ArticleZip > Angularjs Template Default Value If Binding Null Undefined With Filter

Angularjs Template Default Value If Binding Null Undefined With Filter

AngularJS is an incredibly powerful framework for building dynamic web applications, and one of its most fundamental features is the use of templates to bind data to your UI. When working with AngularJS templates, you may encounter situations where you need to provide a default value when a binding is null or undefined. This can be particularly useful when you want to display placeholder text or a default value in your UI when the bound data is missing.

In AngularJS, you can achieve this by using filters in your templates. Filters are a powerful way to transform data before it is displayed in the UI, and they can be used to provide default values for null or undefined bindings. Let's walk through how you can accomplish this in your AngularJS code.

First, let's consider a simple example where we have a variable called `myValue` that may be null or undefined. We want to display a default message 'No data available' when `myValue` is null or undefined in our template.

We can achieve this by using the AngularJS `||` operator in conjunction with a filter. Here's how you can do it:

Html

<div>
  <p>{{ myValue || 'No data available' }}</p>
</div>

In this snippet, we are using the `||` operator to provide the default value 'No data available' if `myValue` is null or undefined. The `||` operator checks if the left operand is truthy, and if it is, it returns the left operand; otherwise, it returns the right operand.

Now, let's take a look at how you can create a custom filter in AngularJS to achieve the same result. Custom filters are a great way to encapsulate transformation logic and reuse it across your application.

First, define a custom filter in your AngularJS module:

Js

angular.module('myApp', [])
  .filter('defaultValue', function() {
    return function(input, defaultValue) {
      return input || defaultValue;
    };
  });

Next, you can use this custom filter in your template:

Html

<div>
  <p>{{ myValue | defaultValue:'No data available' }}</p>
</div>

In this example, we have defined a custom filter called `defaultValue` that takes two arguments: the input value and the default value. The filter returns the input value if it is truthy; otherwise, it returns the default value.

By utilizing filters in AngularJS, you can easily provide default values for null or undefined bindings in your templates, making your UI more robust and user-friendly. Whether you choose to use the `||` operator directly in your templates or create custom filters for more complex scenarios, AngularJS offers a flexible and powerful way to handle data binding defaults.

Related posts:

×