AngularJS UI Grid cell dynamically during cell editing. By leveraging AngularJS features such as $watch, cellClass, and ng-class, we can create responsive user interfaces that reflect user input in real-time.
Additional Note
When using these techniques, always ensure to test your application for performance, especially with larger datasets or complex UIs, to maintain a smooth user experience.
If you have more questions or need further clarification, feel free to reach out or leave a comment!
